Merge pull request 'refactor(hashing): introduce Hashable derive macro and migrate server types' (#82 ) from hashing-proc-macro into main

Reviewed-on: #82 Reviewed-by: Stas <business@jexter.tech>
refactor(hashing): introduce Hashable derive macro and migrate server types
2026-04-08 00:18:40 +00:00 · 2026-04-08 01:32:59 +02:00 · 2026-04-07 19:26:54 +00:00 · 2026-04-07 16:28:47 +02:00 · 2026-04-07 16:24:51 +02:00 · 2026-04-07 15:02:32 +02:00
67 changed files with 2839 additions and 1109 deletions
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -11,6 +11,7 @@ Arbiter distinguishes two kinds of peers:

 - **User Agent** — A client application used by the owner to manage the vault (create wallets, approve SDK clients, configure policies).
 - **SDK Client** — A consumer of signing capabilities, typically an automation tool. In the future, this could include a browser-based wallet.
+- **Recovery Operator** — A dormant recovery participant with narrowly scoped authority used only for custody recovery and operator replacement.

 ---

@@ -42,7 +43,149 @@ There is no bootstrap mechanism for SDK clients. They must be explicitly approve

 ---

-## 3. Server Identity
+## 3. Multi-Operator Governance
+
+When more than one User Agent is registered, the vault is treated as having multiple operators. In that mode, sensitive actions are governed by voting rather than by a single operator decision.
+
+### 3.1 Voting Rules
+
+Voting is based on the total number of registered operators:
+
+- **1 operator:** no vote is needed; the single operator decides directly.
+- **2 operators:** full consensus is required; both operators must approve.
+- **3 or more operators:** quorum is `floor(N / 2) + 1`.
+
+For a decision to count, the operator's approval or rejection must be signed by that operator's associated key. Unsigned votes, or votes that fail signature verification, are ignored.
+
+Examples:
+
+- **3 operators:** 2 approvals required
+- **4 operators:** 3 approvals required
+
+### 3.2 Actions Requiring a Vote
+
+In multi-operator mode, a successful vote is required for:
+
+- approving new SDK clients
+- granting an SDK client visibility to a wallet
+- approving a one-off transaction
+- approving creation of a persistent grant
+- approving operator replacement
+- approving server updates
+- updating Shamir secret-sharing parameters
+
+### 3.3 Special Rule for Key Rotation
+
+Key rotation always requires full quorum, regardless of the normal voting threshold.
+
+This is stricter than ordinary governance actions because rotating the root key requires every operator to participate in coordinated share refresh/update steps. The root key itself is not redistributed directly, but each operator's share material must be changed consistently.
+
+### 3.4 Root Key Custody
+
+When the vault has multiple operators, the vault root key is protected using Shamir secret sharing.
+
+The vault root key is encrypted in a way that requires reconstruction from user-held shares rather than from a single shared password.
+
+For ordinary operators, the Shamir threshold matches the ordinary governance quorum. For example:
+
+- **2 operators:** `2-of-2`
+- **3 operators:** `2-of-3`
+- **4 operators:** `3-of-4`
+
+In practice, the Shamir share set also includes Recovery Operator shares. This means the effective Shamir parameters are computed over the combined share pool while keeping the same threshold. For example:
+
+- **3 ordinary operators + 2 recovery shares:** `2-of-5`
+
+This ensures that the normal custody threshold follows the ordinary operator quorum, while still allowing dormant recovery shares to exist for break-glass recovery flows.
+
+### 3.5 Recovery Operators
+
+Recovery Operators are a separate peer type from ordinary vault operators.
+
+Their role is intentionally narrow. They can only:
+
+- participate in unsealing the vault
+- vote for operator replacement
+
+Recovery Operators do not participate in routine governance such as approving SDK clients, granting wallet visibility, approving transactions, creating grants, approving server updates, or changing Shamir parameters.
+
+### 3.6 Sleeping and Waking Recovery Operators
+
+By default, Recovery Operators are **sleeping** and do not participate in any active flow.
+
+Any ordinary operator may request that Recovery Operators **wake up**.
+
+Any ordinary operator may also cancel a pending wake-up request.
+
+This creates a dispute window before recovery powers become active. The default wake-up delay is **14 days**.
+
+Recovery Operators are therefore part of the break-glass recovery path rather than the normal operating quorum.
+
+The high-level recovery flow is:
+
+```mermaid
+sequenceDiagram
+    autonumber
+    actor Op as Ordinary Operator
+    participant Server
+    actor Other as Other Operator
+    actor Rec as Recovery Operator
+
+    Op->>Server: Request recovery wake-up
+    Server-->>Op: Wake-up pending
+    Note over Server: Default dispute window: 14 days
+
+    alt Wake-up cancelled during dispute window
+        Other->>Server: Cancel wake-up
+        Server-->>Op: Recovery cancelled
+        Server-->>Rec: Stay sleeping
+    else No cancellation for 14 days
+        Server-->>Rec: Wake up
+        Rec->>Server: Join recovery flow
+        critical Recovery authority
+            Rec->>Server: Participate in unseal
+            Rec->>Server: Vote on operator replacement
+        end
+        Server-->>Op: Recovery mode active
+    end
+```
+
+### 3.7 Committee Formation
+
+There are two ways to form a multi-operator committee:
+
+- convert an existing single-operator vault by adding new operators
+- bootstrap an unbootstrapped vault directly into multi-operator mode
+
+In both cases, committee formation is a coordinated process. Arbiter does not allow multi-operator custody to emerge implicitly from unrelated registrations.
+
+### 3.8 Bootstrapping an Unbootstrapped Vault into Multi-Operator Mode
+
+When an unbootstrapped vault is initialized as a multi-operator vault, the setup proceeds as follows:
+
+1. An operator connects to the unbootstrapped vault using a User Agent and the bootstrap token.
+2. During bootstrap setup, that operator declares:
+   - the total number of ordinary operators
+   - the total number of Recovery Operators
+3. The vault enters **multi-bootstrap mode**.
+4. While in multi-bootstrap mode:
+   - every ordinary operator must connect with a User Agent using the bootstrap token
+   - every Recovery Operator must also connect using the bootstrap token
+   - each participant is registered individually
+   - each participant's share is created and protected with that participant's credentials
+5. The vault is considered fully bootstrapped only after all declared operator and recovery-share registrations have completed successfully.
+
+This means the operator and recovery set is fixed at bootstrap completion time, based on the counts declared when multi-bootstrap mode was entered.
+
+### 3.9 Special Bootstrap Constraint for Two-Operator Vaults
+
+If a vault is declared with exactly **2 ordinary operators**, Arbiter requires at least **1 Recovery Operator** to be configured during bootstrap.
+
+This prevents the worst-case custody failure in which a `2-of-2` operator set becomes permanently unrecoverable after loss of a single operator.
+
+---
+
+## 4. Server Identity

 The server proves its identity using TLS with a self-signed certificate. The TLS private key is generated on first run and is long-term; no rotation mechanism exists yet due to the complexity of multi-peer coordination.

@@ -55,9 +198,9 @@ Peers verify the server by its **public key fingerprint**:

 ---

-## 4. Key Management
+## 5. Key Management

-### 4.1 Key Hierarchy
+### 5.1 Key Hierarchy

 There are three layers of keys:

@@ -72,19 +215,19 @@ This layered design enables:
 - **Password rotation** without re-encrypting every wallet key (only the root key is re-encrypted).
 - **Root key rotation** without requiring the user to change their password.

-### 4.2 Encryption at Rest
+### 5.2 Encryption at Rest

 The database stores everything in encrypted form using symmetric AEAD. The encryption scheme is versioned to support transparent migration — when the vault unseals, Arbiter automatically re-encrypts any entries that are behind the current scheme version. See [IMPLEMENTATION.md](IMPLEMENTATION.md) for the specific scheme and versioning mechanism.

 ---

-## 5. Vault Lifecycle
+## 6. Vault Lifecycle

-### 5.1 Sealed State
+### 6.1 Sealed State

 On boot, the root key is encrypted and the server cannot perform any signing operations. This state is called **Sealed**.

-### 5.2 Unseal Flow
+### 6.2 Unseal Flow

 To transition to the **Unsealed** state, a User Agent must provide the password:

@@ -95,7 +238,7 @@ To transition to the **Unsealed** state, a User Agent must provide the password:
   - **Success:** The root key is decrypted and placed into a hardened memory cell. The server transitions to `Unsealed`. Any entries pending encryption scheme migration are re-encrypted.
   - **Failure:** The server returns an error indicating the password is incorrect.

-### 5.3 Memory Protection
+### 6.3 Memory Protection

 Once unsealed, the root key must be protected in memory against:

@@ -107,9 +250,9 @@ See [IMPLEMENTATION.md](IMPLEMENTATION.md) for the current and planned memory pr

 ---

-## 6. Permission Engine
+## 7. Permission Engine

-### 6.1 Fundamental Rules
+### 7.1 Fundamental Rules

 - SDK clients have **no access by default**.
 - Access is granted **explicitly** by a User Agent.
@@ -119,11 +262,45 @@ Each blockchain requires its own policy system due to differences in static tran

 Arbiter is also responsible for ensuring that **transaction nonces are never reused**.

-### 6.2 EVM Policies
+### 7.2 EVM Policies

 Every EVM grant is scoped to a specific **wallet** and **chain ID**.

-#### 6.2.1 Transaction Sub-Grants
+#### 7.2.0 Transaction Signing Sequence
+
+The high-level interaction order is:
+
+```mermaid
+sequenceDiagram
+    autonumber
+    actor SDK as SDK Client
+    participant Server
+    participant UA as User Agent
+
+    SDK->>Server: SignTransactionRequest
+    Server->>Server: Resolve wallet and wallet visibility
+    alt Visibility approval required
+        Server->>UA: Ask for wallet visibility approval
+        UA-->>Server: Vote result
+    end
+    Server->>Server: Evaluate transaction
+    Server->>Server: Load grant and limits context
+    alt Grant approval required
+        Server->>UA: Ask for execution / grant approval
+        UA-->>Server: Vote result
+        opt Create persistent grant
+            Server->>Server: Create and store grant
+        end
+        Server->>Server: Retry evaluation
+    end
+    critical Final authorization path
+        Server->>Server: Check limits and record execution
+        Server-->>Server: Signature or evaluation error
+    end
+    Server-->>SDK: Signature or error
+```
+
+#### 7.2.1 Transaction Sub-Grants

 Arbiter maintains an ever-expanding database of known contracts and their ABIs. Based on contract knowledge, transaction requests fall into three categories:

@@ -147,7 +324,7 @@ Available restrictions:

 These transactions have no `calldata` and therefore cannot interact with contracts. They can be subject to the same volume and rate restrictions as above.

-#### 6.2.2 Global Limits
+#### 7.2.2 Global Limits

 In addition to sub-grant-specific restrictions, the following limits can be applied across all grant types:

--- a/IMPLEMENTATION.md
+++ b/IMPLEMENTATION.md
@@ -67,18 +67,14 @@ The `program_client.nonce` column stores the **next usable nonce** — i.e. it i
 ## Cryptography

 ### Authentication
- **Client protocol:** ed25519
+- **Client protocol:** ML-DSA

 ### User-Agent Authentication

 User-agent authentication supports multiple signature schemes because platform-provided "hardware-bound" keys do not expose a uniform algorithm across operating systems and hardware.

- **Supported schemes:** RSA, Ed25519, ECDSA (secp256k1)
- **Why:** the user agent authenticates with keys backed by platform facilities, and those facilities differ by platform
- **Apple Silicon Secure Enclave / Secure Element:** ECDSA-only in practice
- **Windows Hello / TPM 2.0:** currently RSA-backed in our integration
-
-This is why the user-agent auth protocol carries an explicit `KeyType`, while the SDK client protocol remains fixed to ed25519.
+- **Supported schemes:** ML-DSA
+- **Why:** Secure Enclave (MacOS) support them natively, on other platforms we could emulate while they roll-out

 ### Encryption at Rest
 - **Scheme:** Symmetric AEAD — currently **XChaCha20-Poly1305**
@@ -128,6 +124,52 @@ The central abstraction is the `Policy` trait. Each implementation handles one s
 4. **Evaluate** — `Policy::evaluate` checks the decoded meaning against the grant's policy-specific constraints and returns any violations.
 5. **Record** — If `RunKind::Execution` and there are no violations, the engine writes to `evm_transaction_log` and calls `Policy::record_transaction` for any policy-specific logging (e.g., token transfer volume).

+The detailed branch structure is shown below:
+
+```mermaid
+flowchart TD
+    A[SDK Client sends sign transaction request] --> B[Server resolves wallet]
+    B --> C{Wallet exists?}
+
+    C -- No --> Z1[Return wallet not found error]
+    C -- Yes --> D[Check SDK client wallet visibility]
+
+    D --> E{Wallet visible to SDK client?}
+    E -- No --> F[Start wallet visibility voting flow]
+    F --> G{Vote approved?}
+    G -- No --> Z2[Return wallet access denied error]
+    G -- Yes --> H[Persist wallet visibility]
+    E -- Yes --> I[Classify transaction meaning]
+    H --> I
+
+    I --> J{Meaning supported?}
+    J -- No --> Z3[Return unsupported transaction error]
+    J -- Yes --> K[Find matching grant]
+
+    K --> L{Grant exists?}
+    L -- Yes --> M[Check grant limits]
+    L -- No --> N[Start execution or grant voting flow]
+
+    N --> O{User-agent decision}
+    O -- Reject --> Z4[Return no matching grant error]
+    O -- Allow once --> M
+    O -- Create grant --> P[Create grant with user-selected limits]
+    P --> Q[Persist grant]
+    Q --> M
+
+    M --> R{Limits exceeded?}
+    R -- Yes --> Z5[Return evaluation error]
+    R -- No --> S[Record transaction in logs]
+    S --> T[Produce signature]
+    T --> U[Return signature to SDK client]
+
+    note1[Limit checks include volume, count, and gas constraints.]
+    note2[Grant lookup depends on classified meaning, such as ether transfer or token transfer.]
+
+    K -. uses .-> note2
+    M -. checks .-> note1
+```
+
 ### Policy Trait

 | Method | Purpose |
--- a/mise.lock
+++ b/mise.lock
@@ -48,6 +48,10 @@ backend = "cargo:cargo-features-manager"
 version = "1.46.3"
 backend = "cargo:cargo-insta"

+[[tools."cargo:cargo-mutants"]]
+version = "27.0.0"
+backend = "cargo:cargo-mutants"
+
 [[tools."cargo:cargo-nextest"]]
 version = "0.9.126"
 backend = "cargo:cargo-nextest"
@@ -111,30 +115,37 @@ backend = "core:python"
 [tools.python."platforms.linux-arm64"]
 checksum = "sha256:53700338695e402a1a1fe22be4a41fbdacc70e22bb308a48eca8ed67cb7992be"
 url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260324/cpython-3.14.3+20260324-aarch64-unknown-linux-gnu-install_only_stripped.tar.gz"
+provenance = "github-attestations"

 [tools.python."platforms.linux-arm64-musl"]
 checksum = "sha256:53700338695e402a1a1fe22be4a41fbdacc70e22bb308a48eca8ed67cb7992be"
 url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260324/cpython-3.14.3+20260324-aarch64-unknown-linux-gnu-install_only_stripped.tar.gz"
+provenance = "github-attestations"

 [tools.python."platforms.linux-x64"]
 checksum = "sha256:d7a9f970914bb4c88756fe3bdcc186d4feb90e9500e54f1db47dae4dc9687e39"
 url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260324/cpython-3.14.3+20260324-x86_64-unknown-linux-gnu-install_only_stripped.tar.gz"
+provenance = "github-attestations"

 [tools.python."platforms.linux-x64-musl"]
 checksum = "sha256:d7a9f970914bb4c88756fe3bdcc186d4feb90e9500e54f1db47dae4dc9687e39"
 url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260324/cpython-3.14.3+20260324-x86_64-unknown-linux-gnu-install_only_stripped.tar.gz"
+provenance = "github-attestations"

 [tools.python."platforms.macos-arm64"]
 checksum = "sha256:c43aecde4a663aebff99b9b83da0efec506479f1c3f98331442f33d2c43501f9"
 url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260324/cpython-3.14.3+20260324-aarch64-apple-darwin-install_only_stripped.tar.gz"
+provenance = "github-attestations"

 [tools.python."platforms.macos-x64"]
 checksum = "sha256:9ab41dbc2f100a2a45d1833b9c11165f51051c558b5213eda9a9731d5948a0c0"
 url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260324/cpython-3.14.3+20260324-x86_64-apple-darwin-install_only_stripped.tar.gz"
+provenance = "github-attestations"

 [tools.python."platforms.windows-x64"]
 checksum = "sha256:bbe19034b35b0267176a7442575ae7dc6343480fd4d35598cb7700173d431e09"
 url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260324/cpython-3.14.3+20260324-x86_64-pc-windows-msvc-install_only_stripped.tar.gz"
+provenance = "github-attestations"

 [[tools.rust]]
 version = "1.93.0"
--- a/mise.toml
+++ b/mise.toml
@@ -12,6 +12,7 @@ protoc = "29.6"
 python = "3.14.3"
 ast-grep = "0.42.0"
 "cargo:cargo-edit" = "0.13.9"
+"cargo:cargo-mutants" = "27.0.0"

 [tasks.codegen]
 sources = ['protobufs/*.proto', 'protobufs/**/*.proto']
--- a/protobufs/shared/evm.proto
+++ b/protobufs/shared/evm.proto
@@ -36,6 +36,10 @@ message GasLimitExceededViolation {
 }

 message EvalViolation {
+  message ChainIdMismatch {
+    uint64 expected = 1;
+    uint64 actual = 2;
+  }
  oneof kind {
    bytes invalid_target = 1; // 20-byte Ethereum address
    GasLimitExceededViolation gas_limit_exceeded = 2;
@@ -43,6 +47,8 @@ message EvalViolation {
    google.protobuf.Empty volumetric_limit_exceeded = 4;
    google.protobuf.Empty invalid_time = 5;
    google.protobuf.Empty invalid_transaction_type = 6;
+
+    ChainIdMismatch chain_id_mismatch = 7;
  }
 }

--- a/server/.cargo/mutants.toml
+++ b/server/.cargo/mutants.toml
@@ -0,0 +1 @@
+test_tool = "nextest"
--- a/server/.gitignore
+++ b/server/.gitignore
@@ -0,0 +1,2 @@
+mutants.out/
+mutants.out.old/
--- a/server/Cargo.lock
+++ b/server/Cargo.lock
@@ -347,7 +347,7 @@ dependencies = [
 "ruint",
 "rustc-hash",
 "serde",
- "sha3",
+ "sha3 0.10.8",
 ]

 [[package]]
@@ -548,7 +548,7 @@ dependencies = [
 "proc-macro-error2",
 "proc-macro2",
 "quote",
- "sha3",
+ "sha3 0.10.8",
 "syn 2.0.117",
 "syn-solidity",
 ]
@@ -680,9 +680,9 @@ name = "arbiter-client"
 version = "0.1.0"
 dependencies = [
 "alloy",
+ "arbiter-crypto",
 "arbiter-proto",
 "async-trait",
- "ed25519-dalek",
 "http",
 "rand 0.10.0",
 "rustls-webpki",
@@ -692,6 +692,29 @@ dependencies = [
 "tonic",
 ]

+[[package]]
+name = "arbiter-crypto"
+version = "0.1.0"
+dependencies = [
+ "alloy",
+ "base64",
+ "chrono",
+ "hmac",
+ "memsafe",
+ "ml-dsa",
+ "rand 0.10.0",
+]
+
+[[package]]
+name = "arbiter-macros"
+version = "0.1.0"
+dependencies = [
+ "arbiter-crypto",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.117",
+]
+
 [[package]]
 name = "arbiter-proto"
 version = "0.1.0"
@@ -725,6 +748,8 @@ version = "0.1.0"
 dependencies = [
 "alloy",
 "anyhow",
+ "arbiter-crypto",
+ "arbiter-macros",
 "arbiter-proto",
 "arbiter-tokens-registry",
 "argon2",
@@ -742,19 +767,24 @@ dependencies = [
 "insta",
 "k256",
 "kameo",
- "memsafe",
+ "ml-dsa",
+ "mutants",
 "pem",
+ "proptest",
+ "prost",
 "prost-types",
 "rand 0.10.0",
 "rcgen",
 "restructed",
- "rsa",
+ "rstest",
 "rustls",
 "secrecy",
+ "serde_with",
 "sha2 0.10.9",
 "smlang",
- "spki",
+ "spki 0.7.3",
 "strum 0.28.0",
+ "subtle",
 "test-log",
 "thiserror 2.0.18",
 "tokio",
@@ -1443,6 +1473,12 @@ dependencies = [
 "cc",
 ]

+[[package]]
+name = "cmov"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f88a43d011fc4a6876cb7344703e297c71dda42494fee094d5f7c76bf13f746"
+
 [[package]]
 name = "console"
 version = "0.15.11"
@@ -1473,6 +1509,12 @@ version = "0.9.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c2459377285ad874054d797f3ccebf984978aa39129f6eafde5cdc8315b612f8"

+[[package]]
+name = "const-oid"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a6ef517f0926dd24a1582492c791b6a4818a4d94e789a334894aa15b0d12f55c"
+
 [[package]]
 name = "const_format"
 version = "0.2.35"
@@ -1594,6 +1636,15 @@ dependencies = [
 "hybrid-array",
 ]

+[[package]]
+name = "ctutils"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d5515a3834141de9eafb9717ad39eea8247b5674e6066c404e8c4b365d2a29e"
+dependencies = [
+ "cmov",
+]
+
 [[package]]
 name = "curve25519-dalek"
 version = "4.1.3"
@@ -1732,8 +1783,17 @@ version = "0.7.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e7c1832837b905bbfb5101e07cc24c8deddf52f93225eee6ead5f4d63d53ddcb"
 dependencies = [
- "const-oid",
- "pem-rfc7468",
+ "const-oid 0.9.6",
+ "zeroize",
+]
+
+[[package]]
+name = "der"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "71fd89660b2dc699704064e59e9dba0147b903e85319429e131620d022be411b"
+dependencies = [
+ "const-oid 0.10.2",
 "zeroize",
 ]

@@ -1876,7 +1936,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
 dependencies = [
 "block-buffer 0.10.4",
- "const-oid",
+ "const-oid 0.9.6",
 "crypto-common 0.1.7",
 "subtle",
 ]
@@ -1940,13 +2000,13 @@ version = "0.16.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ee27f32b5c5292967d2d4a9d7f1e0b0aed2c15daded5a60300e4abb9d8020bca"
 dependencies = [
- "der",
+ "der 0.7.10",
 "digest 0.10.7",
 "elliptic-curve",
 "rfc6979",
 "serdect",
 "signature 2.2.0",
- "spki",
+ "spki 0.7.3",
 ]

 [[package]]
@@ -2005,7 +2065,7 @@ dependencies = [
 "ff",
 "generic-array",
 "group",
- "pkcs8",
+ "pkcs8 0.10.2",
 "rand_core 0.6.4",
 "sec1",
 "serdect",
@@ -2052,7 +2112,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
 "libc",
- "windows-sys 0.52.0",
+ "windows-sys 0.61.2",
 ]

 [[package]]
@@ -2552,6 +2612,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8655f91cd07f2b9d0c24137bd650fe69617773435ee5ec83022377777ce65ef1"
 dependencies = [
 "typenum",
+ "zeroize",
 ]

 [[package]]
@@ -2949,6 +3010,16 @@ dependencies = [
 "cpufeatures 0.2.17",
 ]

+[[package]]
+name = "keccak"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9e24a010dd405bd7ed803e5253182815b41bf2e6a80cc3bfc066658e03a198aa"
+dependencies = [
+ "cfg-if",
+ "cpufeatures 0.3.0",
+]
+
 [[package]]
 name = "keccak-asm"
 version = "0.1.5"
@@ -2964,9 +3035,6 @@ name = "lazy_static"
 version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
-dependencies = [
- "spin",
-]

 [[package]]
 name = "leb128fmt"
@@ -3165,12 +3233,46 @@ dependencies = [
 "windows-sys 0.61.2",
 ]

+[[package]]
+name = "ml-dsa"
+version = "0.1.0-rc.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f5b2bb0ad6fa2b40396775bd56f51345171490fef993f46f91a876ecdbdaea55"
+dependencies = [
+ "const-oid 0.10.2",
+ "ctutils",
+ "hybrid-array",
+ "module-lattice",
+ "pkcs8 0.11.0-rc.11",
+ "rand_core 0.10.0",
+ "sha3 0.11.0",
+ "signature 3.0.0-rc.10",
+ "zeroize",
+]
+
+[[package]]
+name = "module-lattice"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "164eb3faeaecbd14b0b2a917c1b4d0c035097a9c559b0bed85c2cdd032bc8faa"
+dependencies = [
+ "hybrid-array",
+ "num-traits",
+ "zeroize",
+]
+
 [[package]]
 name = "multimap"
 version = "0.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1d87ecb2933e8aeadb3e3a02b828fed80a7528047e68b4f424523a0981a3a084"

+[[package]]
+name = "mutants"
+version = "0.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "add0ac067452ff1aca8c5002111bd6b1c895baee6e45fcbc44e0193aea17be56"
+
 [[package]]
 name = "nom"
 version = "7.1.3"
@@ -3187,7 +3289,7 @@ version = "0.50.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
 dependencies = [
- "windows-sys 0.59.0",
+ "windows-sys 0.61.2",
 ]

 [[package]]
@@ -3200,22 +3302,6 @@ dependencies = [
 "num-traits",
 ]

-[[package]]
-name = "num-bigint-dig"
-version = "0.8.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e661dda6640fad38e827a6d4a310ff4763082116fe217f279885c97f511bb0b7"
-dependencies = [
- "lazy_static",
- "libm",
- "num-integer",
- "num-iter",
- "num-traits",
- "rand 0.8.5",
- "smallvec",
- "zeroize",
-]
-
 [[package]]
 name = "num-conv"
 version = "0.2.0"
@@ -3231,17 +3317,6 @@ dependencies = [
 "num-traits",
 ]

-[[package]]
-name = "num-iter"
-version = "0.1.45"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1429034a0490724d0075ebb2bc9e875d6503c3cf69e235a8941aa757d83ef5bf"
-dependencies = [
- "autocfg",
- "num-integer",
- "num-traits",
-]
-
 [[package]]
 name = "num-traits"
 version = "0.2.19"
@@ -3411,15 +3486,6 @@ dependencies = [
 "serde_core",
 ]

-[[package]]
-name = "pem-rfc7468"
-version = "0.7.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "88b39c9bfcfc231068454382784bb460aae594343fb030d46e9f50a645418412"
-dependencies = [
- "base64ct",
-]
-
 [[package]]
 name = "percent-encoding"
 version = "2.3.2"
@@ -3479,25 +3545,24 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"

-[[package]]
-name = "pkcs1"
-version = "0.7.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c8ffb9f10fa047879315e6625af03c164b16962a5368d724ed16323b68ace47f"
-dependencies = [
- "der",
- "pkcs8",
- "spki",
-]
-
 [[package]]
 name = "pkcs8"
 version = "0.10.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f950b2377845cebe5cf8b5165cb3cc1a5e0fa5cfa3e1f7f55707d8fd82e0a7b7"
 dependencies = [
- "der",
- "spki",
+ "der 0.7.10",
+ "spki 0.7.3",
+]
+
+[[package]]
+name = "pkcs8"
+version = "0.11.0-rc.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "12922b6296c06eb741b02d7b5161e3aaa22864af38dfa025a1a3ba3f68c84577"
+dependencies = [
+ "der 0.8.0",
+ "spki 0.8.0",
 ]

 [[package]]
@@ -3634,9 +3699,9 @@ dependencies = [

 [[package]]
 name = "proptest"
-version = "1.10.0"
+version = "1.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "37566cb3fdacef14c0737f9546df7cfeadbfbc9fef10991038bf5015d0c80532"
+checksum = "4b45fcc2344c680f5025fe57779faef368840d0bd1f42f216291f0dc4ace4744"
 dependencies = [
 "bit-set",
 "bit-vec",
@@ -4137,27 +4202,6 @@ dependencies = [
 "rustc-hex",
 ]

-[[package]]
-name = "rsa"
-version = "0.9.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b8573f03f5883dcaebdfcf4725caa1ecb9c15b2ef50c43a07b816e06799bb12d"
-dependencies = [
- "const-oid",
- "digest 0.10.7",
- "num-bigint-dig",
- "num-integer",
- "num-traits",
- "pkcs1",
- "pkcs8",
- "rand_core 0.6.4",
- "sha2 0.10.9",
- "signature 2.2.0",
- "spki",
- "subtle",
- "zeroize",
-]
-
 [[package]]
 name = "rsqlite-vfs"
 version = "0.1.0"
@@ -4286,7 +4330,7 @@ dependencies = [
 "errno",
 "libc",
 "linux-raw-sys",
- "windows-sys 0.52.0",
+ "windows-sys 0.61.2",
 ]

 [[package]]
@@ -4397,9 +4441,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d3e97a565f76233a6003f9f5c54be1d9c5bdfa3eccfb189469f11ec4901c47dc"
 dependencies = [
 "base16ct",
- "der",
+ "der 0.7.10",
 "generic-array",
- "pkcs8",
+ "pkcs8 0.10.2",
 "serdect",
 "subtle",
 "zeroize",
@@ -4593,7 +4637,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "75872d278a8f37ef87fa0ddbda7802605cb18344497949862c0d4dcb291eba60"
 dependencies = [
 "digest 0.10.7",
- "keccak",
+ "keccak 0.1.6",
+]
+
+[[package]]
+name = "sha3"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "be176f1a57ce4e3d31c1a166222d9768de5954f811601fb7ca06fc8203905ce1"
+dependencies = [
+ "digest 0.11.2",
+ "keccak 0.2.0",
 ]

 [[package]]
@@ -4646,6 +4700,10 @@ name = "signature"
 version = "3.0.0-rc.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f1880df446116126965eeec169136b2e0251dba37c6223bcc819569550edea3"
+dependencies = [
+ "digest 0.11.2",
+ "rand_core 0.10.0",
+]

 [[package]]
 name = "simd-adler32"
@@ -4702,15 +4760,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3a766e1110788c36f4fa1c2b71b387a7815aa65f88ce0229841826633d93723e"
 dependencies = [
 "libc",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]

-[[package]]
-name = "spin"
-version = "0.9.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
-
 [[package]]
 name = "spki"
 version = "0.7.3"
@@ -4718,7 +4770,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d91ed6c858b01f942cd56b37a94b3e0a1798290327d1236e4d9cf4eaca44d29d"
 dependencies = [
 "base64ct",
- "der",
+ "der 0.7.10",
+]
+
+[[package]]
+name = "spki"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d9efca8738c78ee9484207732f728b1ef517bbb1833d6fc0879ca898a522f6f"
+dependencies = [
+ "base64ct",
+ "der 0.8.0",
 ]

 [[package]]
@@ -4896,7 +4958,7 @@ dependencies = [
 "getrandom 0.4.2",
 "once_cell",
 "rustix",
- "windows-sys 0.52.0",
+ "windows-sys 0.61.2",
 ]

 [[package]]
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -20,7 +20,7 @@ tokio = { version = "1.50.0", features = ["full"] }
 ed25519-dalek = { version = "3.0.0-pre.6", features = ["rand_core"] }
 chrono = { version = "0.4.44", features = ["serde"] }
 rand = "0.10.0"
-rustls = { version = "0.23.37", features = ["aws-lc-rs"] }
+rustls = { version = "0.23.37", features = ["aws-lc-rs", "logging", "prefer-post-quantum", "std"], default-features = false }
 smlang = "0.8.0"
 thiserror = "2.0.18"
 async-trait = "0.1.89"
@@ -42,4 +42,9 @@ k256 = { version = "0.13.4", features = ["ecdsa", "pkcs8"] }
 rsa = { version = "0.9", features = ["sha2"] }
 sha2 = "0.10"
 spki = "0.7"
+prost = "0.14.3"
 miette = { version = "7.6.0", features = ["fancy", "serde"] }
+mutants = "0.0.4"
+ml-dsa = { version = "0.1.0-rc.8", features = ["zeroize"] }
+base64 = "0.22.1"
+hmac = "0.12.1"
--- a/server/crates/arbiter-client/Cargo.toml
+++ b/server/crates/arbiter-client/Cargo.toml
@@ -13,12 +13,12 @@ evm = ["dep:alloy"]

 [dependencies]
 arbiter-proto.path = "../arbiter-proto"
+arbiter-crypto.path = "../arbiter-crypto"
 alloy = { workspace = true, optional = true }
 tonic.workspace = true
 tonic.features = ["tls-aws-lc"]
 tokio.workspace = true
 tokio-stream.workspace = true
-ed25519-dalek.workspace = true
 thiserror.workspace = true
 http = "1.4.0"
 rustls-webpki = { version = "0.103.10", features = ["aws-lc-rs"] }
--- a/server/crates/arbiter-client/src/auth.rs
+++ b/server/crates/arbiter-client/src/auth.rs
@@ -1,5 +1,6 @@
+use arbiter_crypto::authn::{CLIENT_CONTEXT, SigningKey, format_challenge};
 use arbiter_proto::{
-    ClientMetadata, format_challenge,
+    ClientMetadata,
    proto::{
        client::{
            ClientRequest,
@@ -14,7 +15,6 @@ use arbiter_proto::{
        shared::ClientInfo as ProtoClientInfo,
    },
 };
-use ed25519_dalek::Signer as _;

 use crate::{
    storage::StorageError,
@@ -54,14 +54,14 @@ fn map_auth_result(code: i32) -> AuthError {
 async fn send_auth_challenge_request(
    transport: &mut ClientTransport,
    metadata: ClientMetadata,
-    key: &ed25519_dalek::SigningKey,
+    key: &SigningKey,
 ) -> std::result::Result<(), AuthError> {
    transport
        .send(ClientRequest {
            request_id: next_request_id(),
            payload: Some(ClientRequestPayload::Auth(proto_auth::Request {
                payload: Some(AuthRequestPayload::ChallengeRequest(AuthChallengeRequest {
-                    pubkey: key.verifying_key().to_bytes().to_vec(),
+                    pubkey: key.public_key().to_bytes(),
                    client_info: Some(ProtoClientInfo {
                        name: metadata.name,
                        description: metadata.description,
@@ -95,11 +95,14 @@ async fn receive_auth_challenge(

 async fn send_auth_challenge_solution(
    transport: &mut ClientTransport,
-    key: &ed25519_dalek::SigningKey,
+    key: &SigningKey,
    challenge: AuthChallenge,
 ) -> std::result::Result<(), AuthError> {
    let challenge_payload = format_challenge(challenge.nonce, &challenge.pubkey);
-    let signature = key.sign(&challenge_payload).to_bytes().to_vec();
+    let signature = key
+        .sign_message(&challenge_payload, CLIENT_CONTEXT)
+        .map_err(|_| AuthError::UnexpectedAuthResponse)?
+        .to_bytes();

    transport
        .send(ClientRequest {
@@ -140,7 +143,7 @@ async fn receive_auth_confirmation(
 pub(crate) async fn authenticate(
    transport: &mut ClientTransport,
    metadata: ClientMetadata,
-    key: &ed25519_dalek::SigningKey,
+    key: &SigningKey,
 ) -> std::result::Result<(), AuthError> {
    send_auth_challenge_request(transport, metadata, key).await?;
    let challenge = receive_auth_challenge(transport).await?;
--- a/server/crates/arbiter-client/src/client.rs
+++ b/server/crates/arbiter-client/src/client.rs
@@ -1,3 +1,4 @@
+use arbiter_crypto::authn::SigningKey;
 use arbiter_proto::{
    ClientMetadata, proto::arbiter_service_client::ArbiterServiceClient, url::ArbiterUrl,
 };
@@ -60,7 +61,7 @@ impl ArbiterClient {
    pub async fn connect_with_key(
        url: ArbiterUrl,
        metadata: ClientMetadata,
-        key: ed25519_dalek::SigningKey,
+        key: SigningKey,
    ) -> Result<Self, Error> {
        let anchor = webpki::anchor_from_trusted_cert(&url.ca_cert)?.to_owned();
        let tls = ClientTlsConfig::new().trust_anchor(anchor);
--- a/server/crates/arbiter-client/src/storage.rs
+++ b/server/crates/arbiter-client/src/storage.rs
@@ -1,3 +1,4 @@
+use arbiter_crypto::authn::SigningKey;
 use arbiter_proto::home_path;
 use std::path::{Path, PathBuf};

@@ -11,7 +12,7 @@ pub enum StorageError {
 }

 pub trait SigningKeyStorage {
-    fn load_or_create(&self) -> std::result::Result<ed25519_dalek::SigningKey, StorageError>;
+    fn load_or_create(&self) -> std::result::Result<SigningKey, StorageError>;
 }

 #[derive(Debug, Clone)]
@@ -20,7 +21,7 @@ pub struct FileSigningKeyStorage {
 }

 impl FileSigningKeyStorage {
-    pub const DEFAULT_FILE_NAME: &str = "sdk_client_ed25519.key";
+    pub const DEFAULT_FILE_NAME: &str = "sdk_client_ml_dsa.key";

    pub fn new(path: impl Into<PathBuf>) -> Self {
        Self { path: path.into() }
@@ -30,7 +31,7 @@ impl FileSigningKeyStorage {
        Ok(Self::new(home_path()?.join(Self::DEFAULT_FILE_NAME)))
    }

-    fn read_key(path: &Path) -> std::result::Result<ed25519_dalek::SigningKey, StorageError> {
+    fn read_key(path: &Path) -> std::result::Result<SigningKey, StorageError> {
        let bytes = std::fs::read(path)?;
        let raw: [u8; 32] =
            bytes
@@ -39,12 +40,12 @@ impl FileSigningKeyStorage {
                    expected: 32,
                    actual: v.len(),
                })?;
-        Ok(ed25519_dalek::SigningKey::from_bytes(&raw))
+        Ok(SigningKey::from_seed(raw))
    }
 }

 impl SigningKeyStorage for FileSigningKeyStorage {
-    fn load_or_create(&self) -> std::result::Result<ed25519_dalek::SigningKey, StorageError> {
+    fn load_or_create(&self) -> std::result::Result<SigningKey, StorageError> {
        if let Some(parent) = self.path.parent() {
            std::fs::create_dir_all(parent)?;
        }
@@ -53,8 +54,8 @@ impl SigningKeyStorage for FileSigningKeyStorage {
            return Self::read_key(&self.path);
        }

-        let key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-        let raw_key = key.to_bytes();
+        let key = SigningKey::generate();
+        let raw_key = key.to_seed();

        // Use create_new to prevent accidental overwrite if another process creates the key first.
        match std::fs::OpenOptions::new()
@@ -103,7 +104,7 @@ mod tests {
            .load_or_create()
            .expect("second load_or_create should read same key");

-        assert_eq!(key_a.to_bytes(), key_b.to_bytes());
+        assert_eq!(key_a.to_seed(), key_b.to_seed());
        assert!(path.exists());

        std::fs::remove_file(path).expect("temp key file should be removable");
--- a/server/crates/arbiter-crypto/.gitignore
+++ b/server/crates/arbiter-crypto/.gitignore
@@ -0,0 +1 @@
+/target
--- a/server/crates/arbiter-crypto/Cargo.toml
+++ b/server/crates/arbiter-crypto/Cargo.toml
@@ -0,0 +1,21 @@
+[package]
+name = "arbiter-crypto"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+ml-dsa = {workspace = true, optional = true }
+rand = {workspace = true, optional = true}
+base64 = {workspace = true, optional = true }
+memsafe = {version = "0.4.0", optional = true}
+hmac.workspace = true
+alloy.workspace = true
+chrono.workspace = true
+
+[lints]
+workspace = true
+
+[features]
+default = ["authn", "safecell"]
+authn = ["dep:ml-dsa", "dep:rand", "dep:base64"]
+safecell = ["dep:memsafe"]
--- a/server/crates/arbiter-crypto/src/authn/mod.rs
+++ b/server/crates/arbiter-crypto/src/authn/mod.rs
@@ -0,0 +1,2 @@
+pub mod v1;
+pub use v1::*;
--- a/server/crates/arbiter-crypto/src/authn/v1.rs
+++ b/server/crates/arbiter-crypto/src/authn/v1.rs
@@ -0,0 +1,193 @@
+use base64::{Engine as _, prelude::BASE64_STANDARD};
+use hmac::digest::Digest;
+use ml_dsa::{
+    EncodedVerifyingKey, Error, KeyGen, MlDsa87, Seed, Signature as MlDsaSignature,
+    SigningKey as MlDsaSigningKey, VerifyingKey as MlDsaVerifyingKey, signature::Keypair as _,
+};
+
+pub static CLIENT_CONTEXT: &[u8] = b"arbiter_client";
+pub static USERAGENT_CONTEXT: &[u8] = b"arbiter_user_agent";
+
+pub fn format_challenge(nonce: i32, pubkey: &[u8]) -> Vec<u8> {
+    let concat_form = format!("{}:{}", nonce, BASE64_STANDARD.encode(pubkey));
+    concat_form.into_bytes()
+}
+
+pub type KeyParams = MlDsa87;
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct PublicKey(Box<MlDsaVerifyingKey<KeyParams>>);
+
+impl crate::hashing::Hashable for PublicKey {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        hasher.update(self.to_bytes());
+    }
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Signature(Box<MlDsaSignature<KeyParams>>);
+
+#[derive(Debug)]
+pub struct SigningKey(Box<MlDsaSigningKey<KeyParams>>);
+
+impl PublicKey {
+    pub fn to_bytes(&self) -> Vec<u8> {
+        self.0.encode().0.to_vec()
+    }
+
+    pub fn verify(&self, nonce: i32, context: &[u8], signature: &Signature) -> bool {
+        self.0.verify_with_context(
+            &format_challenge(nonce, &self.to_bytes()),
+            context,
+            &signature.0,
+        )
+    }
+}
+
+impl Signature {
+    pub fn to_bytes(&self) -> Vec<u8> {
+        self.0.encode().0.to_vec()
+    }
+}
+
+impl SigningKey {
+    pub fn generate() -> Self {
+        Self(Box::new(KeyParams::key_gen(&mut rand::rng())))
+    }
+
+    pub fn from_seed(seed: [u8; 32]) -> Self {
+        Self(Box::new(KeyParams::from_seed(&Seed::from(seed))))
+    }
+
+    pub fn to_seed(&self) -> [u8; 32] {
+        self.0.to_seed().into()
+    }
+
+    pub fn public_key(&self) -> PublicKey {
+        self.0.verifying_key().into()
+    }
+
+    pub fn sign_message(&self, message: &[u8], context: &[u8]) -> Result<Signature, Error> {
+        self.0
+            .signing_key()
+            .sign_deterministic(message, context)
+            .map(Into::into)
+    }
+
+    pub fn sign_challenge(&self, nonce: i32, context: &[u8]) -> Result<Signature, Error> {
+        self.sign_message(
+            &format_challenge(nonce, &self.public_key().to_bytes()),
+            context,
+        )
+    }
+}
+
+impl From<MlDsaVerifyingKey<KeyParams>> for PublicKey {
+    fn from(value: MlDsaVerifyingKey<KeyParams>) -> Self {
+        Self(Box::new(value))
+    }
+}
+
+impl From<MlDsaSignature<KeyParams>> for Signature {
+    fn from(value: MlDsaSignature<KeyParams>) -> Self {
+        Self(Box::new(value))
+    }
+}
+
+impl From<MlDsaSigningKey<KeyParams>> for SigningKey {
+    fn from(value: MlDsaSigningKey<KeyParams>) -> Self {
+        Self(Box::new(value))
+    }
+}
+
+impl TryFrom<Vec<u8>> for PublicKey {
+    type Error = ();
+
+    fn try_from(value: Vec<u8>) -> Result<Self, Self::Error> {
+        Self::try_from(value.as_slice())
+    }
+}
+
+impl TryFrom<&'_ [u8]> for PublicKey {
+    type Error = ();
+
+    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
+        let encoded = EncodedVerifyingKey::<KeyParams>::try_from(value).map_err(|_| ())?;
+        Ok(Self(Box::new(MlDsaVerifyingKey::decode(&encoded))))
+    }
+}
+
+impl TryFrom<Vec<u8>> for Signature {
+    type Error = ();
+
+    fn try_from(value: Vec<u8>) -> Result<Self, Self::Error> {
+        Self::try_from(value.as_slice())
+    }
+}
+
+impl TryFrom<&'_ [u8]> for Signature {
+    type Error = ();
+
+    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
+        MlDsaSignature::try_from(value)
+            .map(|sig| Self(Box::new(sig)))
+            .map_err(|_| ())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use ml_dsa::{KeyGen, MlDsa87, signature::Keypair as _};
+
+    use super::{CLIENT_CONTEXT, PublicKey, Signature, SigningKey, USERAGENT_CONTEXT};
+
+    #[test]
+    fn public_key_round_trip_decodes() {
+        let key = MlDsa87::key_gen(&mut rand::rng());
+        let encoded = PublicKey::from(key.verifying_key()).to_bytes();
+
+        let decoded = PublicKey::try_from(encoded.as_slice()).expect("public key should decode");
+
+        assert_eq!(decoded, PublicKey::from(key.verifying_key()));
+    }
+
+    #[test]
+    fn signature_round_trip_decodes() {
+        let key = SigningKey::generate();
+        let signature = key
+            .sign_message(b"challenge", CLIENT_CONTEXT)
+            .expect("signature should be created");
+
+        let decoded =
+            Signature::try_from(signature.to_bytes().as_slice()).expect("signature should decode");
+
+        assert_eq!(decoded, signature);
+    }
+
+    #[test]
+    fn challenge_verification_uses_context_and_canonical_key_bytes() {
+        let key = SigningKey::generate();
+        let public_key = key.public_key();
+        let nonce = 17;
+        let signature = key
+            .sign_challenge(nonce, CLIENT_CONTEXT)
+            .expect("signature should be created");
+
+        assert!(public_key.verify(nonce, CLIENT_CONTEXT, &signature));
+        assert!(!public_key.verify(nonce, USERAGENT_CONTEXT, &signature));
+    }
+
+    #[test]
+    fn signing_key_round_trip_seed_preserves_public_key_and_signing() {
+        let original = SigningKey::generate();
+        let restored = SigningKey::from_seed(original.to_seed());
+
+        assert_eq!(restored.public_key(), original.public_key());
+
+        let signature = restored
+            .sign_challenge(9, CLIENT_CONTEXT)
+            .expect("signature should be created");
+
+        assert!(restored.public_key().verify(9, CLIENT_CONTEXT, &signature));
+    }
+}
--- a/server/crates/arbiter-crypto/src/hashing.rs
+++ b/server/crates/arbiter-crypto/src/hashing.rs
@@ -0,0 +1,111 @@
+pub use hmac::digest::Digest;
+use std::collections::HashSet;
+
+/// Deterministically hash a value by feeding its fields into the hasher in a consistent order.
+#[diagnostic::on_unimplemented(
+    note = "for local types consider adding `#[derive(arbiter_macros::Hashable)]` to your `{Self}` type",
+    note = "for types from other crates check whether the crate offers a `Hashable` implementation"
+)]
+pub trait Hashable {
+    fn hash<H: Digest>(&self, hasher: &mut H);
+}
+
+macro_rules! impl_numeric {
+    ($($t:ty),*) => {
+        $(
+            impl Hashable for $t {
+                fn hash<H: Digest>(&self, hasher: &mut H) {
+                    hasher.update(&self.to_be_bytes());
+                }
+            }
+        )*
+    };
+}
+
+impl_numeric!(u8, u16, u32, u64, i8, i16, i32, i64);
+
+impl Hashable for &[u8] {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        hasher.update(self);
+    }
+}
+
+impl Hashable for String {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        hasher.update(self.as_bytes());
+    }
+}
+
+impl<T: Hashable + PartialOrd> Hashable for Vec<T> {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        let ref_sorted = {
+            let mut sorted = self.iter().collect::<Vec<_>>();
+            sorted.sort_by(|a, b| a.partial_cmp(b).unwrap());
+            sorted
+        };
+        for item in ref_sorted {
+            item.hash(hasher);
+        }
+    }
+}
+
+impl<T: Hashable + PartialOrd> Hashable for HashSet<T> {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        let ref_sorted = {
+            let mut sorted = self.iter().collect::<Vec<_>>();
+            sorted.sort_by(|a, b| a.partial_cmp(b).unwrap());
+            sorted
+        };
+        for item in ref_sorted {
+            item.hash(hasher);
+        }
+    }
+}
+
+impl<T: Hashable> Hashable for Option<T> {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        match self {
+            Some(value) => {
+                hasher.update([1]);
+                value.hash(hasher);
+            }
+            None => hasher.update([0]),
+        }
+    }
+}
+
+impl<T: Hashable> Hashable for Box<T> {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        self.as_ref().hash(hasher);
+    }
+}
+
+impl<T: Hashable> Hashable for &T {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        (*self).hash(hasher);
+    }
+}
+
+impl Hashable for alloy::primitives::Address {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        hasher.update(self.as_slice());
+    }
+}
+
+impl Hashable for alloy::primitives::U256 {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        hasher.update(self.to_be_bytes::<32>());
+    }
+}
+
+impl Hashable for chrono::Duration {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        hasher.update(self.num_seconds().to_be_bytes());
+    }
+}
+
+impl Hashable for chrono::DateTime<chrono::Utc> {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        hasher.update(self.timestamp_millis().to_be_bytes());
+    }
+}
--- a/server/crates/arbiter-crypto/src/lib.rs
+++ b/server/crates/arbiter-crypto/src/lib.rs
@@ -0,0 +1,5 @@
+#[cfg(feature = "authn")]
+pub mod authn;
+pub mod hashing;
+#[cfg(feature = "safecell")]
+pub mod safecell;
--- a/server/crates/arbiter-server/src/safe_cell.rs
+++ b/server/crates/arbiter-server/src/safe_cell.rs
@@ -105,6 +105,11 @@ impl<T> SafeCellHandle<T> for MemSafeCell<T> {

 fn abort_memory_breach(action: &str, err: &memsafe::error::MemoryError) -> ! {
    eprintln!("fatal {action}: {err}");
+    // SAFETY: Intentionally cause a segmentation fault to prevent further execution in a compromised state.
+    unsafe {
+        let unsafe_pointer = std::ptr::null_mut::<u8>();
+        std::ptr::write_volatile(unsafe_pointer, 0);
+    }
    std::process::abort();
 }

--- a/server/crates/arbiter-macros/Cargo.toml
+++ b/server/crates/arbiter-macros/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "arbiter-macros"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "2.0", features = ["derive", "fold", "full", "visit-mut"] }
+
+[dev-dependencies]
+arbiter-crypto = { path = "../arbiter-crypto" }
+
+[lints]
+workspace = true
--- a/server/crates/arbiter-macros/src/hashable.rs
+++ b/server/crates/arbiter-macros/src/hashable.rs
@@ -0,0 +1,133 @@
+use proc_macro2::{Span, TokenStream, TokenTree};
+use quote::quote;
+use syn::parse_quote;
+use syn::spanned::Spanned;
+use syn::{DataStruct, DeriveInput, Fields, Generics, Index};
+
+use crate::utils::{HASHABLE_TRAIT_PATH, HMAC_DIGEST_PATH};
+
+pub(crate) fn derive(input: &DeriveInput) -> TokenStream {
+    match &input.data {
+        syn::Data::Struct(struct_data) => hashable_struct(input, struct_data),
+        syn::Data::Enum(_) => {
+            syn::Error::new_spanned(input, "Hashable can currently be derived only for structs")
+                .to_compile_error()
+        }
+        syn::Data::Union(_) => {
+            syn::Error::new_spanned(input, "Hashable cannot be derived for unions")
+                .to_compile_error()
+        }
+    }
+}
+
+fn hashable_struct(input: &DeriveInput, struct_data: &syn::DataStruct) -> TokenStream {
+    let ident = &input.ident;
+    let hashable_trait = HASHABLE_TRAIT_PATH.to_path();
+    let hmac_digest = HMAC_DIGEST_PATH.to_path();
+    let generics = add_hashable_bounds(input.generics.clone(), &hashable_trait);
+    let field_accesses = collect_field_accesses(struct_data);
+    let hash_calls = build_hash_calls(&field_accesses, &hashable_trait);
+
+    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
+
+    quote! {
+        #[automatically_derived]
+        impl #impl_generics #hashable_trait for #ident #ty_generics #where_clause {
+            fn hash<H: #hmac_digest>(&self, hasher: &mut H) {
+                #(#hash_calls)*
+            }
+        }
+    }
+}
+
+fn add_hashable_bounds(mut generics: Generics, hashable_trait: &syn::Path) -> Generics {
+    for type_param in generics.type_params_mut() {
+        type_param.bounds.push(parse_quote!(#hashable_trait));
+    }
+
+    generics
+}
+
+struct FieldAccess {
+    access: TokenStream,
+    span: Span,
+}
+
+fn collect_field_accesses(struct_data: &DataStruct) -> Vec<FieldAccess> {
+    match &struct_data.fields {
+        Fields::Named(fields) => {
+            // Keep deterministic alphabetical order for named fields.
+            // Do not remove this sort, because it keeps hash output stable regardless of source order.
+            let mut named_fields = fields
+                .named
+                .iter()
+                .map(|field| {
+                    let name = field
+                        .ident
+                        .as_ref()
+                        .expect("Fields::Named(fields) must have names")
+                        .clone();
+                    (name.to_string(), name)
+                })
+                .collect::<Vec<_>>();
+
+            named_fields.sort_by(|a, b| a.0.cmp(&b.0));
+
+            named_fields
+                .into_iter()
+                .map(|(_, name)| FieldAccess {
+                    access: quote! { #name },
+                    span: name.span(),
+                })
+                .collect()
+        }
+        Fields::Unnamed(fields) => fields
+            .unnamed
+            .iter()
+            .enumerate()
+            .map(|(i, field)| FieldAccess {
+                access: {
+                    let index = Index::from(i);
+                    quote! { #index }
+                },
+                span: field.ty.span(),
+            })
+            .collect(),
+        Fields::Unit => Vec::new(),
+    }
+}
+
+fn build_hash_calls(
+    field_accesses: &[FieldAccess],
+    hashable_trait: &syn::Path,
+) -> Vec<TokenStream> {
+    field_accesses
+        .iter()
+        .map(|field| {
+            let access = &field.access;
+            let call = quote! {
+                #hashable_trait::hash(&self.#access, hasher);
+            };
+
+            respan(call, field.span)
+        })
+        .collect()
+}
+
+/// Recursively set span on all tokens, including interpolated ones.
+fn respan(tokens: TokenStream, span: Span) -> TokenStream {
+    tokens
+        .into_iter()
+        .map(|tt| match tt {
+            TokenTree::Group(g) => {
+                let mut new = proc_macro2::Group::new(g.delimiter(), respan(g.stream(), span));
+                new.set_span(span);
+                TokenTree::Group(new)
+            }
+            mut other => {
+                other.set_span(span);
+                other
+            }
+        })
+        .collect()
+}
--- a/server/crates/arbiter-macros/src/lib.rs
+++ b/server/crates/arbiter-macros/src/lib.rs
@@ -0,0 +1,10 @@
+use syn::{DeriveInput, parse_macro_input};
+
+mod hashable;
+mod utils;
+
+#[proc_macro_derive(Hashable)]
+pub fn derive_hashable(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+    hashable::derive(&input).into()
+}
--- a/server/crates/arbiter-macros/src/utils.rs
+++ b/server/crates/arbiter-macros/src/utils.rs
@@ -0,0 +1,19 @@
+pub struct ToPath(pub &'static str);
+
+impl ToPath {
+    pub fn to_path(&self) -> syn::Path {
+        syn::parse_str(self.0).expect("Invalid path")
+    }
+}
+
+macro_rules! ensure_path {
+    ($path:path) => {{
+        #[cfg(test)]
+        #[expect(unused_imports)]
+        use $path as _;
+        ToPath(stringify!($path))
+    }};
+}
+
+pub const HASHABLE_TRAIT_PATH: ToPath = ensure_path!(::arbiter_crypto::hashing::Hashable);
+pub const HMAC_DIGEST_PATH: ToPath = ensure_path!(::arbiter_crypto::hashing::Digest);
--- a/server/crates/arbiter-proto/Cargo.toml
+++ b/server/crates/arbiter-proto/Cargo.toml
@@ -11,13 +11,13 @@ tokio.workspace = true
 futures.workspace = true
 hex = "0.4.3"
 tonic-prost = "0.14.5"
-prost = "0.14.3"
+prost.workspace = true
 kameo.workspace = true
 url = "2.5.8"
 miette.workspace = true
 thiserror.workspace = true
 rustls-pki-types.workspace = true
-base64 = "0.22.1"
+base64.workspace = true
 prost-types.workspace = true
 tracing.workspace = true
 async-trait.workspace = true
--- a/server/crates/arbiter-proto/src/lib.rs
+++ b/server/crates/arbiter-proto/src/lib.rs
@@ -1,8 +1,6 @@
 pub mod transport;
 pub mod url;

-use base64::{Engine, prelude::BASE64_STANDARD};
-
 pub mod proto {
    tonic::include_proto!("arbiter");

@@ -84,8 +82,3 @@ pub fn home_path() -> Result<std::path::PathBuf, std::io::Error> {

    Ok(arbiter_home)
 }
-
-pub fn format_challenge(nonce: i32, pubkey: &[u8]) -> Vec<u8> {
-    let concat_form = format!("{}:{}", nonce, BASE64_STANDARD.encode(pubkey));
-    concat_form.into_bytes()
-}
--- a/server/crates/arbiter-server/Cargo.toml
+++ b/server/crates/arbiter-server/Cargo.toml
@@ -16,8 +16,9 @@ diesel-async = { version = "0.8.0", features = [
    "sqlite",
    "tokio",
 ] }
-ed25519-dalek.workspace = true
 arbiter-proto.path = "../arbiter-proto"
+arbiter-crypto.path = "../arbiter-crypto"
+arbiter-macros.path = "../arbiter-macros"
 tracing.workspace = true
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 tonic.workspace = true
@@ -36,25 +37,31 @@ dashmap = "6.1.0"
 rand.workspace = true
 rcgen.workspace = true
 chrono.workspace = true
-memsafe = "0.4.0"
 zeroize = { version = "1.8.2", features = ["std", "simd"] }
 kameo.workspace = true
-x25519-dalek.workspace = true
 chacha20poly1305 = { version = "0.10.1", features = ["std"] }
 argon2 = { version = "0.5.3", features = ["zeroize"] }
 restructed = "0.2.2"
 strum = { version = "0.28.0", features = ["derive"] }
 pem = "3.0.6"
-k256.workspace = true
-rsa.workspace = true
 sha2.workspace = true
-hmac = "0.12"
+hmac.workspace = true
 spki.workspace = true
 alloy.workspace = true
 prost-types.workspace = true
+prost.workspace = true
 arbiter-tokens-registry.path = "../arbiter-tokens-registry"
 anyhow = "1.0.102"
+serde_with = "3.18.0"
+mutants.workspace = true
+subtle = "2.6.1"
+ml-dsa.workspace = true
+ed25519-dalek.workspace = true
+x25519-dalek.workspace = true
+k256.workspace = true

 [dev-dependencies]
 insta = "1.46.3"
+proptest = "1.11.0"
+rstest.workspace = true
 test-log = { version = "0.2", default-features = false, features = ["trace"] }
--- a/server/crates/arbiter-server/migrations/2026-02-14-171124-0000_init/up.sql
+++ b/server/crates/arbiter-server/migrations/2026-02-14-171124-0000_init/up.sql
@@ -47,8 +47,7 @@ create table if not exists useragent_client (
    id integer not null primary key,
    nonce integer not null default(1), -- used for auth challenge
    public_key blob not null,
-    pubkey_integrity_tag blob,
-    key_type integer not null default(1), -- 1=Ed25519, 2=ECDSA(secp256k1)
+    key_type integer not null default(1),
    created_at integer not null default(unixepoch ('now')),
    updated_at integer not null default(unixepoch ('now'))
 ) STRICT;
@@ -192,3 +191,19 @@ create table if not exists evm_ether_transfer_grant_target (
 ) STRICT;

 create unique index if not exists uniq_ether_transfer_target on evm_ether_transfer_grant_target (grant_id, address);
+
+-- ===============================
+-- Integrity Envelopes
+-- ===============================
+create table if not exists integrity_envelope (
+    id integer not null primary key,
+    entity_kind text not null,
+    entity_id blob not null,
+    payload_version integer not null,
+    key_version integer not null,
+    mac blob not null, -- 20-byte recipient address
+    signed_at integer not null default(unixepoch ('now')),
+    created_at integer not null default(unixepoch ('now'))
+) STRICT;
+
+create unique index if not exists uniq_integrity_envelope_entity on integrity_envelope (entity_kind, entity_id);
--- a/server/crates/arbiter-server/src/actors/bootstrap.rs
+++ b/server/crates/arbiter-server/src/actors/bootstrap.rs
@@ -4,6 +4,7 @@ use diesel_async::RunQueryDsl;
 use kameo::{Actor, messages};

 use rand::{RngExt, distr::Alphanumeric, make_rng, rngs::StdRng};
+use subtle::ConstantTimeEq as _;
 use thiserror::Error;

 use crate::db::{self, DatabasePool, schema};
@@ -44,14 +45,14 @@ pub struct Bootstrapper {

 impl Bootstrapper {
    pub async fn new(db: &DatabasePool) -> Result<Self, Error> {
+        let row_count: i64 = {
            let mut conn = db.get().await?;

-        let row_count: i64 = schema::useragent_client::table
+            schema::useragent_client::table
                .count()
                .get_result(&mut conn)
-            .await?;
-
-        drop(conn);
+                .await?
+        };

        let token = if row_count == 0 {
            let token = generate_token().await?;
@@ -69,7 +70,13 @@ impl Bootstrapper {
    #[message]
    pub fn is_correct_token(&self, token: String) -> bool {
        match &self.token {
-            Some(expected) => *expected == token,
+            Some(expected) => {
+                let expected_bytes = expected.as_bytes();
+                let token_bytes = token.as_bytes();
+
+                let choice = expected_bytes.ct_eq(token_bytes);
+                bool::from(choice)
+            }
            None => false,
        }
    }
--- a/server/crates/arbiter-server/src/actors/client/auth.rs
+++ b/server/crates/arbiter-server/src/actors/client/auth.rs
@@ -1,5 +1,6 @@
+use arbiter_crypto::authn::{self, CLIENT_CONTEXT};
 use arbiter_proto::{
-    ClientMetadata, format_challenge,
+    ClientMetadata,
    transport::{Bi, expect_message},
 };
 use chrono::Utc;
@@ -8,15 +9,16 @@ use diesel::{
    dsl::insert_into, update,
 };
 use diesel_async::RunQueryDsl as _;
-use ed25519_dalek::{Signature, VerifyingKey};
-use kameo::error::SendError;
+use kameo::{actor::ActorRef, error::SendError};
 use tracing::error;

 use crate::{
    actors::{
-        client::{ClientConnection, ClientProfile},
+        client::{ClientConnection, ClientCredentials, ClientProfile},
        flow_coordinator::{self, RequestClientApproval},
+        keyholder::KeyHolder,
    },
+    crypto::integrity::{self, AttestationStatus},
    db::{
        self,
        models::{ProgramClientMetadata, SqliteTimestamp},
@@ -30,6 +32,8 @@ pub enum Error {
    DatabasePoolUnavailable,
    #[error("Database operation failed")]
    DatabaseOperationFailed,
+    #[error("Integrity check failed")]
+    IntegrityCheckFailed,
    #[error("Invalid challenge solution")]
    InvalidChallengeSolution,
    #[error("Client approval request failed")]
@@ -38,6 +42,13 @@ pub enum Error {
    Transport,
 }

+impl From<diesel::result::Error> for Error {
+    fn from(e: diesel::result::Error) -> Self {
+        error!(?e, "Database error");
+        Self::DatabaseOperationFailed
+    }
+}
+
 #[derive(thiserror::Error, Debug, Clone, PartialEq, Eq)]
 pub enum ApproveError {
    #[error("Internal error")]
@@ -51,32 +62,93 @@ pub enum ApproveError {
 #[derive(Debug, Clone)]
 pub enum Inbound {
    AuthChallengeRequest {
-        pubkey: VerifyingKey,
+        pubkey: authn::PublicKey,
        metadata: ClientMetadata,
    },
    AuthChallengeSolution {
-        signature: Signature,
+        signature: authn::Signature,
    },
 }

 #[derive(Debug, Clone)]
 pub enum Outbound {
-    AuthChallenge { pubkey: VerifyingKey, nonce: i32 },
+    AuthChallenge {
+        pubkey: authn::PublicKey,
+        nonce: i32,
+    },
    AuthSuccess,
 }

-pub struct ClientInfo {
-    pub id: i32,
-    pub current_nonce: i32,
+/// Returns the current nonce and client ID for a registered client.
+/// Returns `None` if the pubkey is not registered.
+async fn get_current_nonce_and_id(
+    db: &db::DatabasePool,
+    pubkey: &authn::PublicKey,
+) -> Result<Option<(i32, i32)>, Error> {
+    let pubkey_bytes = pubkey.to_bytes();
+    let mut conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::DatabasePoolUnavailable
+    })?;
+    program_client::table
+        .filter(program_client::public_key.eq(&pubkey_bytes))
+        .select((program_client::id, program_client::nonce))
+        .first::<(i32, i32)>(&mut conn)
+        .await
+        .optional()
+        .map_err(|e| {
+            error!(error = ?e, "Database error");
+            Error::DatabaseOperationFailed
+        })
 }

-/// Atomically reads and increments the nonce for a known client.
-/// Returns `None` if the pubkey is not registered.
-async fn get_client_and_nonce(
+async fn verify_integrity(
    db: &db::DatabasePool,
-    pubkey: &VerifyingKey,
-) -> Result<Option<ClientInfo>, Error> {
-    let pubkey_bytes = pubkey.as_bytes().to_vec();
+    keyholder: &ActorRef<KeyHolder>,
+    pubkey: &authn::PublicKey,
+) -> Result<(), Error> {
+    let mut db_conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::DatabasePoolUnavailable
+    })?;
+
+    let (id, nonce) = get_current_nonce_and_id(db, pubkey).await?.ok_or_else(|| {
+        error!("Client not found during integrity verification");
+        Error::DatabaseOperationFailed
+    })?;
+
+    let attestation = integrity::verify_entity(
+        &mut db_conn,
+        keyholder,
+        &ClientCredentials {
+            pubkey: pubkey.clone(),
+            nonce,
+        },
+        id,
+    )
+    .await
+    .map_err(|e| {
+        error!(?e, "Integrity verification failed");
+        Error::IntegrityCheckFailed
+    })?;
+
+    if attestation != AttestationStatus::Attested {
+        error!("Integrity attestation unavailable for client {id}");
+        return Err(Error::IntegrityCheckFailed);
+    }
+
+    Ok(())
+}
+
+/// Atomically increments the nonce and re-signs the integrity envelope.
+/// Returns the new nonce, which is used as the challenge nonce.
+async fn create_nonce(
+    db: &db::DatabasePool,
+    keyholder: &ActorRef<KeyHolder>,
+    pubkey: &authn::PublicKey,
+) -> Result<i32, Error> {
+    let pubkey_bytes = pubkey.to_bytes();
+    let pubkey = pubkey.clone();

    let mut conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
@@ -84,34 +156,35 @@ async fn get_client_and_nonce(
    })?;

    conn.exclusive_transaction(|conn| {
+        let keyholder = keyholder.clone();
+        let pubkey = pubkey.clone();
        Box::pin(async move {
-            let Some((client_id, current_nonce)) = program_client::table
+            let (id, new_nonce): (i32, i32) = update(program_client::table)
                .filter(program_client::public_key.eq(&pubkey_bytes))
-                .select((program_client::id, program_client::nonce))
-                .first::<(i32, i32)>(conn)
-                .await
-                .optional()?
-            else {
-                return Result::<_, diesel::result::Error>::Ok(None);
-            };
-
-            update(program_client::table)
-                .filter(program_client::public_key.eq(&pubkey_bytes))
-                .set(program_client::nonce.eq(current_nonce + 1))
-                .execute(conn)
+                .set(program_client::nonce.eq(program_client::nonce + 1))
+                .returning((program_client::id, program_client::nonce))
+                .get_result(conn)
                .await?;

-            Ok(Some(ClientInfo {
-                id: client_id,
-                current_nonce,
-            }))
+            integrity::sign_entity(
+                conn,
+                &keyholder,
+                &ClientCredentials {
+                    pubkey: pubkey.clone(),
+                    nonce: new_nonce,
+                },
+                id,
+            )
+            .await
+            .map_err(|e| {
+                error!(?e, "Integrity sign failed after nonce update");
+                Error::DatabaseOperationFailed
+            })?;
+
+            Ok(new_nonce)
        })
    })
    .await
-    .map_err(|e| {
-        error!(error = ?e, "Database error");
-        Error::DatabaseOperationFailed
-    })
 }

 async fn approve_new_client(
@@ -139,15 +212,25 @@ async fn approve_new_client(

 async fn insert_client(
    db: &db::DatabasePool,
-    pubkey: &VerifyingKey,
+    keyholder: &ActorRef<KeyHolder>,
+    pubkey: &authn::PublicKey,
    metadata: &ClientMetadata,
 ) -> Result<i32, Error> {
    use crate::db::schema::{client_metadata, program_client};
+    let pubkey = pubkey.clone();
+    let metadata = metadata.clone();
+
    let mut conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
        Error::DatabasePoolUnavailable
    })?;

+    conn.exclusive_transaction(|conn| {
+        let keyholder = keyholder.clone();
+        let pubkey = pubkey.clone();
+        Box::pin(async move {
+            const NONCE_START: i32 = 1;
+
            let metadata_id = insert_into(client_metadata::table)
                .values((
                    client_metadata::name.eq(&metadata.name),
@@ -155,29 +238,39 @@ async fn insert_client(
                    client_metadata::version.eq(&metadata.version),
                ))
                .returning(client_metadata::id)
-        .get_result::<i32>(&mut conn)
-        .await
-        .map_err(|e| {
-            error!(error = ?e, "Failed to insert client metadata");
-            Error::DatabaseOperationFailed
-        })?;
+                .get_result::<i32>(conn)
+                .await?;

            let client_id = insert_into(program_client::table)
                .values((
-            program_client::public_key.eq(pubkey.as_bytes().to_vec()),
+                    program_client::public_key.eq(pubkey.to_bytes()),
                    program_client::metadata_id.eq(metadata_id),
-            program_client::nonce.eq(1), // pre-incremented; challenge uses 0
+                    program_client::nonce.eq(NONCE_START),
                ))
                .on_conflict_do_nothing()
                .returning(program_client::id)
-        .get_result::<i32>(&mut conn)
+                .get_result::<i32>(conn)
+                .await?;
+
+            integrity::sign_entity(
+                conn,
+                &keyholder,
+                &ClientCredentials {
+                    pubkey: pubkey.clone(),
+                    nonce: NONCE_START,
+                },
+                client_id,
+            )
            .await
            .map_err(|e| {
-            error!(error = ?e, "Failed to insert client metadata");
+                error!(error = ?e, "Failed to sign integrity tag for new client key");
                Error::DatabaseOperationFailed
            })?;

            Ok(client_id)
+        })
+    })
+    .await
 }

 async fn sync_client_metadata(
@@ -253,14 +346,17 @@ async fn sync_client_metadata(

 async fn challenge_client<T>(
    transport: &mut T,
-    pubkey: VerifyingKey,
+    pubkey: authn::PublicKey,
    nonce: i32,
 ) -> Result<(), Error>
 where
    T: Bi<Inbound, Result<Outbound, Error>> + ?Sized,
 {
    transport
-        .send(Ok(Outbound::AuthChallenge { pubkey, nonce }))
+        .send(Ok(Outbound::AuthChallenge {
+            pubkey: pubkey.clone(),
+            nonce,
+        }))
        .await
        .map_err(|e| {
            error!(error = ?e, "Failed to send auth challenge");
@@ -277,12 +373,10 @@ where
        Error::Transport
    })?;

-    let formatted = format_challenge(nonce, pubkey.as_bytes());
-
-    pubkey.verify_strict(&formatted, &signature).map_err(|_| {
+    if !pubkey.verify(nonce, CLIENT_CONTEXT, &signature) {
        error!("Challenge solution verification failed");
-        Error::InvalidChallengeSolution
-    })?;
+        return Err(Error::InvalidChallengeSolution);
+    }

    Ok(())
 }
@@ -295,27 +389,27 @@ where
        return Err(Error::Transport);
    };

-    let info = match get_client_and_nonce(&props.db, &pubkey).await? {
-        Some(nonce) => nonce,
+    let client_id = match get_current_nonce_and_id(&props.db, &pubkey).await? {
+        Some((id, _)) => {
+            verify_integrity(&props.db, &props.actors.key_holder, &pubkey).await?;
+            id
+        }
        None => {
            approve_new_client(
                &props.actors,
                ClientProfile {
-                    pubkey,
+                    pubkey: pubkey.clone(),
                    metadata: metadata.clone(),
                },
            )
            .await?;
-            let client_id = insert_client(&props.db, &pubkey, &metadata).await?;
-            ClientInfo {
-                id: client_id,
-                current_nonce: 0,
-            }
+            insert_client(&props.db, &props.actors.key_holder, &pubkey, &metadata).await?
        }
    };

-    sync_client_metadata(&props.db, info.id, &metadata).await?;
-    challenge_client(transport, pubkey, info.current_nonce).await?;
+    sync_client_metadata(&props.db, client_id, &metadata).await?;
+    let challenge_nonce = create_nonce(&props.db, &props.actors.key_holder, &pubkey).await?;
+    challenge_client(transport, pubkey, challenge_nonce).await?;

    transport
        .send(Ok(Outbound::AuthSuccess))
@@ -325,5 +419,5 @@ where
            Error::Transport
        })?;

-    Ok(info.id)
+    Ok(client_id)
 }
--- a/server/crates/arbiter-server/src/actors/client/mod.rs
+++ b/server/crates/arbiter-server/src/actors/client/mod.rs
@@ -1,18 +1,30 @@
+use arbiter_crypto::authn;
 use arbiter_proto::{ClientMetadata, transport::Bi};
 use kameo::actor::Spawn;
 use tracing::{error, info};

 use crate::{
    actors::{GlobalActors, client::session::ClientSession},
+    crypto::integrity::Integrable,
    db,
 };

 #[derive(Debug, Clone)]
 pub struct ClientProfile {
-    pub pubkey: ed25519_dalek::VerifyingKey,
+    pub pubkey: authn::PublicKey,
    pub metadata: ClientMetadata,
 }

+#[derive(arbiter_macros::Hashable)]
+pub struct ClientCredentials {
+    pub pubkey: authn::PublicKey,
+    pub nonce: i32,
+}
+
+impl Integrable for ClientCredentials {
+    const KIND: &'static str = "client_credentials";
+}
+
 pub struct ClientConnection {
    pub(crate) db: db::DatabasePool,
    pub(crate) actors: GlobalActors,
@@ -31,7 +43,9 @@ pub async fn connect_client<T>(mut props: ClientConnection, transport: &mut T)
 where
    T: Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> + Send + ?Sized,
 {
-    match auth::authenticate(&mut props, transport).await {
+    let fut = auth::authenticate(&mut props, transport);
+    println!("authenticate future size: {}", std::mem::size_of_val(&fut));
+    match fut.await {
        Ok(client_id) => {
            ClientSession::spawn(ClientSession::new(props, client_id));
            info!("Client authenticated, session started");
--- a/server/crates/arbiter-server/src/actors/evm/mod.rs
+++ b/server/crates/arbiter-server/src/actors/evm/mod.rs
@@ -8,20 +8,21 @@ use rand::{SeedableRng, rng, rngs::StdRng};

 use crate::{
    actors::keyholder::{CreateNew, Decrypt, KeyHolder},
+    crypto::integrity,
    db::{
        DatabaseError, DatabasePool,
-        models::{self, SqliteTimestamp},
+        models::{self},
        schema,
    },
    evm::{
-        self, RunKind,
+        self, ListError, RunKind,
        policies::{
-            FullGrant, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning,
+            CombinedSettings, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning,
            ether_transfer::EtherTransfer, token_transfers::TokenTransfer,
        },
    },
-    safe_cell::{SafeCell, SafeCellHandle as _},
 };
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

 pub use crate::evm::safe_signer;

@@ -56,6 +57,9 @@ pub enum Error {

    #[error("Database error: {0}")]
    Database(#[from] DatabaseError),
+
+    #[error("Integrity violation: {0}")]
+    Integrity(#[from] integrity::Error),
 }

 #[derive(Actor)]
@@ -71,7 +75,7 @@ impl EvmActor {
        // is it safe to seed rng from system once?
        // todo: audit
        let rng = StdRng::from_rng(&mut rng());
-        let engine = evm::Engine::new(db.clone());
+        let engine = evm::Engine::new(db.clone(), keyholder.clone());
        Self {
            keyholder,
            db,
@@ -132,46 +136,59 @@ impl EvmActor {
        &mut self,
        basic: SharedGrantSettings,
        grant: SpecificGrant,
-    ) -> Result<i32, DatabaseError> {
+    ) -> Result<i32, Error> {
        match grant {
-            SpecificGrant::EtherTransfer(settings) => {
-                self.engine
-                    .create_grant::<EtherTransfer>(FullGrant {
-                        basic,
+            SpecificGrant::EtherTransfer(settings) => self
+                .engine
+                .create_grant::<EtherTransfer>(CombinedSettings {
+                    shared: basic,
                    specific: settings,
                })
                .await
-            }
-            SpecificGrant::TokenTransfer(settings) => {
-                self.engine
-                    .create_grant::<TokenTransfer>(FullGrant {
-                        basic,
+                .map_err(Error::from),
+            SpecificGrant::TokenTransfer(settings) => self
+                .engine
+                .create_grant::<TokenTransfer>(CombinedSettings {
+                    shared: basic,
                    specific: settings,
                })
                .await
-            }
+                .map_err(Error::from),
        }
    }

    #[message]
-    pub async fn useragent_delete_grant(&mut self, grant_id: i32) -> Result<(), Error> {
-        let mut conn = self.db.get().await.map_err(DatabaseError::from)?;
-        diesel::update(schema::evm_basic_grant::table)
-            .filter(schema::evm_basic_grant::id.eq(grant_id))
-            .set(schema::evm_basic_grant::revoked_at.eq(SqliteTimestamp::now()))
-            .execute(&mut conn)
-            .await
-            .map_err(DatabaseError::from)?;
-        Ok(())
+    pub async fn useragent_delete_grant(&mut self, _grant_id: i32) -> Result<(), Error> {
+        // let mut conn = self.db.get().await.map_err(DatabaseError::from)?;
+        // let keyholder = self.keyholder.clone();
+
+        // diesel_async::AsyncConnection::transaction(&mut conn, |conn| {
+        //     Box::pin(async move {
+        //         diesel::update(schema::evm_basic_grant::table)
+        //             .filter(schema::evm_basic_grant::id.eq(grant_id))
+        //             .set(schema::evm_basic_grant::revoked_at.eq(SqliteTimestamp::now()))
+        //             .execute(conn)
+        //             .await?;
+
+        //         let signed = integrity::evm::load_signed_grant_by_basic_id(conn, grant_id).await?;
+
+        //         diesel::result::QueryResult::Ok(())
+        //     })
+        // })
+        // .await
+        // .map_err(DatabaseError::from)?;
+
+        // Ok(())
+        todo!()
    }

    #[message]
    pub async fn useragent_list_grants(&mut self) -> Result<Vec<Grant<SpecificGrant>>, Error> {
-        Ok(self
-            .engine
-            .list_all_grants()
-            .await
-            .map_err(DatabaseError::from)?)
+        match self.engine.list_all_grants().await {
+            Ok(grants) => Ok(grants),
+            Err(ListError::Database(db_err)) => Err(Error::Database(db_err)),
+            Err(ListError::Integrity(integrity_err)) => Err(Error::Integrity(integrity_err)),
+        }
    }

    #[message]
--- a/server/crates/arbiter-server/src/actors/keyholder/mod.rs
+++ b/server/crates/arbiter-server/src/actors/keyholder/mod.rs
@@ -4,26 +4,22 @@ use diesel::{
    dsl::{insert_into, update},
 };
 use diesel_async::{AsyncConnection, RunQueryDsl};
+use hmac::Mac as _;
 use kameo::{Actor, Reply, messages};
 use strum::{EnumDiscriminants, IntoDiscriminant};
 use tracing::{error, info};

-use crate::{
-    crypto::{
+use crate::crypto::{
    KeyCell, derive_key,
    encryption::v1::{self, Nonce},
-        integrity::v1::compute_integrity_tag,
-    },
-    safe_cell::SafeCell,
+    integrity::v1::HmacSha256,
 };
-use crate::{
-    db::{
+use crate::db::{
    self,
    models::{self, RootKeyHistory},
    schema::{self},
-    },
-    safe_cell::SafeCellHandle as _,
 };
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

 #[derive(Default, EnumDiscriminants)]
 #[strum_discriminants(derive(Reply), vis(pub), name(KeyHolderState))]
@@ -250,22 +246,6 @@ impl KeyHolder {
        Ok(())
    }

-    // Signs a generic integrity payload using the vault-derived integrity key
-    #[message]
-    pub fn sign_integrity_tag(
-        &mut self,
-        purpose_tag: Vec<u8>,
-        data_parts: Vec<Vec<u8>>,
-    ) -> Result<Vec<u8>, Error> {
-        let State::Unsealed { root_key, .. } = &mut self.state else {
-            return Err(Error::NotBootstrapped);
-        };
-
-        let tag =
-            compute_integrity_tag(root_key, &purpose_tag, data_parts.iter().map(Vec::as_slice));
-        Ok(tag.to_vec())
-    }
-
    #[message]
    pub async fn decrypt(&mut self, aead_id: i32) -> Result<SafeCell<Vec<u8>>, Error> {
        let State::Unsealed { root_key, .. } = &mut self.state else {
@@ -339,6 +319,60 @@ impl KeyHolder {
        self.state.discriminant()
    }

+    #[message]
+    pub fn sign_integrity(&mut self, mac_input: Vec<u8>) -> Result<(i32, Vec<u8>), Error> {
+        let State::Unsealed {
+            root_key,
+            root_key_history_id,
+        } = &mut self.state
+        else {
+            return Err(Error::NotBootstrapped);
+        };
+
+        let mut hmac = root_key
+            .0
+            .read_inline(|k| match HmacSha256::new_from_slice(k) {
+                Ok(v) => v,
+                Err(_) => unreachable!("HMAC accepts keys of any size"),
+            });
+        hmac.update(&root_key_history_id.to_be_bytes());
+        hmac.update(&mac_input);
+
+        let mac = hmac.finalize().into_bytes().to_vec();
+        Ok((*root_key_history_id, mac))
+    }
+
+    #[message]
+    pub fn verify_integrity(
+        &mut self,
+        mac_input: Vec<u8>,
+        expected_mac: Vec<u8>,
+        key_version: i32,
+    ) -> Result<bool, Error> {
+        let State::Unsealed {
+            root_key,
+            root_key_history_id,
+        } = &mut self.state
+        else {
+            return Err(Error::NotBootstrapped);
+        };
+
+        if *root_key_history_id != key_version {
+            return Ok(false);
+        }
+
+        let mut hmac = root_key
+            .0
+            .read_inline(|k| match HmacSha256::new_from_slice(k) {
+                Ok(v) => v,
+                Err(_) => unreachable!("HMAC accepts keys of any size"),
+            });
+        hmac.update(&key_version.to_be_bytes());
+        hmac.update(&mac_input);
+
+        Ok(hmac.verify_slice(&expected_mac).is_ok())
+    }
+
    #[message]
    pub fn seal(&mut self) -> Result<(), Error> {
        let State::Unsealed {
@@ -361,10 +395,8 @@ mod tests {

    use diesel_async::RunQueryDsl;

-    use crate::{
-        db::{self},
-        safe_cell::SafeCell,
-    };
+    use crate::db::{self};
+    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

    use super::*;

--- a/server/crates/arbiter-server/src/actors/user_agent/auth.rs
+++ b/server/crates/arbiter-server/src/actors/user_agent/auth.rs
@@ -1,18 +1,18 @@
+use arbiter_crypto::authn;
 use arbiter_proto::transport::Bi;
 use tracing::error;

 use crate::actors::user_agent::{
-    AuthPublicKey, UserAgentConnection,
+    UserAgentConnection,
    auth::state::{AuthContext, AuthStateMachine},
 };
-
 mod state;
 use state::*;

 #[derive(Debug, Clone)]
 pub enum Inbound {
    AuthChallengeRequest {
-        pubkey: AuthPublicKey,
+        pubkey: authn::PublicKey,
        bootstrap_token: Option<String>,
    },
    AuthChallengeSolution {
@@ -37,6 +37,13 @@ impl Error {
    }
 }

+impl From<diesel::result::Error> for Error {
+    fn from(e: diesel::result::Error) -> Self {
+        error!(?e, "Database error");
+        Self::internal("Database error")
+    }
+}
+
 #[derive(Debug, Clone)]
 pub enum Outbound {
    AuthChallenge { nonce: i32 },
@@ -64,7 +71,7 @@ fn parse_auth_event(payload: Inbound) -> AuthEvents {
 pub async fn authenticate<T>(
    props: &mut UserAgentConnection,
    transport: T,
-) -> Result<AuthPublicKey, Error>
+) -> Result<authn::PublicKey, Error>
 where
    T: Bi<Inbound, Result<Outbound, Error>> + Send,
 {
--- a/server/crates/arbiter-server/src/actors/user_agent/auth/state.rs
+++ b/server/crates/arbiter-server/src/actors/user_agent/auth/state.rs
@@ -1,39 +1,33 @@
+use arbiter_crypto::authn::{self, USERAGENT_CONTEXT};
 use arbiter_proto::transport::Bi;
 use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, update};
-use diesel_async::RunQueryDsl;
-use kameo::error::SendError;
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use kameo::actor::ActorRef;
 use tracing::error;

 use super::Error;
 use crate::{
    actors::{
        bootstrap::ConsumeToken,
-        keyholder::{self, SignIntegrityTag},
-        user_agent::{AuthPublicKey, UserAgentConnection, auth::Outbound},
+        keyholder::KeyHolder,
+        user_agent::{UserAgentConnection, UserAgentCredentials, auth::Outbound},
    },
-    crypto::integrity::v1::USERAGENT_INTEGRITY_TAG,
-    db::schema,
+    crypto::integrity,
+    db::{DatabasePool, schema::useragent_client},
 };

-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum AttestationStatus {
-    Attested,
-    NotAttested,
-    Unavailable,
-}
-
 pub struct ChallengeRequest {
-    pub pubkey: AuthPublicKey,
+    pub pubkey: authn::PublicKey,
 }

 pub struct BootstrapAuthRequest {
-    pub pubkey: AuthPublicKey,
+    pub pubkey: authn::PublicKey,
    pub token: String,
 }

 pub struct ChallengeContext {
    pub challenge_nonce: i32,
-    pub key: AuthPublicKey,
+    pub key: authn::PublicKey,
 }

 pub struct ChallengeSolution {
@@ -45,16 +39,16 @@ smlang::statemachine!(
    custom_error: true,
    transitions: {
        *Init + AuthRequest(ChallengeRequest) / async prepare_challenge = SentChallenge(ChallengeContext),
-        Init + BootstrapAuthRequest(BootstrapAuthRequest) / async verify_bootstrap_token = AuthOk(AuthPublicKey),
-        SentChallenge(ChallengeContext) + ReceivedSolution(ChallengeSolution) / async verify_solution = AuthOk(AuthPublicKey),
+        Init + BootstrapAuthRequest(BootstrapAuthRequest) / async verify_bootstrap_token = AuthOk(authn::PublicKey),
+        SentChallenge(ChallengeContext) + ReceivedSolution(ChallengeSolution) / async verify_solution = AuthOk(authn::PublicKey),
    }
 );

-async fn create_nonce(
-    db: &crate::db::DatabasePool,
-    pubkey_bytes: &[u8],
-    key_type: crate::db::models::KeyType,
-) -> Result<i32, Error> {
+/// Returns the current nonce, ready to use for the challenge nonce.
+async fn get_current_nonce_and_id(
+    db: &DatabasePool,
+    key: &authn::PublicKey,
+) -> Result<(i32, i32), Error> {
    let mut db_conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
        Error::internal("Database unavailable")
@@ -62,21 +56,11 @@ async fn create_nonce(
    db_conn
        .exclusive_transaction(|conn| {
            Box::pin(async move {
-                let current_nonce = schema::useragent_client::table
-                    .filter(schema::useragent_client::public_key.eq(pubkey_bytes.to_vec()))
-                    .filter(schema::useragent_client::key_type.eq(key_type))
-                    .select(schema::useragent_client::nonce)
-                    .first::<i32>(conn)
-                    .await?;
-
-                update(schema::useragent_client::table)
-                    .filter(schema::useragent_client::public_key.eq(pubkey_bytes.to_vec()))
-                    .filter(schema::useragent_client::key_type.eq(key_type))
-                    .set(schema::useragent_client::nonce.eq(current_nonce + 1))
-                    .execute(conn)
-                    .await?;
-
-                Result::<_, diesel::result::Error>::Ok(current_nonce)
+                useragent_client::table
+                    .filter(useragent_client::public_key.eq(key.to_bytes()))
+                    .select((useragent_client::id, useragent_client::nonce))
+                    .first::<(i32, i32)>(conn)
+                    .await
            })
        })
        .await
@@ -86,37 +70,131 @@ async fn create_nonce(
            Error::internal("Database operation failed")
        })?
        .ok_or_else(|| {
-            error!(?pubkey_bytes, "Public key not found in database");
+            error!(?key, "Public key not found in database");
            Error::UnregisteredPublicKey
        })
 }

-async fn register_key(
-    db: &crate::db::DatabasePool,
-    pubkey: &AuthPublicKey,
-    integrity_tag: Option<Vec<u8>>,
+async fn verify_integrity(
+    db: &DatabasePool,
+    keyholder: &ActorRef<KeyHolder>,
+    pubkey: &authn::PublicKey,
 ) -> Result<(), Error> {
-    let pubkey_bytes = pubkey.to_stored_bytes();
-    let key_type = pubkey.key_type();
-    let mut conn = db.get().await.map_err(|e| {
+    let mut db_conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
        Error::internal("Database unavailable")
    })?;

-    diesel::insert_into(schema::useragent_client::table)
-        .values((
-            schema::useragent_client::public_key.eq(pubkey_bytes),
-            schema::useragent_client::nonce.eq(1),
-            schema::useragent_client::key_type.eq(key_type),
-            schema::useragent_client::pubkey_integrity_tag.eq(integrity_tag),
-        ))
-        .execute(&mut conn)
+    let (id, nonce) = get_current_nonce_and_id(db, pubkey).await?;
+
+    let _result = integrity::verify_entity(
+        &mut db_conn,
+        keyholder,
+        &UserAgentCredentials {
+            pubkey: pubkey.clone(),
+            nonce,
+        },
+        id,
+    )
+    .await
+    .map_err(|e| {
+        error!(?e, "Integrity verification failed");
+        Error::internal("Integrity verification failed")
+    })?;
+
+    Ok(())
+}
+
+async fn create_nonce(
+    db: &DatabasePool,
+    keyholder: &ActorRef<KeyHolder>,
+    pubkey: &authn::PublicKey,
+) -> Result<i32, Error> {
+    let mut db_conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::internal("Database unavailable")
+    })?;
+    let new_nonce = db_conn
+        .exclusive_transaction(|conn| {
+            Box::pin(async move {
+                let (id, new_nonce): (i32, i32) = update(useragent_client::table)
+                    .filter(useragent_client::public_key.eq(pubkey.to_bytes()))
+                    .set(useragent_client::nonce.eq(useragent_client::nonce + 1))
+                    .returning((useragent_client::id, useragent_client::nonce))
+                    .get_result(conn)
                    .await
                    .map_err(|e| {
                        error!(error = ?e, "Database error");
                        Error::internal("Database operation failed")
                    })?;

+                integrity::sign_entity(
+                    conn,
+                    keyholder,
+                    &UserAgentCredentials {
+                        pubkey: pubkey.clone(),
+                        nonce: new_nonce,
+                    },
+                    id,
+                )
+                .await
+                .map_err(|e| {
+                    error!(?e, "Integrity signature update failed");
+                    Error::internal("Database error")
+                })?;
+
+                Result::<_, Error>::Ok(new_nonce)
+            })
+        })
+        .await?;
+    Ok(new_nonce)
+}
+
+async fn register_key(
+    db: &DatabasePool,
+    keyholder: &ActorRef<KeyHolder>,
+    pubkey: &authn::PublicKey,
+) -> Result<(), Error> {
+    let pubkey_bytes = pubkey.to_bytes();
+    let mut conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::internal("Database unavailable")
+    })?;
+
+    conn.transaction(|conn| {
+        Box::pin(async move {
+            const NONCE_START: i32 = 1;
+
+            let id: i32 = diesel::insert_into(useragent_client::table)
+                .values((
+                    useragent_client::public_key.eq(pubkey_bytes),
+                    useragent_client::nonce.eq(NONCE_START),
+                ))
+                .returning(useragent_client::id)
+                .get_result(conn)
+                .await
+                .map_err(|e| {
+                    error!(error = ?e, "Database error");
+                    Error::internal("Database operation failed")
+                })?;
+
+            let entity = UserAgentCredentials {
+                pubkey: pubkey.clone(),
+                nonce: NONCE_START,
+            };
+
+            integrity::sign_entity(conn, keyholder, &entity, id)
+                .await
+                .map_err(|e| {
+                    error!(error = ?e, "Failed to sign integrity tag for new user-agent key");
+                    Error::internal("Failed to register public key")
+                })?;
+
+            Result::<_, Error>::Ok(())
+        })
+    })
+    .await?;
+
    Ok(())
 }

@@ -141,15 +219,9 @@ where
        &mut self,
        ChallengeRequest { pubkey }: ChallengeRequest,
    ) -> Result<ChallengeContext, Self::Error> {
-        match self.verify_pubkey_attestation_status(&pubkey).await? {
-            AttestationStatus::Attested | AttestationStatus::Unavailable => {}
-            AttestationStatus::NotAttested => {
-                return Err(Error::InvalidChallengeSolution);
-            }
-        }
+        verify_integrity(&self.conn.db, &self.conn.actors.key_holder, &pubkey).await?;

-        let stored_bytes = pubkey.to_stored_bytes();
-        let nonce = create_nonce(&self.conn.db, &stored_bytes, pubkey.key_type()).await?;
+        let nonce = create_nonce(&self.conn.db, &self.conn.actors.key_holder, &pubkey).await?;

        self.transport
            .send(Ok(Outbound::AuthChallenge { nonce }))
@@ -170,7 +242,7 @@ where
    async fn verify_bootstrap_token(
        &mut self,
        BootstrapAuthRequest { pubkey, token }: BootstrapAuthRequest,
-    ) -> Result<AuthPublicKey, Self::Error> {
+    ) -> Result<authn::PublicKey, Self::Error> {
        let token_ok: bool = self
            .conn
            .actors
@@ -189,23 +261,25 @@ where
            return Err(Error::InvalidBootstrapToken);
        }

-        let integrity_tag = self
-            .try_sign_pubkey_integrity_tag(&pubkey)
-            .await
-            .map_err(|err| {
-                error!(?err, "Failed to sign user-agent pubkey integrity tag");
-                Error::internal("Failed to sign user-agent pubkey integrity tag")
-            })?;
-
-        register_key(&self.conn.db, &pubkey, integrity_tag).await?;
-
+        match token_ok {
+            true => {
+                register_key(&self.conn.db, &self.conn.actors.key_holder, &pubkey).await?;
                self.transport
                    .send(Ok(Outbound::AuthSuccess))
                    .await
                    .map_err(|_| Error::Transport)?;
-
                Ok(pubkey)
            }
+            false => {
+                error!("Invalid bootstrap token provided");
+                self.transport
+                    .send(Err(Error::InvalidBootstrapToken))
+                    .await
+                    .map_err(|_| Error::Transport)?;
+                Err(Error::InvalidBootstrapToken)
+            }
+        }
+    }

    #[allow(missing_docs)]
    #[allow(clippy::unused_unit)]
@@ -216,35 +290,13 @@ where
            key,
        }: &ChallengeContext,
        ChallengeSolution { solution }: ChallengeSolution,
-    ) -> Result<AuthPublicKey, Self::Error> {
-        let formatted = arbiter_proto::format_challenge(*challenge_nonce, &key.to_stored_bytes());
+    ) -> Result<authn::PublicKey, Self::Error> {
+        let signature = authn::Signature::try_from(solution.as_slice()).map_err(|_| {
+            error!("Failed to decode signature in challenge solution");
+            Error::InvalidChallengeSolution
+        })?;

-        let valid = match key {
-            AuthPublicKey::Ed25519(vk) => {
-                let sig = solution.as_slice().try_into().map_err(|_| {
-                    error!(?solution, "Invalid Ed25519 signature length");
-                    Error::InvalidChallengeSolution
-                })?;
-                vk.verify_strict(&formatted, &sig).is_ok()
-            }
-            AuthPublicKey::EcdsaSecp256k1(vk) => {
-                use k256::ecdsa::signature::Verifier as _;
-                let sig = k256::ecdsa::Signature::try_from(solution.as_slice()).map_err(|_| {
-                    error!(?solution, "Invalid ECDSA signature bytes");
-                    Error::InvalidChallengeSolution
-                })?;
-                vk.verify(&formatted, &sig).is_ok()
-            }
-            AuthPublicKey::Rsa(pk) => {
-                use rsa::signature::Verifier as _;
-                let verifying_key = rsa::pss::VerifyingKey::<sha2::Sha256>::new(pk.clone());
-                let sig = rsa::pss::Signature::try_from(solution.as_slice()).map_err(|_| {
-                    error!(?solution, "Invalid RSA signature bytes");
-                    Error::InvalidChallengeSolution
-                })?;
-                verifying_key.verify(&formatted, &sig).is_ok()
-            }
-        };
+        let valid = key.verify(*challenge_nonce, USERAGENT_CONTEXT, &signature);

        match valid {
            true => {
@@ -264,93 +316,3 @@ where
        }
    }
 }
-
-impl<T> AuthContext<'_, T>
-where
-    T: Bi<super::Inbound, Result<super::Outbound, Error>> + Send,
-{
-    async fn try_sign_pubkey_integrity_tag(
-        &self,
-        pubkey: &AuthPublicKey,
-    ) -> Result<Option<Vec<u8>>, Error> {
-        let signed = self
-            .conn
-            .actors
-            .key_holder
-            .ask(SignIntegrityTag {
-                purpose_tag: USERAGENT_INTEGRITY_TAG.to_vec(),
-                data_parts: vec![
-                    (pubkey.key_type() as i32).to_be_bytes().to_vec(),
-                    pubkey.to_stored_bytes(),
-                ],
-            })
-            .await;
-
-        match signed {
-            Ok(tag) => Ok(Some(tag)),
-            Err(SendError::HandlerError(keyholder::Error::NotBootstrapped)) => Ok(None),
-            Err(SendError::HandlerError(err)) => {
-                error!(
-                    ?err,
-                    "Keyholder failed to sign user-agent pubkey integrity tag"
-                );
-                Err(Error::internal(
-                    "Keyholder failed to sign user-agent pubkey integrity tag",
-                ))
-            }
-            Err(err) => {
-                error!(
-                    ?err,
-                    "Failed to contact keyholder for user-agent pubkey integrity tag"
-                );
-                Err(Error::internal(
-                    "Failed to contact keyholder for user-agent pubkey integrity tag",
-                ))
-            }
-        }
-    }
-
-    async fn verify_pubkey_attestation_status(
-        &self,
-        pubkey: &AuthPublicKey,
-    ) -> Result<AttestationStatus, Error> {
-        let stored_tag: Option<Option<Vec<u8>>> = {
-            let mut conn = self.conn.db.get().await.map_err(|e| {
-                error!(error = ?e, "Database pool error");
-                Error::internal("Database unavailable")
-            })?;
-
-            schema::useragent_client::table
-                .filter(schema::useragent_client::public_key.eq(pubkey.to_stored_bytes()))
-                .filter(schema::useragent_client::key_type.eq(pubkey.key_type()))
-                .select(schema::useragent_client::pubkey_integrity_tag)
-                .first::<Option<Vec<u8>>>(&mut conn)
-                .await
-                .optional()
-                .map_err(|e| {
-                    error!(error = ?e, "Database error");
-                    Error::internal("Database operation failed")
-                })?
-        };
-
-        let Some(stored_tag) = stored_tag else {
-            return Err(Error::UnregisteredPublicKey);
-        };
-
-        let Some(expected_tag) = self.try_sign_pubkey_integrity_tag(pubkey).await? else {
-            return Ok(AttestationStatus::Unavailable);
-        };
-
-        match stored_tag {
-            Some(stored_tag) if stored_tag == expected_tag => Ok(AttestationStatus::Attested),
-            Some(_) => {
-                error!("User-agent pubkey integrity tag mismatch");
-                Ok(AttestationStatus::NotAttested)
-            }
-            None => {
-                error!("Missing pubkey integrity tag for registered key while vault is unsealed");
-                Ok(AttestationStatus::NotAttested)
-            }
-        }
-    }
-}
--- a/server/crates/arbiter-server/src/actors/user_agent/mod.rs
+++ b/server/crates/arbiter-server/src/actors/user_agent/mod.rs
@@ -1,79 +1,25 @@
 use crate::{
    actors::{GlobalActors, client::ClientProfile},
-    db::{self, models::KeyType},
+    crypto::integrity::Integrable,
+    db,
 };
+use arbiter_crypto::authn;

-/// Abstraction over Ed25519 / ECDSA-secp256k1 / RSA public keys used during the auth handshake.
-#[derive(Clone, Debug)]
-pub enum AuthPublicKey {
-    Ed25519(ed25519_dalek::VerifyingKey),
-    /// Compressed SEC1 public key; signature bytes are raw 64-byte (r||s).
-    EcdsaSecp256k1(k256::ecdsa::VerifyingKey),
-    /// RSA-2048+ public key (Windows Hello / KeyCredentialManager); signature bytes are PSS+SHA-256.
-    Rsa(rsa::RsaPublicKey),
+#[derive(Debug, arbiter_macros::Hashable)]
+pub struct UserAgentCredentials {
+    pub pubkey: authn::PublicKey,
+    pub nonce: i32,
 }

-impl AuthPublicKey {
-    /// Canonical bytes stored in DB and echoed back in the challenge.
-    /// Ed25519: raw 32 bytes. ECDSA: SEC1 compressed 33 bytes. RSA: DER-encoded SPKI.
-    pub fn to_stored_bytes(&self) -> Vec<u8> {
-        match self {
-            AuthPublicKey::Ed25519(k) => k.to_bytes().to_vec(),
-            // SEC1 compressed (33 bytes) is the natural compact format for secp256k1
-            AuthPublicKey::EcdsaSecp256k1(k) => k.to_encoded_point(true).as_bytes().to_vec(),
-            AuthPublicKey::Rsa(k) => {
-                use rsa::pkcs8::EncodePublicKey as _;
-                #[allow(clippy::expect_used)]
-                k.to_public_key_der()
-                    .expect("rsa SPKI encoding is infallible")
-                    .to_vec()
-            }
-        }
-    }
-
-    pub fn key_type(&self) -> KeyType {
-        match self {
-            AuthPublicKey::Ed25519(_) => KeyType::Ed25519,
-            AuthPublicKey::EcdsaSecp256k1(_) => KeyType::EcdsaSecp256k1,
-            AuthPublicKey::Rsa(_) => KeyType::Rsa,
-        }
-    }
-}
-
-impl TryFrom<(KeyType, Vec<u8>)> for AuthPublicKey {
-    type Error = &'static str;
-
-    fn try_from(value: (KeyType, Vec<u8>)) -> Result<Self, Self::Error> {
-        let (key_type, bytes) = value;
-        match key_type {
-            KeyType::Ed25519 => {
-                let bytes: [u8; 32] = bytes.try_into().map_err(|_| "invalid Ed25519 key length")?;
-                let key = ed25519_dalek::VerifyingKey::from_bytes(&bytes)
-                    .map_err(|_e| "invalid Ed25519 key")?;
-                Ok(AuthPublicKey::Ed25519(key))
-            }
-            KeyType::EcdsaSecp256k1 => {
-                let point =
-                    k256::EncodedPoint::from_bytes(&bytes).map_err(|_e| "invalid ECDSA key")?;
-                let key = k256::ecdsa::VerifyingKey::from_encoded_point(&point)
-                    .map_err(|_e| "invalid ECDSA key")?;
-                Ok(AuthPublicKey::EcdsaSecp256k1(key))
-            }
-            KeyType::Rsa => {
-                use rsa::pkcs8::DecodePublicKey as _;
-                let key = rsa::RsaPublicKey::from_public_key_der(&bytes)
-                    .map_err(|_e| "invalid RSA key")?;
-                Ok(AuthPublicKey::Rsa(key))
-            }
-        }
-    }
+impl Integrable for UserAgentCredentials {
+    const KIND: &'static str = "useragent_credentials";
 }

 // Messages, sent by user agent to connection client without having a request
 #[derive(Debug)]
 pub enum OutOfBand {
    ClientConnectionRequest { profile: ClientProfile },
-    ClientConnectionCancel { pubkey: ed25519_dalek::VerifyingKey },
+    ClientConnectionCancel { pubkey: authn::PublicKey },
 }

 pub struct UserAgentConnection {
--- a/server/crates/arbiter-server/src/actors/user_agent/session.rs
+++ b/server/crates/arbiter-server/src/actors/user_agent/session.rs
@@ -1,8 +1,9 @@
+use arbiter_crypto::authn;
+
 use std::{borrow::Cow, collections::HashMap};

 use arbiter_proto::transport::Sender;
 use async_trait::async_trait;
-use ed25519_dalek::VerifyingKey;
 use kameo::{Actor, actor::ActorRef, messages};
 use thiserror::Error;
 use tracing::error;
@@ -12,7 +13,6 @@ use crate::actors::{
    flow_coordinator::{RegisterUserAgent, client_connect_approval::ClientApprovalController},
    user_agent::{OutOfBand, UserAgentConnection},
 };
-
 mod state;
 use state::{DummyContext, UserAgentEvents, UserAgentStateMachine};

@@ -47,6 +47,7 @@ impl Error {
 }

 pub struct PendingClientApproval {
+    pubkey: authn::PublicKey,
    controller: ActorRef<ClientApprovalController>,
 }

@@ -55,7 +56,7 @@ pub struct UserAgentSession {
    state: UserAgentStateMachine<DummyContext>,
    sender: Box<dyn Sender<OutOfBand>>,

-    pending_client_approvals: HashMap<VerifyingKey, PendingClientApproval>,
+    pending_client_approvals: HashMap<Vec<u8>, PendingClientApproval>,
 }

 pub mod connection;
@@ -118,8 +119,13 @@ impl UserAgentSession {
            return;
        }

-        self.pending_client_approvals
-            .insert(client.pubkey, PendingClientApproval { controller });
+        self.pending_client_approvals.insert(
+            client.pubkey.to_bytes(),
+            PendingClientApproval {
+                pubkey: client.pubkey,
+                controller,
+            },
+        );
    }
 }

@@ -158,14 +164,18 @@ impl Actor for UserAgentSession {
        let cancelled_pubkey = self
            .pending_client_approvals
            .iter()
-            .find_map(|(k, v)| (v.controller.id() == id).then_some(*k));
+            .find_map(|(k, v)| (v.controller.id() == id).then_some(k.clone()));

-        if let Some(pubkey) = cancelled_pubkey {
-            self.pending_client_approvals.remove(&pubkey);
+        if let Some(pubkey_bytes) = cancelled_pubkey {
+            let Some(approval) = self.pending_client_approvals.remove(&pubkey_bytes) else {
+                return Ok(std::ops::ControlFlow::Continue(()));
+            };

            if let Err(e) = self
                .sender
-                .send(OutOfBand::ClientConnectionCancel { pubkey })
+                .send(OutOfBand::ClientConnectionCancel {
+                    pubkey: approval.pubkey,
+                })
                .await
            {
                error!(
--- a/server/crates/arbiter-server/src/actors/user_agent/session/connection.rs
+++ b/server/crates/arbiter-server/src/actors/user_agent/session/connection.rs
@@ -1,6 +1,10 @@
 use std::sync::Mutex;

 use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
+use arbiter_crypto::{
+    authn,
+    safecell::{SafeCell, SafeCellHandle as _},
+};
 use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
 use diesel::{ExpressionMethods as _, QueryDsl as _, SelectableHelper};
 use diesel_async::{AsyncConnection, RunQueryDsl};
@@ -13,25 +17,21 @@ use x25519_dalek::{EphemeralSecret, PublicKey};
 use crate::actors::flow_coordinator::client_connect_approval::ClientApprovalAnswer;
 use crate::actors::keyholder::KeyHolderState;
 use crate::actors::user_agent::session::Error;
-use crate::db::models::{
-    EvmWalletAccess, NewEvmWalletAccess, ProgramClient, ProgramClientMetadata,
-};
-use crate::evm::policies::{Grant, SpecificGrant};
-use crate::safe_cell::SafeCell;
-use crate::{
-    actors::{
+use crate::actors::{
    evm::{
        ClientSignTransaction, Generate, ListWallets, SignTransactionError as EvmSignError,
-            UseragentCreateGrant, UseragentDeleteGrant, UseragentListGrants,
+        UseragentCreateGrant, UseragentListGrants,
    },
    keyholder::{self, Bootstrap, TryUnseal},
    user_agent::session::{
        UserAgentSession,
        state::{UnsealContext, UserAgentEvents, UserAgentStates},
    },
-    },
-    safe_cell::SafeCellHandle as _,
 };
+use crate::db::models::{
+    EvmWalletAccess, NewEvmWalletAccess, ProgramClient, ProgramClientMetadata,
+};
+use crate::evm::policies::{Grant, SpecificGrant};

 impl UserAgentSession {
    fn take_unseal_secret(&mut self) -> Result<(EphemeralSecret, PublicKey), Error> {
@@ -120,6 +120,15 @@ pub enum SignTransactionError {
    Internal,
 }

+#[derive(Debug, Error)]
+pub enum GrantMutationError {
+    #[error("Vault is sealed")]
+    VaultSealed,
+
+    #[error("Internal grant mutation error")]
+    Internal,
+}
+
 #[messages]
 impl UserAgentSession {
    #[message]
@@ -331,7 +340,7 @@ impl UserAgentSession {
        &mut self,
        basic: crate::evm::policies::SharedGrantSettings,
        grant: crate::evm::policies::SpecificGrant,
-    ) -> Result<i32, Error> {
+    ) -> Result<i32, GrantMutationError> {
        match self
            .props
            .actors
@@ -342,26 +351,31 @@ impl UserAgentSession {
            Ok(grant_id) => Ok(grant_id),
            Err(err) => {
                error!(?err, "EVM grant create failed");
-                Err(Error::internal("Failed to create EVM grant"))
+                Err(GrantMutationError::Internal)
            }
        }
    }

    #[message]
-    pub(crate) async fn handle_grant_delete(&mut self, grant_id: i32) -> Result<(), Error> {
-        match self
-            .props
-            .actors
-            .evm
-            .ask(UseragentDeleteGrant { grant_id })
-            .await
-        {
-            Ok(()) => Ok(()),
-            Err(err) => {
-                error!(?err, "EVM grant delete failed");
-                Err(Error::internal("Failed to delete EVM grant"))
-            }
-        }
+    pub(crate) async fn handle_grant_delete(
+        &mut self,
+        grant_id: i32,
+    ) -> Result<(), GrantMutationError> {
+        // match self
+        //     .props
+        //     .actors
+        //     .evm
+        //     .ask(UseragentDeleteGrant { grant_id })
+        //     .await
+        // {
+        //     Ok(()) => Ok(()),
+        //     Err(err) => {
+        //         error!(?err, "EVM grant delete failed");
+        //         Err(GrantMutationError::Internal)
+        //     }
+        // }
+       let _ = grant_id;
+        todo!()
    }

    #[message]
@@ -461,10 +475,10 @@ impl UserAgentSession {
    pub(crate) async fn handle_new_client_approve(
        &mut self,
        approved: bool,
-        pubkey: ed25519_dalek::VerifyingKey,
+        pubkey: authn::PublicKey,
        ctx: &mut Context<Self, Result<(), Error>>,
    ) -> Result<(), Error> {
-        let pending_approval = match self.pending_client_approvals.remove(&pubkey) {
+        let pending_approval = match self.pending_client_approvals.remove(&pubkey.to_bytes()) {
            Some(approval) => approval,
            None => {
                error!("Received client connection response for unknown client");
--- a/server/crates/arbiter-server/src/crypto/encryption/mod.rs
+++ b/server/crates/arbiter-server/src/crypto/encryption/mod.rs
@@ -1 +1,3 @@
 pub mod v1;
+
+pub use v1::*;
--- a/server/crates/arbiter-server/src/crypto/encryption/v1.rs
+++ b/server/crates/arbiter-server/src/crypto/encryption/v1.rs
@@ -59,10 +59,8 @@ mod tests {
    use std::ops::Deref as _;

    use super::*;
-    use crate::{
-        crypto::derive_key,
-        safe_cell::{SafeCell, SafeCellHandle as _},
-    };
+    use crate::crypto::derive_key;
+    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

    #[test]
    pub fn derive_seal_key_deterministic() {
--- a/server/crates/arbiter-server/src/crypto/integrity/mod.rs
+++ b/server/crates/arbiter-server/src/crypto/integrity/mod.rs
@@ -1 +1,3 @@
 pub mod v1;
+
+pub use v1::*;
--- a/server/crates/arbiter-server/src/crypto/integrity/v1.rs
+++ b/server/crates/arbiter-server/src/crypto/integrity/v1.rs
@@ -1,78 +1,321 @@
-use crate::{crypto::KeyCell, safe_cell::SafeCellHandle as _};
-use chacha20poly1305::Key;
-use hmac::Mac as _;
+use crate::actors::keyholder;
+use arbiter_crypto::hashing::Hashable;
+use hmac::Hmac;
+use sha2::Sha256;

-pub const USERAGENT_INTEGRITY_DERIVE_TAG: &[u8] = "arbiter/useragent/integrity-key/v1".as_bytes();
-pub const USERAGENT_INTEGRITY_TAG: &[u8] = "arbiter/useragent/pubkey-entry/v1".as_bytes();
+use diesel::{ExpressionMethods as _, QueryDsl, dsl::insert_into, sqlite::Sqlite};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use kameo::{actor::ActorRef, error::SendError};
+use sha2::Digest as _;

-/// Computes an integrity tag for a specific domain and payload shape.
-pub fn compute_integrity_tag<'a, I>(
-    integrity_key: &mut KeyCell,
-    purpose_tag: &[u8],
-    data_parts: I,
-) -> [u8; 32]
-where
-    I: IntoIterator<Item = &'a [u8]>,
-{
-    type HmacSha256 = hmac::Hmac<sha2::Sha256>;
+use crate::{
+    actors::keyholder::{KeyHolder, SignIntegrity, VerifyIntegrity},
+    db::{
+        self,
+        models::{IntegrityEnvelope, NewIntegrityEnvelope},
+        schema::integrity_envelope,
+    },
+};

-    let mut output_tag = [0u8; 32];
-    integrity_key.0.read_inline(|integrity_key_bytes: &Key| {
-        let mut mac = <HmacSha256 as hmac::Mac>::new_from_slice(integrity_key_bytes.as_ref())
-            .expect("HMAC key initialization must not fail for 32-byte key");
-        mac.update(purpose_tag);
-        for data_part in data_parts {
-            mac.update(data_part);
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("Database error: {0}")]
+    Database(#[from] db::DatabaseError),
+
+    #[error("KeyHolder error: {0}")]
+    Keyholder(#[from] keyholder::Error),
+
+    #[error("KeyHolder mailbox error")]
+    KeyholderSend,
+
+    #[error("Integrity envelope is missing for entity {entity_kind}")]
+    MissingEnvelope { entity_kind: &'static str },
+
+    #[error(
+        "Integrity payload version mismatch for entity {entity_kind}: expected {expected}, found {found}"
+    )]
+    PayloadVersionMismatch {
+        entity_kind: &'static str,
+        expected: i32,
+        found: i32,
+    },
+
+    #[error("Integrity MAC mismatch for entity {entity_kind}")]
+    MacMismatch { entity_kind: &'static str },
 }
-        output_tag.copy_from_slice(&mac.finalize().into_bytes());
-    });

-    output_tag
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum AttestationStatus {
+    Attested,
+    Unavailable,
+}
+
+pub const CURRENT_PAYLOAD_VERSION: i32 = 1;
+pub const INTEGRITY_SUBKEY_TAG: &[u8] = b"arbiter/db-integrity-key/v1";
+
+pub type HmacSha256 = Hmac<Sha256>;
+
+pub trait Integrable: Hashable {
+    const KIND: &'static str;
+    const VERSION: i32 = 1;
+}
+
+fn payload_hash(payload: &impl Hashable) -> [u8; 32] {
+    let mut hasher = Sha256::new();
+    payload.hash(&mut hasher);
+    hasher.finalize().into()
+}
+
+fn push_len_prefixed(out: &mut Vec<u8>, bytes: &[u8]) {
+    out.extend_from_slice(&(bytes.len() as u32).to_be_bytes());
+    out.extend_from_slice(bytes);
+}
+
+fn build_mac_input(
+    entity_kind: &str,
+    entity_id: &[u8],
+    payload_version: i32,
+    payload_hash: &[u8; 32],
+) -> Vec<u8> {
+    let mut out = Vec::with_capacity(8 + entity_kind.len() + entity_id.len() + 32);
+    push_len_prefixed(&mut out, entity_kind.as_bytes());
+    push_len_prefixed(&mut out, entity_id);
+    out.extend_from_slice(&payload_version.to_be_bytes());
+    out.extend_from_slice(payload_hash);
+    out
+}
+
+pub trait IntoId {
+    fn into_id(self) -> Vec<u8>;
+}
+
+impl IntoId for i32 {
+    fn into_id(self) -> Vec<u8> {
+        self.to_be_bytes().to_vec()
+    }
+}
+
+impl IntoId for &'_ [u8] {
+    fn into_id(self) -> Vec<u8> {
+        self.to_vec()
+    }
+}
+
+pub async fn sign_entity<E: Integrable>(
+    conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    keyholder: &ActorRef<KeyHolder>,
+    entity: &E,
+    entity_id: impl IntoId,
+) -> Result<(), Error> {
+    let payload_hash = payload_hash(&entity);
+
+    let entity_id = entity_id.into_id();
+
+    let mac_input = build_mac_input(E::KIND, &entity_id, E::VERSION, &payload_hash);
+
+    let (key_version, mac) = keyholder
+        .ask(SignIntegrity { mac_input })
+        .await
+        .map_err(|err| match err {
+            kameo::error::SendError::HandlerError(inner) => Error::Keyholder(inner),
+            _ => Error::KeyholderSend,
+        })?;
+
+    insert_into(integrity_envelope::table)
+        .values(NewIntegrityEnvelope {
+            entity_kind: E::KIND.to_owned(),
+            entity_id,
+            payload_version: E::VERSION,
+            key_version,
+            mac: mac.to_vec(),
+        })
+        .on_conflict((
+            integrity_envelope::entity_id,
+            integrity_envelope::entity_kind,
+        ))
+        .do_update()
+        .set((
+            integrity_envelope::payload_version.eq(E::VERSION),
+            integrity_envelope::key_version.eq(key_version),
+            integrity_envelope::mac.eq(mac),
+        ))
+        .execute(conn)
+        .await
+        .map_err(db::DatabaseError::from)?;
+
+    Ok(())
+}
+
+pub async fn verify_entity<E: Integrable>(
+    conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    keyholder: &ActorRef<KeyHolder>,
+    entity: &E,
+    entity_id: impl IntoId,
+) -> Result<AttestationStatus, Error> {
+    let entity_id = entity_id.into_id();
+    let envelope: IntegrityEnvelope = integrity_envelope::table
+        .filter(integrity_envelope::entity_kind.eq(E::KIND))
+        .filter(integrity_envelope::entity_id.eq(&entity_id))
+        .first(conn)
+        .await
+        .map_err(|err| match err {
+            diesel::result::Error::NotFound => Error::MissingEnvelope {
+                entity_kind: E::KIND,
+            },
+            other => Error::Database(db::DatabaseError::from(other)),
+        })?;
+
+    if envelope.payload_version != E::VERSION {
+        return Err(Error::PayloadVersionMismatch {
+            entity_kind: E::KIND,
+            expected: E::VERSION,
+            found: envelope.payload_version,
+        });
+    }
+
+    let payload_hash = payload_hash(&entity);
+    let mac_input = build_mac_input(E::KIND, &entity_id, envelope.payload_version, &payload_hash);
+
+    let result = keyholder
+        .ask(VerifyIntegrity {
+            mac_input,
+            expected_mac: envelope.mac,
+            key_version: envelope.key_version,
+        })
+        .await;
+
+    match result {
+        Ok(true) => Ok(AttestationStatus::Attested),
+        Ok(false) => Err(Error::MacMismatch {
+            entity_kind: E::KIND,
+        }),
+        Err(SendError::HandlerError(keyholder::Error::NotBootstrapped)) => {
+            Ok(AttestationStatus::Unavailable)
+        }
+        Err(_) => Err(Error::KeyholderSend),
+    }
 }

 #[cfg(test)]
 mod tests {
+    use diesel::{ExpressionMethods as _, QueryDsl};
+    use diesel_async::RunQueryDsl;
+    use kameo::{actor::ActorRef, prelude::Spawn};
+
    use crate::{
-        crypto::{derive_key, encryption::v1::generate_salt},
-        safe_cell::{SafeCell, SafeCellHandle as _},
+        actors::keyholder::{Bootstrap, KeyHolder},
+        db::{self, schema},
+    };
+    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+
+    use super::{Error, Integrable, sign_entity, verify_entity};
+    #[derive(Clone, arbiter_macros::Hashable)]
+    struct DummyEntity {
+        payload_version: i32,
+        payload: Vec<u8>,
+    }
+    impl Integrable for DummyEntity {
+        const KIND: &'static str = "dummy_entity";
+    }
+
+    async fn bootstrapped_keyholder(db: &db::DatabasePool) -> ActorRef<KeyHolder> {
+        let actor = KeyHolder::spawn(KeyHolder::new(db.clone()).await.unwrap());
+        actor
+            .ask(Bootstrap {
+                seal_key_raw: SafeCell::new(b"integrity-test-seal-key".to_vec()),
+            })
+            .await
+            .unwrap();
+        actor
+    }
+
+    #[tokio::test]
+    async fn sign_writes_envelope_and_verify_passes() {
+        let db = db::create_test_pool().await;
+        let keyholder = bootstrapped_keyholder(&db).await;
+        let mut conn = db.get().await.unwrap();
+
+        const ENTITY_ID: &[u8] = b"entity-id-7";
+
+        let entity = DummyEntity {
+            payload_version: 1,
+            payload: b"payload-v1".to_vec(),
        };

-    use super::{USERAGENT_INTEGRITY_TAG, compute_integrity_tag};
+        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+            .await
+            .unwrap();

-    #[test]
-    pub fn integrity_tag_deterministic() {
-        let salt = generate_salt();
-        let mut integrity_key = derive_key(SafeCell::new(b"password".to_vec()), &salt);
-        let key_type = 1i32.to_be_bytes();
-        let t1 = compute_integrity_tag(
-            &mut integrity_key,
-            USERAGENT_INTEGRITY_TAG,
-            [key_type.as_slice(), b"pubkey".as_ref()],
-        );
-        let t2 = compute_integrity_tag(
-            &mut integrity_key,
-            USERAGENT_INTEGRITY_TAG,
-            [key_type.as_slice(), b"pubkey".as_ref()],
-        );
-        assert_eq!(t1, t2);
+        let count: i64 = schema::integrity_envelope::table
+            .filter(schema::integrity_envelope::entity_kind.eq("dummy_entity"))
+            .filter(schema::integrity_envelope::entity_id.eq(ENTITY_ID))
+            .count()
+            .get_result(&mut conn)
+            .await
+            .unwrap();
+
+        assert_eq!(count, 1, "envelope row must be created exactly once");
+        verify_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+            .await
+            .unwrap();
    }

-    #[test]
-    pub fn integrity_tag_changes_with_payload() {
-        let salt = generate_salt();
-        let mut integrity_key = derive_key(SafeCell::new(b"password".to_vec()), &salt);
-        let key_type_1 = 1i32.to_be_bytes();
-        let key_type_2 = 2i32.to_be_bytes();
-        let t1 = compute_integrity_tag(
-            &mut integrity_key,
-            USERAGENT_INTEGRITY_TAG,
-            [key_type_1.as_slice(), b"pubkey".as_ref()],
-        );
-        let t2 = compute_integrity_tag(
-            &mut integrity_key,
-            USERAGENT_INTEGRITY_TAG,
-            [key_type_2.as_slice(), b"pubkey".as_ref()],
-        );
-        assert_ne!(t1, t2);
+    #[tokio::test]
+    async fn tampered_mac_fails_verification() {
+        let db = db::create_test_pool().await;
+        let keyholder = bootstrapped_keyholder(&db).await;
+        let mut conn = db.get().await.unwrap();
+
+        const ENTITY_ID: &[u8] = b"entity-id-11";
+
+        let entity = DummyEntity {
+            payload_version: 1,
+            payload: b"payload-v1".to_vec(),
+        };
+
+        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+            .await
+            .unwrap();
+
+        diesel::update(schema::integrity_envelope::table)
+            .filter(schema::integrity_envelope::entity_kind.eq("dummy_entity"))
+            .filter(schema::integrity_envelope::entity_id.eq(ENTITY_ID))
+            .set(schema::integrity_envelope::mac.eq(vec![0u8; 32]))
+            .execute(&mut conn)
+            .await
+            .unwrap();
+
+        let err = verify_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+            .await
+            .unwrap_err();
+        assert!(matches!(err, Error::MacMismatch { .. }));
+    }
+
+    #[tokio::test]
+    async fn changed_payload_fails_verification() {
+        let db = db::create_test_pool().await;
+        let keyholder = bootstrapped_keyholder(&db).await;
+        let mut conn = db.get().await.unwrap();
+
+        const ENTITY_ID: &[u8] = b"entity-id-21";
+
+        let entity = DummyEntity {
+            payload_version: 1,
+            payload: b"payload-v1".to_vec(),
+        };
+
+        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+            .await
+            .unwrap();
+
+        let tampered = DummyEntity {
+            payload: b"payload-v1-but-tampered".to_vec(),
+            ..entity
+        };
+
+        let err = verify_entity(&mut conn, &keyholder, &tampered, ENTITY_ID)
+            .await
+            .unwrap_err();
+        assert!(matches!(err, Error::MacMismatch { .. }));
    }
 }
--- a/server/crates/arbiter-server/src/crypto/mod.rs
+++ b/server/crates/arbiter-server/src/crypto/mod.rs
@@ -10,7 +10,7 @@ use rand::{
    rngs::{StdRng, SysRng},
 };

-use crate::safe_cell::{SafeCell, SafeCellHandle as _};
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

 pub mod encryption;
 pub mod integrity;
@@ -102,11 +102,21 @@ impl KeyCell {
    }
 }

-/// User password might be of different length, have not enough entropy, etc...
 /// Derive a fixed-length key from the password using Argon2id, which is designed for password hashing and key derivation.
 pub fn derive_key(mut password: SafeCell<Vec<u8>>, salt: &Salt) -> KeyCell {
+    let params = {
+        #[cfg(debug_assertions)]
+        {
+            argon2::Params::new(8, 1, 1, None).unwrap()
+        }
+
+        #[cfg(not(debug_assertions))]
+        {
+            argon2::Params::new(262_144, 3, 4, None).unwrap()
+        }
+    };
+
    #[allow(clippy::unwrap_used)]
-    let params = argon2::Params::new(262_144, 3, 4, None).unwrap();
    let hasher = Argon2::new(Algorithm::Argon2id, argon2::Version::V0x13, params);
    let mut key = SafeCell::new(Key::default());
    password.read_inline(|password_source| {
@@ -131,7 +141,7 @@ mod tests {
        derive_key,
        encryption::v1::{Nonce, generate_salt},
    };
-    use crate::safe_cell::{SafeCell, SafeCellHandle as _};
+    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

    #[test]
    pub fn encrypt_decrypt() {
--- a/server/crates/arbiter-server/src/db/mod.rs
+++ b/server/crates/arbiter-server/src/db/mod.rs
@@ -133,6 +133,7 @@ pub async fn create_pool(url: Option<&str>) -> Result<DatabasePool, DatabaseSetu
    Ok(pool)
 }

+#[mutants::skip]
 pub async fn create_test_pool() -> DatabasePool {
    use rand::distr::{Alphanumeric, SampleString as _};

--- a/server/crates/arbiter-server/src/db/models.rs
+++ b/server/crates/arbiter-server/src/db/models.rs
@@ -5,7 +5,7 @@ use crate::db::schema::{
    self, aead_encrypted, arbiter_settings, evm_basic_grant, evm_ether_transfer_grant,
    evm_ether_transfer_grant_target, evm_ether_transfer_limit, evm_token_transfer_grant,
    evm_token_transfer_log, evm_token_transfer_volume_limit, evm_transaction_log, evm_wallet,
-    root_key_history, tls_history,
+    integrity_envelope, root_key_history, tls_history,
 };
 use chrono::{DateTime, Utc};
 use diesel::{prelude::*, sqlite::Sqlite};
@@ -72,40 +72,6 @@ pub mod types {
            Ok(SqliteTimestamp(datetime))
        }
    }
-
-    /// Key algorithm stored in the `useragent_client.key_type` column.
-    /// Values must stay stable — they are persisted in the database.
-    #[derive(Debug, Clone, Copy, PartialEq, Eq, FromSqlRow, AsExpression, strum::FromRepr)]
-    #[diesel(sql_type = Integer)]
-    #[repr(i32)]
-    pub enum KeyType {
-        Ed25519 = 1,
-        EcdsaSecp256k1 = 2,
-        Rsa = 3,
-    }
-
-    impl ToSql<Integer, Sqlite> for KeyType {
-        fn to_sql<'b>(
-            &'b self,
-            out: &mut diesel::serialize::Output<'b, '_, Sqlite>,
-        ) -> diesel::serialize::Result {
-            out.set_value(*self as i32);
-            Ok(IsNull::No)
-        }
-    }
-
-    impl FromSql<Integer, Sqlite> for KeyType {
-        fn from_sql(
-            mut bytes: <Sqlite as diesel::backend::Backend>::RawValue<'_>,
-        ) -> diesel::deserialize::Result<Self> {
-            let Some(SqliteType::Long) = bytes.value_type() else {
-                return Err("Expected Integer for KeyType".into());
-            };
-            let discriminant = bytes.read_long();
-            KeyType::from_repr(discriminant as i32)
-                .ok_or_else(|| format!("Unknown KeyType discriminant: {discriminant}").into())
-        }
-    }
 }
 pub use types::*;

@@ -242,10 +208,8 @@ pub struct UseragentClient {
    pub id: i32,
    pub nonce: i32,
    pub public_key: Vec<u8>,
-    pub pubkey_integrity_tag: Option<Vec<u8>>,
    pub created_at: SqliteTimestamp,
    pub updated_at: SqliteTimestamp,
-    pub key_type: KeyType,
 }

 #[derive(Models, Queryable, Debug, Insertable, Selectable)]
@@ -377,3 +341,22 @@ pub struct EvmTokenTransferLog {
    pub value: Vec<u8>,
    pub created_at: SqliteTimestamp,
 }
+
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = integrity_envelope, check_for_backend(Sqlite))]
+#[view(
+    NewIntegrityEnvelope,
+    derive(Insertable),
+    omit(id, signed_at, created_at),
+    attributes_with = "deriveless"
+)]
+pub struct IntegrityEnvelope {
+    pub id: i32,
+    pub entity_kind: String,
+    pub entity_id: Vec<u8>,
+    pub payload_version: i32,
+    pub key_version: i32,
+    pub mac: Vec<u8>,
+    pub signed_at: SqliteTimestamp,
+    pub created_at: SqliteTimestamp,
+}
--- a/server/crates/arbiter-server/src/db/schema.rs
+++ b/server/crates/arbiter-server/src/db/schema.rs
@@ -139,6 +139,19 @@ diesel::table! {
    }
 }

+diesel::table! {
+    integrity_envelope (id) {
+        id -> Integer,
+        entity_kind -> Text,
+        entity_id -> Binary,
+        payload_version -> Integer,
+        key_version -> Integer,
+        mac -> Binary,
+        signed_at -> Integer,
+        created_at -> Integer,
+    }
+}
+
 diesel::table! {
    program_client (id) {
        id -> Integer,
@@ -178,7 +191,6 @@ diesel::table! {
        id -> Integer,
        nonce -> Integer,
        public_key -> Binary,
-        pubkey_integrity_tag -> Nullable<Binary>,
        key_type -> Integer,
        created_at -> Integer,
        updated_at -> Integer,
@@ -220,6 +232,7 @@ diesel::allow_tables_to_appear_in_same_query!(
    evm_transaction_log,
    evm_wallet,
    evm_wallet_access,
+    integrity_envelope,
    program_client,
    root_key_history,
    tls_history,
--- a/server/crates/arbiter-server/src/evm/mod.rs
+++ b/server/crates/arbiter-server/src/evm/mod.rs
@@ -8,8 +8,11 @@ use alloy::{
 use chrono::Utc;
 use diesel::{ExpressionMethods as _, QueryDsl as _, QueryResult, insert_into, sqlite::Sqlite};
 use diesel_async::{AsyncConnection, RunQueryDsl};
+use kameo::actor::ActorRef;

 use crate::{
+    actors::keyholder::KeyHolder,
+    crypto::integrity,
    db::{
        self, DatabaseError,
        models::{
@@ -18,8 +21,8 @@ use crate::{
        schema::{self, evm_transaction_log},
    },
    evm::policies::{
-        DatabaseID, EvalContext, EvalViolation, FullGrant, Grant, Policy, SharedGrantSettings,
-        SpecificGrant, SpecificMeaning, ether_transfer::EtherTransfer,
+        CombinedSettings, DatabaseID, EvalContext, EvalViolation, Grant, Policy,
+        SharedGrantSettings, SpecificGrant, SpecificMeaning, ether_transfer::EtherTransfer,
        token_transfers::TokenTransfer,
    },
 };
@@ -36,6 +39,9 @@ pub enum PolicyError {
    Violations(Vec<EvalViolation>),
    #[error("No matching grant found")]
    NoMatchingGrant,
+
+    #[error("Integrity error: {0}")]
+    Integrity(#[from] integrity::Error),
 }

 #[derive(Debug, thiserror::Error)]
@@ -57,6 +63,15 @@ pub enum AnalyzeError {
    UnsupportedTransactionType,
 }

+#[derive(Debug, thiserror::Error)]
+pub enum ListError {
+    #[error("Database error")]
+    Database(#[from] crate::db::DatabaseError),
+
+    #[error("Integrity verification failed for grant")]
+    Integrity(#[from] integrity::Error),
+}
+
 /// Controls whether a transaction should be executed or only validated
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum RunKind {
@@ -75,6 +90,14 @@ async fn check_shared_constraints(
    let mut violations = Vec::new();
    let now = Utc::now();

+    if shared.chain != context.chain {
+        violations.push(EvalViolation::MismatchingChainId {
+            expected: shared.chain,
+            actual: context.chain,
+        });
+        return Ok(violations);
+    }
+
    // Validity window
    if shared.valid_from.is_some_and(|t| now < t) || shared.valid_until.is_some_and(|t| now > t) {
        violations.push(EvalViolation::InvalidTime);
@@ -115,6 +138,7 @@ async fn check_shared_constraints(
 // Supporting only EIP-1559 transactions for now, but we can easily extend this to support legacy transactions if needed
 pub struct Engine {
    db: db::DatabasePool,
+    keyholder: ActorRef<KeyHolder>,
 }

 impl Engine {
@@ -123,7 +147,10 @@ impl Engine {
        context: EvalContext,
        meaning: &P::Meaning,
        run_kind: RunKind,
-    ) -> Result<(), PolicyError> {
+    ) -> Result<(), PolicyError>
+    where
+        P::Settings: Clone,
+    {
        let mut conn = self.db.get().await.map_err(DatabaseError::from)?;

        let grant = P::try_find_grant(&context, &mut conn)
@@ -131,8 +158,14 @@ impl Engine {
            .map_err(DatabaseError::from)?
            .ok_or(PolicyError::NoMatchingGrant)?;

-        let mut violations =
-            check_shared_constraints(&context, &grant.shared, grant.shared_grant_id, &mut conn)
+        integrity::verify_entity(&mut conn, &self.keyholder, &grant.settings, grant.id).await?;
+
+        let mut violations = check_shared_constraints(
+            &context,
+            &grant.settings.shared,
+            grant.common_settings_id,
+            &mut conn,
+        )
        .await
        .map_err(DatabaseError::from)?;
        violations.extend(
@@ -143,12 +176,14 @@ impl Engine {

        if !violations.is_empty() {
            return Err(PolicyError::Violations(violations));
-        } else if run_kind == RunKind::Execution {
+        }
+
+        if run_kind == RunKind::Execution {
            conn.transaction(|conn| {
                Box::pin(async move {
                    let log_id: i32 = insert_into(evm_transaction_log::table)
                        .values(&NewEvmTransactionLog {
-                            grant_id: grant.shared_grant_id,
+                            grant_id: grant.common_settings_id,
                            wallet_access_id: context.target.id,
                            chain_id: context.chain as i32,
                            eth_value: utils::u256_to_bytes(context.value).to_vec(),
@@ -172,15 +207,19 @@ impl Engine {
 }

 impl Engine {
-    pub fn new(db: db::DatabasePool) -> Self {
-        Self { db }
+    pub fn new(db: db::DatabasePool, keyholder: ActorRef<KeyHolder>) -> Self {
+        Self { db, keyholder }
    }

    pub async fn create_grant<P: Policy>(
        &self,
-        full_grant: FullGrant<P::Settings>,
-    ) -> Result<i32, DatabaseError> {
+        full_grant: CombinedSettings<P::Settings>,
+    ) -> Result<i32, DatabaseError>
+    where
+        P::Settings: Clone,
+    {
        let mut conn = self.db.get().await?;
+        let keyholder = self.keyholder.clone();

        let id = conn
            .transaction(|conn| {
@@ -189,25 +228,25 @@ impl Engine {

                    let basic_grant: EvmBasicGrant = insert_into(evm_basic_grant::table)
                        .values(&NewEvmBasicGrant {
-                            chain_id: full_grant.basic.chain as i32,
-                            wallet_access_id: full_grant.basic.wallet_access_id,
-                            valid_from: full_grant.basic.valid_from.map(SqliteTimestamp),
-                            valid_until: full_grant.basic.valid_until.map(SqliteTimestamp),
+                            chain_id: full_grant.shared.chain as i32,
+                            wallet_access_id: full_grant.shared.wallet_access_id,
+                            valid_from: full_grant.shared.valid_from.map(SqliteTimestamp),
+                            valid_until: full_grant.shared.valid_until.map(SqliteTimestamp),
                            max_gas_fee_per_gas: full_grant
-                                .basic
+                                .shared
                                .max_gas_fee_per_gas
                                .map(|fee| utils::u256_to_bytes(fee).to_vec()),
                            max_priority_fee_per_gas: full_grant
-                                .basic
+                                .shared
                                .max_priority_fee_per_gas
                                .map(|fee| utils::u256_to_bytes(fee).to_vec()),
                            rate_limit_count: full_grant
-                                .basic
+                                .shared
                                .rate_limit
                                .as_ref()
                                .map(|rl| rl.count as i32),
                            rate_limit_window_secs: full_grant
-                                .basic
+                                .shared
                                .rate_limit
                                .as_ref()
                                .map(|rl| rl.window.num_seconds() as i32),
@@ -217,7 +256,13 @@ impl Engine {
                        .get_result(conn)
                        .await?;

-                    P::create_grant(&basic_grant, &full_grant.specific, conn).await
+                    P::create_grant(&basic_grant, &full_grant.specific, conn).await?;
+
+                    integrity::sign_entity(conn, &keyholder, &full_grant, basic_grant.id)
+                        .await
+                        .map_err(|_| diesel::result::Error::RollbackTransaction)?;
+
+                    QueryResult::Ok(basic_grant.id)
                })
            })
            .await?;
@@ -225,33 +270,36 @@ impl Engine {
        Ok(id)
    }

-    pub async fn list_all_grants(&self) -> Result<Vec<Grant<SpecificGrant>>, DatabaseError> {
-        let mut conn = self.db.get().await?;
+    async fn list_one_kind<Kind: Policy, Y>(
+        &self,
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> Result<impl Iterator<Item = Grant<Y>>, ListError>
+    where
+        Y: From<Kind::Settings>,
+    {
+        let all_grants = Kind::find_all_grants(conn)
+            .await
+            .map_err(DatabaseError::from)?;
+
+        // Verify integrity of all grants before returning any results
+        for grant in &all_grants {
+            integrity::verify_entity(conn, &self.keyholder, &grant.settings, grant.id).await?;
+        }
+
+        Ok(all_grants.into_iter().map(|g| Grant {
+            id: g.id,
+            common_settings_id: g.common_settings_id,
+            settings: g.settings.generalize(),
+        }))
+    }
+
+    pub async fn list_all_grants(&self) -> Result<Vec<Grant<SpecificGrant>>, ListError> {
+        let mut conn = self.db.get().await.map_err(DatabaseError::from)?;

        let mut grants: Vec<Grant<SpecificGrant>> = Vec::new();

-        grants.extend(
-            EtherTransfer::find_all_grants(&mut conn)
-                .await?
-                .into_iter()
-                .map(|g| Grant {
-                    id: g.id,
-                    shared_grant_id: g.shared_grant_id,
-                    shared: g.shared,
-                    settings: SpecificGrant::EtherTransfer(g.settings),
-                }),
-        );
-        grants.extend(
-            TokenTransfer::find_all_grants(&mut conn)
-                .await?
-                .into_iter()
-                .map(|g| Grant {
-                    id: g.id,
-                    shared_grant_id: g.shared_grant_id,
-                    shared: g.shared,
-                    settings: SpecificGrant::TokenTransfer(g.settings),
-                }),
-        );
+        grants.extend(self.list_one_kind::<EtherTransfer, _>(&mut conn).await?);
+        grants.extend(self.list_one_kind::<TokenTransfer, _>(&mut conn).await?);

        Ok(grants)
    }
@@ -297,3 +345,255 @@ impl Engine {
        Err(VetError::UnsupportedTransactionType)
    }
 }
+
+#[cfg(test)]
+mod tests {
+    use alloy::primitives::{Address, Bytes, U256, address};
+    use chrono::{Duration, Utc};
+    use diesel::{SelectableHelper, insert_into};
+    use diesel_async::RunQueryDsl;
+    use rstest::rstest;
+
+    use crate::db::{
+        self, DatabaseConnection,
+        models::{
+            EvmBasicGrant, EvmWalletAccess, NewEvmBasicGrant, NewEvmTransactionLog, SqliteTimestamp,
+        },
+        schema::{evm_basic_grant, evm_transaction_log},
+    };
+    use crate::evm::policies::{
+        EvalContext, EvalViolation, SharedGrantSettings, TransactionRateLimit,
+    };
+
+    use super::check_shared_constraints;
+
+    const WALLET_ACCESS_ID: i32 = 1;
+    const CHAIN_ID: u64 = 1;
+    const RECIPIENT: Address = address!("1111111111111111111111111111111111111111");
+
+    fn context() -> EvalContext {
+        EvalContext {
+            target: EvmWalletAccess {
+                id: WALLET_ACCESS_ID,
+                wallet_id: 10,
+                client_id: 20,
+                created_at: SqliteTimestamp(Utc::now()),
+            },
+            chain: CHAIN_ID,
+            to: RECIPIENT,
+            value: U256::ZERO,
+            calldata: Bytes::new(),
+            max_fee_per_gas: 100,
+            max_priority_fee_per_gas: 10,
+        }
+    }
+
+    fn shared_settings() -> SharedGrantSettings {
+        SharedGrantSettings {
+            wallet_access_id: WALLET_ACCESS_ID,
+            chain: CHAIN_ID,
+            valid_from: None,
+            valid_until: None,
+            max_gas_fee_per_gas: None,
+            max_priority_fee_per_gas: None,
+            rate_limit: None,
+        }
+    }
+
+    async fn insert_basic_grant(
+        conn: &mut DatabaseConnection,
+        shared: &SharedGrantSettings,
+    ) -> EvmBasicGrant {
+        insert_into(evm_basic_grant::table)
+            .values(NewEvmBasicGrant {
+                wallet_access_id: shared.wallet_access_id,
+                chain_id: shared.chain as i32,
+                valid_from: shared.valid_from.map(SqliteTimestamp),
+                valid_until: shared.valid_until.map(SqliteTimestamp),
+                max_gas_fee_per_gas: shared
+                    .max_gas_fee_per_gas
+                    .map(|fee| super::utils::u256_to_bytes(fee).to_vec()),
+                max_priority_fee_per_gas: shared
+                    .max_priority_fee_per_gas
+                    .map(|fee| super::utils::u256_to_bytes(fee).to_vec()),
+                rate_limit_count: shared.rate_limit.as_ref().map(|limit| limit.count as i32),
+                rate_limit_window_secs: shared
+                    .rate_limit
+                    .as_ref()
+                    .map(|limit| limit.window.num_seconds() as i32),
+                revoked_at: None,
+            })
+            .returning(EvmBasicGrant::as_select())
+            .get_result(conn)
+            .await
+            .unwrap()
+    }
+
+    #[rstest]
+    #[case::matching_chain(CHAIN_ID, false)]
+    #[case::mismatching_chain(CHAIN_ID + 1, true)]
+    #[tokio::test]
+    async fn check_shared_constraints_enforces_chain_id(
+        #[case] context_chain: u64,
+        #[case] expect_mismatch: bool,
+    ) {
+        let db = db::create_test_pool().await;
+        let mut conn = db.get().await.unwrap();
+
+        let context = EvalContext {
+            chain: context_chain,
+            ..context()
+        };
+
+        let violations = check_shared_constraints(&context, &shared_settings(), 999, &mut *conn)
+            .await
+            .unwrap();
+
+        assert_eq!(
+            violations
+                .iter()
+                .any(|violation| matches!(violation, EvalViolation::MismatchingChainId { .. })),
+            expect_mismatch
+        );
+
+        if expect_mismatch {
+            assert_eq!(violations.len(), 1);
+        } else {
+            assert!(violations.is_empty());
+        }
+    }
+
+    #[rstest]
+    #[case::valid_from_in_bounds(Some(Utc::now() - Duration::hours(1)), None, false)]
+    #[case::valid_from_out_of_bounds(Some(Utc::now() + Duration::hours(1)), None, true)]
+    #[case::valid_until_in_bounds(None, Some(Utc::now() + Duration::hours(1)), false)]
+    #[case::valid_until_out_of_bounds(None, Some(Utc::now() - Duration::hours(1)), true)]
+    #[tokio::test]
+    async fn check_shared_constraints_enforces_validity_window(
+        #[case] valid_from: Option<chrono::DateTime<Utc>>,
+        #[case] valid_until: Option<chrono::DateTime<Utc>>,
+        #[case] expect_invalid_time: bool,
+    ) {
+        let db = db::create_test_pool().await;
+        let mut conn = db.get().await.unwrap();
+
+        let shared = SharedGrantSettings {
+            valid_from,
+            valid_until,
+            ..shared_settings()
+        };
+
+        let violations = check_shared_constraints(&context(), &shared, 999, &mut *conn)
+            .await
+            .unwrap();
+
+        assert_eq!(
+            violations
+                .iter()
+                .any(|violation| matches!(violation, EvalViolation::InvalidTime)),
+            expect_invalid_time
+        );
+
+        if expect_invalid_time {
+            assert_eq!(violations.len(), 1);
+        } else {
+            assert!(violations.is_empty());
+        }
+    }
+
+    #[rstest]
+    #[case::max_fee_within_limit(Some(U256::from(100u64)), None, 100, 10, false)]
+    #[case::max_fee_exceeded(Some(U256::from(99u64)), None, 100, 10, true)]
+    #[case::priority_fee_within_limit(None, Some(U256::from(10u64)), 100, 10, false)]
+    #[case::priority_fee_exceeded(None, Some(U256::from(9u64)), 100, 10, true)]
+    #[tokio::test]
+    async fn check_shared_constraints_enforces_gas_fee_caps(
+        #[case] max_gas_fee_per_gas: Option<U256>,
+        #[case] max_priority_fee_per_gas: Option<U256>,
+        #[case] actual_max_fee_per_gas: u128,
+        #[case] actual_max_priority_fee_per_gas: u128,
+        #[case] expect_gas_limit_violation: bool,
+    ) {
+        let db = db::create_test_pool().await;
+        let mut conn = db.get().await.unwrap();
+
+        let context = EvalContext {
+            max_fee_per_gas: actual_max_fee_per_gas,
+            max_priority_fee_per_gas: actual_max_priority_fee_per_gas,
+            ..context()
+        };
+
+        let shared = SharedGrantSettings {
+            max_gas_fee_per_gas,
+            max_priority_fee_per_gas,
+            ..shared_settings()
+        };
+        let violations = check_shared_constraints(&context, &shared, 999, &mut *conn)
+            .await
+            .unwrap();
+
+        assert_eq!(
+            violations
+                .iter()
+                .any(|violation| matches!(violation, EvalViolation::GasLimitExceeded { .. })),
+            expect_gas_limit_violation
+        );
+
+        if expect_gas_limit_violation {
+            assert_eq!(violations.len(), 1);
+        } else {
+            assert!(violations.is_empty());
+        }
+    }
+
+    #[rstest]
+    #[case::under_rate_limit(2, false)]
+    #[case::at_rate_limit(1, true)]
+    #[tokio::test]
+    async fn check_shared_constraints_enforces_rate_limit(
+        #[case] rate_limit_count: u32,
+        #[case] expect_rate_limit_violation: bool,
+    ) {
+        let db = db::create_test_pool().await;
+        let mut conn = db.get().await.unwrap();
+
+        let shared = SharedGrantSettings {
+            rate_limit: Some(TransactionRateLimit {
+                count: rate_limit_count,
+                window: Duration::hours(1),
+            }),
+            ..shared_settings()
+        };
+
+        let basic_grant = insert_basic_grant(&mut conn, &shared).await;
+
+        insert_into(evm_transaction_log::table)
+            .values(NewEvmTransactionLog {
+                grant_id: basic_grant.id,
+                wallet_access_id: WALLET_ACCESS_ID,
+                chain_id: CHAIN_ID as i32,
+                eth_value: super::utils::u256_to_bytes(U256::ZERO).to_vec(),
+                signed_at: SqliteTimestamp(Utc::now()),
+            })
+            .execute(&mut *conn)
+            .await
+            .unwrap();
+
+        let violations = check_shared_constraints(&context(), &shared, basic_grant.id, &mut *conn)
+            .await
+            .unwrap();
+
+        assert_eq!(
+            violations
+                .iter()
+                .any(|violation| matches!(violation, EvalViolation::RateLimitExceeded)),
+            expect_rate_limit_violation
+        );
+
+        if expect_rate_limit_violation {
+            assert_eq!(violations.len(), 1);
+        } else {
+            assert!(violations.is_empty());
+        }
+    }
+}
--- a/server/crates/arbiter-server/src/evm/policies.rs
+++ b/server/crates/arbiter-server/src/evm/policies.rs
@@ -10,6 +10,7 @@ use diesel_async::{AsyncConnection, RunQueryDsl};
 use thiserror::Error;

 use crate::{
+    crypto::integrity::v1::Integrable,
    db::models::{self, EvmBasicGrant, EvmWalletAccess},
    evm::utils,
 };
@@ -55,6 +56,9 @@ pub enum EvalViolation {

    #[error("Transaction type is not allowed by this grant")]
    InvalidTransactionType,
+
+    #[error("Mismatching chain ID")]
+    MismatchingChainId { expected: ChainId, actual: ChainId },
 }

 pub type DatabaseID = i32;
@@ -62,13 +66,12 @@ pub type DatabaseID = i32;
 #[derive(Debug)]
 pub struct Grant<PolicySettings> {
    pub id: DatabaseID,
-    pub shared_grant_id: DatabaseID, // ID of the basic grant for shared-logic checks like rate limits and validity periods
-    pub shared: SharedGrantSettings,
-    pub settings: PolicySettings,
+    pub common_settings_id: DatabaseID, // ID of the basic grant for shared-logic checks like rate limits and validity periods
+    pub settings: CombinedSettings<PolicySettings>,
 }

 pub trait Policy: Sized {
-    type Settings: Send + Sync + 'static + Into<SpecificGrant>;
+    type Settings: Send + Sync + 'static + Into<SpecificGrant> + Integrable;
    type Meaning: Display + std::fmt::Debug + Send + Sync + 'static + Into<SpecificMeaning>;

    fn analyze(context: &EvalContext) -> Option<Self::Meaning>;
@@ -124,19 +127,19 @@ pub enum SpecificMeaning {
    TokenTransfer(token_transfers::Meaning),
 }

-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, arbiter_macros::Hashable)]
 pub struct TransactionRateLimit {
    pub count: u32,
    pub window: Duration,
 }

-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, arbiter_macros::Hashable)]
 pub struct VolumeRateLimit {
    pub max_volume: U256,
    pub window: Duration,
 }

-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, arbiter_macros::Hashable)]
 pub struct SharedGrantSettings {
    pub wallet_access_id: i32,
    pub chain: ChainId,
@@ -151,7 +154,7 @@ pub struct SharedGrantSettings {
 }

 impl SharedGrantSettings {
-    fn try_from_model(model: EvmBasicGrant) -> QueryResult<Self> {
+    pub(crate) fn try_from_model(model: EvmBasicGrant) -> QueryResult<Self> {
        Ok(Self {
            wallet_access_id: model.wallet_access_id,
            chain: model.chain_id as u64, // safe because chain_id is stored as i32 but is guaranteed to be a valid ChainId by the API when creating grants
@@ -197,7 +200,22 @@ pub enum SpecificGrant {
    TokenTransfer(token_transfers::Settings),
 }

-pub struct FullGrant<PolicyGrant> {
-    pub basic: SharedGrantSettings,
+#[derive(Debug, arbiter_macros::Hashable)]
+pub struct CombinedSettings<PolicyGrant> {
+    pub shared: SharedGrantSettings,
    pub specific: PolicyGrant,
 }
+
+impl<P> CombinedSettings<P> {
+    pub fn generalize<Y: From<P>>(self) -> CombinedSettings<Y> {
+        CombinedSettings {
+            shared: self.shared,
+            specific: self.specific.into(),
+        }
+    }
+}
+
+impl<P: Integrable> Integrable for CombinedSettings<P> {
+    const KIND: &'static str = P::KIND;
+    const VERSION: i32 = P::VERSION;
+}
--- a/server/crates/arbiter-server/src/evm/policies/ether_transfer/mod.rs
+++ b/server/crates/arbiter-server/src/evm/policies/ether_transfer/mod.rs
@@ -8,13 +8,14 @@ use diesel::sqlite::Sqlite;
 use diesel::{ExpressionMethods, JoinOnDsl, prelude::*};
 use diesel_async::{AsyncConnection, RunQueryDsl};

+use crate::crypto::integrity::v1::Integrable;
 use crate::db::models::{
    EvmBasicGrant, EvmEtherTransferGrant, EvmEtherTransferGrantTarget, EvmEtherTransferLimit,
    NewEvmEtherTransferLimit, SqliteTimestamp,
 };
 use crate::db::schema::{evm_basic_grant, evm_ether_transfer_limit, evm_transaction_log};
 use crate::evm::policies::{
-    Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning, VolumeRateLimit,
+    CombinedSettings, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning, VolumeRateLimit,
 };
 use crate::{
    db::{
@@ -51,11 +52,14 @@ impl From<Meaning> for SpecificMeaning {
 }

 // A grant for ether transfers, which can be scoped to specific target addresses and volume limits
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, arbiter_macros::Hashable)]
 pub struct Settings {
    pub target: Vec<Address>,
    pub limit: VolumeRateLimit,
 }
+impl Integrable for Settings {
+    const KIND: &'static str = "EtherTransfer";
+}

 impl From<Settings> for SpecificGrant {
    fn from(val: Settings) -> SpecificGrant {
@@ -95,17 +99,17 @@ async fn check_rate_limits(
    db: &mut impl AsyncConnection<Backend = Sqlite>,
 ) -> QueryResult<Vec<EvalViolation>> {
    let mut violations = Vec::new();
-    let window = grant.settings.limit.window;
+    let window = grant.settings.specific.limit.window;

    let past_transaction = query_relevant_past_transaction(grant.id, window, db).await?;

-    let window_start = chrono::Utc::now() - grant.settings.limit.window;
+    let window_start = chrono::Utc::now() - grant.settings.specific.limit.window;
    let prospective_cumulative_volume: U256 = past_transaction
        .iter()
        .filter(|(_, timestamp)| timestamp >= &window_start)
        .fold(current_transfer_value, |acc, (value, _)| acc + *value);

-    if prospective_cumulative_volume > grant.settings.limit.max_volume {
+    if prospective_cumulative_volume > grant.settings.specific.limit.max_volume {
        violations.push(EvalViolation::VolumetricLimitExceeded);
    }

@@ -138,7 +142,7 @@ impl Policy for EtherTransfer {
        let mut violations = Vec::new();

        // Check if the target address is within the grant's allowed targets
-        if !grant.settings.target.contains(&meaning.to) {
+        if !grant.settings.specific.target.contains(&meaning.to) {
            violations.push(EvalViolation::InvalidTarget { target: meaning.to });
        }

@@ -247,9 +251,11 @@ impl Policy for EtherTransfer {

        Ok(Some(Grant {
            id: grant.id,
-            shared_grant_id: grant.basic_grant_id,
+            common_settings_id: grant.basic_grant_id,
+            settings: CombinedSettings {
                shared: SharedGrantSettings::try_from_model(basic_grant)?,
-            settings,
+                specific: settings,
+            },
        }))
    }

@@ -327,9 +333,10 @@ impl Policy for EtherTransfer {

                Ok(Grant {
                    id: specific.id,
-                    shared_grant_id: specific.basic_grant_id,
+                    common_settings_id: specific.basic_grant_id,
+                    settings: CombinedSettings {
                        shared: SharedGrantSettings::try_from_model(basic)?,
-                    settings: Settings {
+                        specific: Settings {
                            target: targets,
                            limit: VolumeRateLimit {
                                max_volume: utils::try_bytes_to_u256(&limit.max_volume).map_err(
@@ -338,6 +345,7 @@ impl Policy for EtherTransfer {
                                window: Duration::seconds(limit.window_secs as i64),
                            },
                        },
+                    },
                })
            })
            .collect()
--- a/server/crates/arbiter-server/src/evm/policies/ether_transfer/tests.rs
+++ b/server/crates/arbiter-server/src/evm/policies/ether_transfer/tests.rs
@@ -11,7 +11,10 @@ use crate::db::{
    schema::{evm_basic_grant, evm_transaction_log},
 };
 use crate::evm::{
-    policies::{EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings, VolumeRateLimit},
+    policies::{
+        CombinedSettings, EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings,
+        VolumeRateLimit,
+    },
    utils,
 };

@@ -81,8 +84,6 @@ fn shared() -> SharedGrantSettings {
    }
 }

-// ── analyze ─────────────────────────────────────────────────────────────
-
 #[test]
 fn analyze_matches_empty_calldata() {
    let m = EtherTransfer::analyze(&ctx(ALLOWED, U256::from(1_000u64))).unwrap();
@@ -99,8 +100,6 @@ fn analyze_rejects_nonempty_calldata() {
    assert!(EtherTransfer::analyze(&context).is_none());
 }

-// ── evaluate ────────────────────────────────────────────────────────────
-
 #[tokio::test]
 async fn evaluate_passes_for_allowed_target() {
    let db = db::create_test_pool().await;
@@ -108,9 +107,11 @@ async fn evaluate_passes_for_allowed_target() {

    let grant = Grant {
        id: 999,
-        shared_grant_id: 999,
+        common_settings_id: 999,
+        settings: CombinedSettings {
            shared: shared(),
-        settings: make_settings(vec![ALLOWED], 1_000_000),
+            specific: make_settings(vec![ALLOWED], 1_000_000),
+        },
    };
    let context = ctx(ALLOWED, U256::from(100u64));
    let m = EtherTransfer::analyze(&context).unwrap();
@@ -127,9 +128,11 @@ async fn evaluate_rejects_disallowed_target() {

    let grant = Grant {
        id: 999,
-        shared_grant_id: 999,
+        common_settings_id: 999,
+        settings: CombinedSettings {
            shared: shared(),
-        settings: make_settings(vec![ALLOWED], 1_000_000),
+            specific: make_settings(vec![ALLOWED], 1_000_000),
+        },
    };
    let context = ctx(OTHER, U256::from(100u64));
    let m = EtherTransfer::analyze(&context).unwrap();
@@ -167,9 +170,11 @@ async fn evaluate_passes_when_volume_within_limit() {

    let grant = Grant {
        id: grant_id,
-        shared_grant_id: basic.id,
+        common_settings_id: basic.id,
+        settings: CombinedSettings {
            shared: shared(),
-        settings,
+            specific: settings,
+        },
    };
    let context = ctx(ALLOWED, U256::from(100u64));
    let m = EtherTransfer::analyze(&context).unwrap();
@@ -207,9 +212,11 @@ async fn evaluate_rejects_volume_over_limit() {

    let grant = Grant {
        id: grant_id,
-        shared_grant_id: basic.id,
+        common_settings_id: basic.id,
+        settings: CombinedSettings {
            shared: shared(),
-        settings,
+            specific: settings,
+        },
    };
    let context = ctx(ALLOWED, U256::from(1u64));
    let m = EtherTransfer::analyze(&context).unwrap();
@@ -248,9 +255,11 @@ async fn evaluate_passes_at_exactly_volume_limit() {

    let grant = Grant {
        id: grant_id,
-        shared_grant_id: basic.id,
+        common_settings_id: basic.id,
+        settings: CombinedSettings {
            shared: shared(),
-        settings,
+            specific: settings,
+        },
    };
    let context = ctx(ALLOWED, U256::from(100u64));
    let m = EtherTransfer::analyze(&context).unwrap();
@@ -263,8 +272,6 @@ async fn evaluate_passes_at_exactly_volume_limit() {
    );
 }

-// ── try_find_grant ───────────────────────────────────────────────────────
-
 #[tokio::test]
 async fn try_find_grant_roundtrip() {
    let db = db::create_test_pool().await;
@@ -282,8 +289,11 @@ async fn try_find_grant_roundtrip() {

    assert!(found.is_some());
    let g = found.unwrap();
-    assert_eq!(g.settings.target, vec![ALLOWED]);
-    assert_eq!(g.settings.limit.max_volume, U256::from(1_000_000u64));
+    assert_eq!(g.settings.specific.target, vec![ALLOWED]);
+    assert_eq!(
+        g.settings.specific.limit.max_volume,
+        U256::from(1_000_000u64)
+    );
 }

 #[tokio::test]
@@ -320,7 +330,36 @@ async fn try_find_grant_wrong_target_returns_none() {
    assert!(found.is_none());
 }

-// ── find_all_grants ──────────────────────────────────────────────────────
+proptest::proptest! {
+    #[test]
+    fn target_order_does_not_affect_hash(
+        raw_addrs in proptest::collection::vec(proptest::prelude::any::<[u8; 20]>(), 0..8),
+        seed in proptest::prelude::any::<u64>(),
+        max_volume in proptest::prelude::any::<u64>(),
+        window_secs in 1i64..=86400,
+    ) {
+        use rand::{SeedableRng, seq::SliceRandom};
+        use sha2::Digest;
+        use arbiter_crypto::hashing::Hashable;
+
+        let addrs: Vec<Address> = raw_addrs.iter().map(|b| Address::from(*b)).collect();
+        let mut shuffled = addrs.clone();
+        shuffled.shuffle(&mut rand::rngs::StdRng::seed_from_u64(seed));
+
+        let limit = VolumeRateLimit {
+            max_volume: U256::from(max_volume),
+            window: Duration::seconds(window_secs),
+        };
+
+        let mut h1 = sha2::Sha256::new();
+        Settings { target: addrs, limit: limit.clone() }.hash(&mut h1);
+
+        let mut h2 = sha2::Sha256::new();
+        Settings { target: shuffled, limit }.hash(&mut h2);
+
+        proptest::prop_assert_eq!(h1.finalize(), h2.finalize());
+    }
+}

 #[tokio::test]
 async fn find_all_grants_empty_db() {
@@ -347,7 +386,7 @@ async fn find_all_grants_excludes_revoked() {

    let all = EtherTransfer::find_all_grants(&mut *conn).await.unwrap();
    assert_eq!(all.len(), 1);
-    assert_eq!(all[0].settings.target, vec![ALLOWED]);
+    assert_eq!(all[0].settings.specific.target, vec![ALLOWED]);
 }

 #[tokio::test]
@@ -363,8 +402,11 @@ async fn find_all_grants_multiple_targets() {

    let all = EtherTransfer::find_all_grants(&mut *conn).await.unwrap();
    assert_eq!(all.len(), 1);
-    assert_eq!(all[0].settings.target.len(), 2);
-    assert_eq!(all[0].settings.limit.max_volume, U256::from(1_000_000u64));
+    assert_eq!(all[0].settings.specific.target.len(), 2);
+    assert_eq!(
+        all[0].settings.specific.limit.max_volume,
+        U256::from(1_000_000u64)
+    );
 }

 #[tokio::test]
--- a/server/crates/arbiter-server/src/evm/policies/token_transfers/mod.rs
+++ b/server/crates/arbiter-server/src/evm/policies/token_transfers/mod.rs
@@ -1,20 +1,5 @@
 use std::collections::HashMap;

-use alloy::{
-    primitives::{Address, U256},
-    sol_types::SolCall,
-};
-use arbiter_tokens_registry::evm::nonfungible::{self, TokenInfo};
-use chrono::{DateTime, Duration, Utc};
-use diesel::dsl::{auto_type, insert_into};
-use diesel::sqlite::Sqlite;
-use diesel::{ExpressionMethods, prelude::*};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-
-use crate::db::models::{
-    EvmBasicGrant, EvmTokenTransferGrant, EvmTokenTransferVolumeLimit, NewEvmTokenTransferGrant,
-    NewEvmTokenTransferLog, NewEvmTokenTransferVolumeLimit, SqliteTimestamp,
-};
 use crate::db::schema::{
    evm_basic_grant, evm_token_transfer_grant, evm_token_transfer_log,
    evm_token_transfer_volume_limit,
@@ -26,6 +11,25 @@ use crate::evm::{
    },
    utils,
 };
+use crate::{
+    crypto::integrity::Integrable,
+    db::models::{
+        EvmBasicGrant, EvmTokenTransferGrant, EvmTokenTransferVolumeLimit,
+        NewEvmTokenTransferGrant, NewEvmTokenTransferLog, NewEvmTokenTransferVolumeLimit,
+        SqliteTimestamp,
+    },
+    evm::policies::CombinedSettings,
+};
+use alloy::{
+    primitives::{Address, U256},
+    sol_types::SolCall,
+};
+use arbiter_tokens_registry::evm::nonfungible::{self, TokenInfo};
+use chrono::{DateTime, Duration, Utc};
+use diesel::dsl::{auto_type, insert_into};
+use diesel::sqlite::Sqlite;
+use diesel::{ExpressionMethods, prelude::*};
+use diesel_async::{AsyncConnection, RunQueryDsl};

 use super::{DatabaseID, EvalContext, EvalViolation};

@@ -38,9 +42,9 @@ fn grant_join() -> _ {

 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub struct Meaning {
-    pub(crate) token: &'static TokenInfo,
-    pub(crate) to: Address,
-    pub(crate) value: U256,
+    pub token: &'static TokenInfo,
+    pub to: Address,
+    pub value: U256,
 }
 impl std::fmt::Display for Meaning {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
@@ -58,12 +62,16 @@ impl From<Meaning> for SpecificMeaning {
 }

 // A grant for token transfers, which can be scoped to specific target addresses and volume limits
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, arbiter_macros::Hashable)]
 pub struct Settings {
    pub token_contract: Address,
    pub target: Option<Address>,
    pub volume_limits: Vec<VolumeRateLimit>,
 }
+impl Integrable for Settings {
+    const KIND: &'static str = "TokenTransfer";
+}
+
 impl From<Settings> for SpecificGrant {
    fn from(val: Settings) -> SpecificGrant {
        SpecificGrant::TokenTransfer(val)
@@ -106,13 +114,20 @@ async fn check_volume_rate_limits(
 ) -> QueryResult<Vec<EvalViolation>> {
    let mut violations = Vec::new();

-    let Some(longest_window) = grant.settings.volume_limits.iter().map(|l| l.window).max() else {
+    let Some(longest_window) = grant
+        .settings
+        .specific
+        .volume_limits
+        .iter()
+        .map(|l| l.window)
+        .max()
+    else {
        return Ok(violations);
    };

    let past_transfers = query_relevant_past_transfers(grant.id, longest_window, db).await?;

-    for limit in &grant.settings.volume_limits {
+    for limit in &grant.settings.specific.volume_limits {
        let window_start = chrono::Utc::now() - limit.window;
        let prospective_cumulative_volume: U256 = past_transfers
            .iter()
@@ -158,7 +173,7 @@ impl Policy for TokenTransfer {
            return Ok(violations);
        }

-        if let Some(allowed) = grant.settings.target
+        if let Some(allowed) = grant.settings.specific.target
            && allowed != meaning.to
        {
            violations.push(EvalViolation::InvalidTarget { target: meaning.to });
@@ -269,9 +284,11 @@ impl Policy for TokenTransfer {

        Ok(Some(Grant {
            id: token_grant.id,
-            shared_grant_id: token_grant.basic_grant_id,
+            common_settings_id: token_grant.basic_grant_id,
+            settings: CombinedSettings {
                shared: SharedGrantSettings::try_from_model(basic_grant)?,
-            settings,
+                specific: settings,
+            },
        }))
    }

@@ -369,13 +386,15 @@ impl Policy for TokenTransfer {

                Ok(Grant {
                    id: specific.id,
-                    shared_grant_id: specific.basic_grant_id,
+                    common_settings_id: specific.basic_grant_id,
+                    settings: CombinedSettings {
                        shared: SharedGrantSettings::try_from_model(basic)?,
-                    settings: Settings {
+                        specific: Settings {
                            token_contract: Address::from(token_contract),
                            target,
                            volume_limits,
                        },
+                    },
                })
            })
            .collect()
--- a/server/crates/arbiter-server/src/evm/policies/token_transfers/tests.rs
+++ b/server/crates/arbiter-server/src/evm/policies/token_transfers/tests.rs
@@ -11,7 +11,10 @@ use crate::db::{
 };
 use crate::evm::{
    abi::IERC20::transferCall,
-    policies::{EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings, VolumeRateLimit},
+    policies::{
+        CombinedSettings, EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings,
+        VolumeRateLimit,
+    },
    utils,
 };

@@ -98,8 +101,6 @@ fn shared() -> SharedGrantSettings {
    }
 }

-// ── analyze ─────────────────────────────────────────────────────────────
-
 #[test]
 fn analyze_known_token_valid_calldata() {
    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
@@ -125,8 +126,6 @@ fn analyze_empty_calldata_returns_none() {
    assert!(TokenTransfer::analyze(&ctx(DAI, Bytes::new())).is_none());
 }

-// ── evaluate ────────────────────────────────────────────────────────────
-
 #[tokio::test]
 async fn evaluate_rejects_nonzero_eth_value() {
    let db = db::create_test_pool().await;
@@ -134,9 +133,11 @@ async fn evaluate_rejects_nonzero_eth_value() {

    let grant = Grant {
        id: 999,
-        shared_grant_id: 999,
+        common_settings_id: 999,
+        settings: CombinedSettings {
            shared: shared(),
-        settings: make_settings(None, None),
+            specific: make_settings(None, None),
+        },
    };
    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
    let mut context = ctx(DAI, calldata);
@@ -163,9 +164,11 @@ async fn evaluate_passes_any_recipient_when_no_restriction() {

    let grant = Grant {
        id: 999,
-        shared_grant_id: 999,
+        common_settings_id: 999,
+        settings: CombinedSettings {
            shared: shared(),
-        settings: make_settings(None, None),
+            specific: make_settings(None, None),
+        },
    };
    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
    let context = ctx(DAI, calldata);
@@ -183,9 +186,11 @@ async fn evaluate_passes_matching_restricted_recipient() {

    let grant = Grant {
        id: 999,
-        shared_grant_id: 999,
+        common_settings_id: 999,
+        settings: CombinedSettings {
            shared: shared(),
-        settings: make_settings(Some(RECIPIENT), None),
+            specific: make_settings(Some(RECIPIENT), None),
+        },
    };
    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
    let context = ctx(DAI, calldata);
@@ -203,9 +208,11 @@ async fn evaluate_rejects_wrong_restricted_recipient() {

    let grant = Grant {
        id: 999,
-        shared_grant_id: 999,
+        common_settings_id: 999,
+        settings: CombinedSettings {
            shared: shared(),
-        settings: make_settings(Some(RECIPIENT), None),
+            specific: make_settings(Some(RECIPIENT), None),
+        },
    };
    let calldata = transfer_calldata(OTHER, U256::from(100u64));
    let context = ctx(DAI, calldata);
@@ -247,9 +254,11 @@ async fn evaluate_passes_volume_at_exact_limit() {

    let grant = Grant {
        id: grant_id,
-        shared_grant_id: basic.id,
+        common_settings_id: basic.id,
+        settings: CombinedSettings {
            shared: shared(),
-        settings,
+            specific: settings,
+        },
    };
    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
    let context = ctx(DAI, calldata);
@@ -290,9 +299,11 @@ async fn evaluate_rejects_volume_over_limit() {

    let grant = Grant {
        id: grant_id,
-        shared_grant_id: basic.id,
+        common_settings_id: basic.id,
+        settings: CombinedSettings {
            shared: shared(),
-        settings,
+            specific: settings,
+        },
    };
    let calldata = transfer_calldata(RECIPIENT, U256::from(1u64));
    let context = ctx(DAI, calldata);
@@ -313,9 +324,11 @@ async fn evaluate_no_volume_limits_always_passes() {

    let grant = Grant {
        id: 999,
-        shared_grant_id: 999,
+        common_settings_id: 999,
+        settings: CombinedSettings {
            shared: shared(),
-        settings: make_settings(None, None), // no volume limits
+            specific: make_settings(None, None), // no volume limits
+        },
    };
    let calldata = transfer_calldata(RECIPIENT, U256::from(u64::MAX));
    let context = ctx(DAI, calldata);
@@ -349,10 +362,13 @@ async fn try_find_grant_roundtrip() {

    assert!(found.is_some());
    let g = found.unwrap();
-    assert_eq!(g.settings.token_contract, DAI);
-    assert_eq!(g.settings.target, Some(RECIPIENT));
-    assert_eq!(g.settings.volume_limits.len(), 1);
-    assert_eq!(g.settings.volume_limits[0].max_volume, U256::from(5_000u64));
+    assert_eq!(g.settings.specific.token_contract, DAI);
+    assert_eq!(g.settings.specific.target, Some(RECIPIENT));
+    assert_eq!(g.settings.specific.volume_limits.len(), 1);
+    assert_eq!(
+        g.settings.specific.volume_limits[0].max_volume,
+        U256::from(5_000u64)
+    );
 }

 #[tokio::test]
@@ -392,7 +408,39 @@ async fn try_find_grant_unknown_token_returns_none() {
    assert!(found.is_none());
 }

-// ── find_all_grants ──────────────────────────────────────────────────────
+proptest::proptest! {
+    #[test]
+    fn volume_limits_order_does_not_affect_hash(
+        raw_limits in proptest::collection::vec(
+            (proptest::prelude::any::<u64>(), 1i64..=86400),
+            0..8,
+        ),
+        seed in proptest::prelude::any::<u64>(),
+    ) {
+        use rand::{SeedableRng, seq::SliceRandom};
+        use sha2::Digest;
+        use arbiter_crypto::hashing::Hashable;
+
+        let limits: Vec<VolumeRateLimit> = raw_limits
+            .iter()
+            .map(|(max_vol, window_secs)| VolumeRateLimit {
+                max_volume: U256::from(*max_vol),
+                window: Duration::seconds(*window_secs),
+            })
+            .collect();
+
+        let mut shuffled = limits.clone();
+        shuffled.shuffle(&mut rand::rngs::StdRng::seed_from_u64(seed));
+
+        let mut h1 = sha2::Sha256::new();
+        Settings { token_contract: DAI, target: None, volume_limits: limits }.hash(&mut h1);
+
+        let mut h2 = sha2::Sha256::new();
+        Settings { token_contract: DAI, target: None, volume_limits: shuffled }.hash(&mut h2);
+
+        proptest::prop_assert_eq!(h1.finalize(), h2.finalize());
+    }
+}

 #[tokio::test]
 async fn find_all_grants_empty_db() {
@@ -434,9 +482,9 @@ async fn find_all_grants_loads_volume_limits() {

    let all = TokenTransfer::find_all_grants(&mut *conn).await.unwrap();
    assert_eq!(all.len(), 1);
-    assert_eq!(all[0].settings.volume_limits.len(), 1);
+    assert_eq!(all[0].settings.specific.volume_limits.len(), 1);
    assert_eq!(
-        all[0].settings.volume_limits[0].max_volume,
+        all[0].settings.specific.volume_limits[0].max_volume,
        U256::from(9_999u64)
    );
 }
--- a/server/crates/arbiter-server/src/evm/safe_signer.rs
+++ b/server/crates/arbiter-server/src/evm/safe_signer.rs
@@ -1,12 +1,12 @@
 use std::sync::Mutex;

-use crate::safe_cell::{SafeCell, SafeCellHandle as _};
 use alloy::{
    consensus::SignableTransaction,
    network::{TxSigner, TxSignerSync},
    primitives::{Address, B256, ChainId, Signature},
    signers::{Error, Result, Signer, SignerSync, utils::secret_key_to_address},
 };
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use async_trait::async_trait;
 use k256::ecdsa::{self, RecoveryId, SigningKey, signature::hazmat::PrehashSigner};

--- a/server/crates/arbiter-server/src/grpc/client/auth.rs
+++ b/server/crates/arbiter-server/src/grpc/client/auth.rs
@@ -1,3 +1,4 @@
+use arbiter_crypto::authn;
 use arbiter_proto::{
    ClientMetadata,
    proto::{
@@ -45,7 +46,7 @@ impl<'a> AuthTransportAdapter<'a> {
        match response {
            auth::Outbound::AuthChallenge { pubkey, nonce } => {
                AuthResponsePayload::Challenge(ProtoAuthChallenge {
-                    pubkey: pubkey.to_bytes().to_vec(),
+                    pubkey: pubkey.to_bytes(),
                    nonce,
                })
            }
@@ -68,6 +69,7 @@ impl<'a> AuthTransportAdapter<'a> {
                auth::Error::ApproveError(auth::ApproveError::Internal)
                | auth::Error::DatabasePoolUnavailable
                | auth::Error::DatabaseOperationFailed
+                | auth::Error::IntegrityCheckFailed
                | auth::Error::Transport => ProtoAuthResult::Internal,
            }
            .into(),
@@ -159,11 +161,7 @@ impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
                        .await;
                    return None;
                };
-                let Ok(pubkey) = <[u8; 32]>::try_from(pubkey) else {
-                    let _ = self.send_auth_result(ProtoAuthResult::InvalidKey).await;
-                    return None;
-                };
-                let Ok(pubkey) = ed25519_dalek::VerifyingKey::from_bytes(&pubkey) else {
+                let Ok(pubkey) = authn::PublicKey::try_from(pubkey.as_slice()) else {
                    let _ = self.send_auth_result(ProtoAuthResult::InvalidKey).await;
                    return None;
                };
@@ -173,7 +171,7 @@ impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
                })
            }
            AuthRequestPayload::ChallengeSolution(ProtoAuthChallengeSolution { signature }) => {
-                let Ok(signature) = ed25519_dalek::Signature::try_from(signature.as_slice()) else {
+                let Ok(signature) = authn::Signature::try_from(signature.as_slice()) else {
                    let _ = self
                        .send_auth_result(ProtoAuthResult::InvalidSignature)
                        .await;
--- a/server/crates/arbiter-server/src/grpc/common/outbound.rs
+++ b/server/crates/arbiter-server/src/grpc/common/outbound.rs
@@ -8,7 +8,7 @@ use arbiter_proto::proto::{
        EvalViolation as ProtoEvalViolation, GasLimitExceededViolation, NoMatchingGrantError,
        PolicyViolationsError, SpecificMeaning as ProtoSpecificMeaning,
        TokenInfo as ProtoTokenInfo, TransactionEvalError as ProtoTransactionEvalError,
-        eval_violation::Kind as ProtoEvalViolationKind,
+        eval_violation as proto_eval_violation, eval_violation::Kind as ProtoEvalViolationKind,
        specific_meaning::Meaning as ProtoSpecificMeaningKind,
        transaction_eval_error::Kind as ProtoTransactionEvalErrorKind,
    },
@@ -79,6 +79,12 @@ impl Convert for EvalViolation {
            EvalViolation::InvalidTransactionType => {
                ProtoEvalViolationKind::InvalidTransactionType(())
            }
+            EvalViolation::MismatchingChainId { expected, actual } => {
+                ProtoEvalViolationKind::ChainIdMismatch(proto_eval_violation::ChainIdMismatch {
+                    expected,
+                    actual,
+                })
+            }
        };

        ProtoEvalViolation { kind: Some(kind) }
@@ -108,12 +114,12 @@ impl Convert for VetError {
                        violations: violations.into_iter().map(Convert::convert).collect(),
                    })
                }
-                PolicyError::Database(_) => {
+                PolicyError::Database(_) | PolicyError::Integrity(_) => {
                    return EvmSignTransactionResult::Error(ProtoEvmError::Internal.into());
                }
            },
        };

-        EvmSignTransactionResult::EvalError(ProtoTransactionEvalError { kind: Some(kind) }.into())
+        EvmSignTransactionResult::EvalError(ProtoTransactionEvalError { kind: Some(kind) })
    }
 }
--- a/server/crates/arbiter-server/src/grpc/user_agent/auth.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/auth.rs
@@ -1,3 +1,4 @@
+use arbiter_crypto::authn;
 use arbiter_proto::{
    proto::user_agent::{
        UserAgentRequest, UserAgentResponse,
@@ -5,8 +6,7 @@ use arbiter_proto::{
            self as proto_auth, AuthChallenge as ProtoAuthChallenge,
            AuthChallengeRequest as ProtoAuthChallengeRequest,
            AuthChallengeSolution as ProtoAuthChallengeSolution, AuthResult as ProtoAuthResult,
-            KeyType as ProtoKeyType, request::Payload as AuthRequestPayload,
-            response::Payload as AuthResponsePayload,
+            request::Payload as AuthRequestPayload, response::Payload as AuthResponsePayload,
        },
        user_agent_request::Payload as UserAgentRequestPayload,
        user_agent_response::Payload as UserAgentResponsePayload,
@@ -18,8 +18,7 @@ use tonic::Status;
 use tracing::warn;

 use crate::{
-    actors::user_agent::{AuthPublicKey, UserAgentConnection, auth},
-    db::models::KeyType,
+    actors::user_agent::{UserAgentConnection, auth},
    grpc::request_tracker::RequestTracker,
 };

@@ -141,28 +140,9 @@ impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
            AuthRequestPayload::ChallengeRequest(ProtoAuthChallengeRequest {
                pubkey,
                bootstrap_token,
-                key_type,
+                key_type: _,
            }) => {
-                let Ok(key_type) = ProtoKeyType::try_from(key_type) else {
-                    warn!(
-                        event = "received request with invalid key type",
-                        "grpc.useragent.auth_adapter"
-                    );
-                    return None;
-                };
-                let key_type = match key_type {
-                    ProtoKeyType::Ed25519 => KeyType::Ed25519,
-                    ProtoKeyType::EcdsaSecp256k1 => KeyType::EcdsaSecp256k1,
-                    ProtoKeyType::Rsa => KeyType::Rsa,
-                    ProtoKeyType::Unspecified => {
-                        warn!(
-                            event = "received request with unspecified key type",
-                            "grpc.useragent.auth_adapter"
-                        );
-                        return None;
-                    }
-                };
-                let Ok(pubkey) = AuthPublicKey::try_from((key_type, pubkey)) else {
+                let Ok(pubkey) = authn::PublicKey::try_from(pubkey.as_slice()) else {
                    warn!(
                        event = "received request with invalid public key",
                        "grpc.useragent.auth_adapter"
@@ -188,7 +168,7 @@ pub async fn start(
    conn: &mut UserAgentConnection,
    bi: &mut GrpcBi<UserAgentRequest, UserAgentResponse>,
    request_tracker: &mut RequestTracker,
-) -> Result<AuthPublicKey, auth::Error> {
+) -> Result<authn::PublicKey, auth::Error> {
    let transport = AuthTransportAdapter::new(bi, request_tracker);
    auth::authenticate(conn, transport).await
 }
--- a/server/crates/arbiter-server/src/grpc/user_agent/evm.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/evm.rs
@@ -26,8 +26,8 @@ use crate::{
    actors::user_agent::{
        UserAgentSession,
        session::connection::{
-            HandleEvmWalletCreate, HandleEvmWalletList, HandleGrantCreate, HandleGrantDelete,
-            HandleGrantList, HandleSignTransaction,
+            GrantMutationError, HandleEvmWalletCreate, HandleEvmWalletList, HandleGrantCreate,
+            HandleGrantDelete, HandleGrantList, HandleSignTransaction,
            SignTransactionError as SessionSignTransactionError,
        },
    },
@@ -114,10 +114,10 @@ async fn handle_grant_list(
            grants: grants
                .into_iter()
                .map(|grant| GrantEntry {
-                    id: grant.id,
-                    wallet_access_id: grant.shared.wallet_access_id,
-                    shared: Some(grant.shared.convert()),
-                    specific: Some(grant.settings.convert()),
+                    id: grant.common_settings_id,
+                    wallet_access_id: grant.settings.shared.wallet_access_id,
+                    shared: Some(grant.settings.shared.convert()),
+                    specific: Some(grant.settings.specific.convert()),
                })
                .collect(),
        }),
@@ -148,6 +148,9 @@ async fn handle_grant_create(

    let result = match actor.ask(HandleGrantCreate { basic, grant }).await {
        Ok(grant_id) => EvmGrantCreateResult::GrantId(grant_id),
+        Err(kameo::error::SendError::HandlerError(GrantMutationError::VaultSealed)) => {
+            EvmGrantCreateResult::Error(ProtoEvmError::VaultSealed.into())
+        }
        Err(err) => {
            warn!(error = ?err, "Failed to create EVM grant");
            EvmGrantCreateResult::Error(ProtoEvmError::Internal.into())
@@ -171,6 +174,9 @@ async fn handle_grant_delete(
        .await
    {
        Ok(()) => EvmGrantDeleteResult::Ok(()),
+        Err(kameo::error::SendError::HandlerError(GrantMutationError::VaultSealed)) => {
+            EvmGrantDeleteResult::Error(ProtoEvmError::VaultSealed.into())
+        }
        Err(err) => {
            warn!(error = ?err, "Failed to delete EVM grant");
            EvmGrantDeleteResult::Error(ProtoEvmError::Internal.into())
--- a/server/crates/arbiter-server/src/grpc/user_agent/sdk_client.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/sdk_client.rs
@@ -1,3 +1,4 @@
+use arbiter_crypto::authn;
 use arbiter_proto::proto::{
    shared::ClientInfo as ProtoClientMetadata,
    user_agent::{
@@ -41,7 +42,7 @@ pub(super) fn out_of_band_payload(oob: OutOfBand) -> UserAgentResponsePayload {
    match oob {
        OutOfBand::ClientConnectionRequest { profile } => wrap_sdk_client_response(
            SdkClientResponsePayload::ConnectionRequest(ProtoSdkClientConnectionRequest {
-                pubkey: profile.pubkey.to_bytes().to_vec(),
+                pubkey: profile.pubkey.to_bytes(),
                info: Some(ProtoClientMetadata {
                    name: profile.metadata.name,
                    description: profile.metadata.description,
@@ -51,7 +52,7 @@ pub(super) fn out_of_band_payload(oob: OutOfBand) -> UserAgentResponsePayload {
        ),
        OutOfBand::ClientConnectionCancel { pubkey } => wrap_sdk_client_response(
            SdkClientResponsePayload::ConnectionCancel(ProtoSdkClientConnectionCancel {
-                pubkey: pubkey.to_bytes().to_vec(),
+                pubkey: pubkey.to_bytes(),
            }),
        ),
    }
@@ -89,10 +90,8 @@ async fn handle_connection_response(
    actor: &ActorRef<UserAgentSession>,
    resp: ProtoSdkClientConnectionResponse,
 ) -> Result<Option<UserAgentResponsePayload>, Status> {
-    let pubkey_bytes = <[u8; 32]>::try_from(resp.pubkey)
-        .map_err(|_| Status::invalid_argument("Invalid Ed25519 public key length"))?;
-    let pubkey = ed25519_dalek::VerifyingKey::from_bytes(&pubkey_bytes)
-        .map_err(|_| Status::invalid_argument("Invalid Ed25519 public key"))?;
+    let pubkey = authn::PublicKey::try_from(resp.pubkey.as_slice())
+        .map_err(|_| Status::invalid_argument("Invalid ML-DSA public key"))?;

    actor
        .ask(HandleNewClientApprove {
@@ -117,7 +116,7 @@ async fn handle_list(
                .into_iter()
                .map(|(client, metadata)| ProtoSdkClientEntry {
                    id: client.id,
-                    pubkey: client.public_key,
+                    pubkey: client.public_key.to_vec(),
                    info: Some(ProtoClientMetadata {
                        name: metadata.name,
                        description: metadata.description,
--- a/server/crates/arbiter-server/src/lib.rs
+++ b/server/crates/arbiter-server/src/lib.rs
@@ -7,7 +7,6 @@ pub mod crypto;
 pub mod db;
 pub mod evm;
 pub mod grpc;
-pub mod safe_cell;
 pub mod utils;

 pub struct Server {
--- a/server/crates/arbiter-server/src/main.rs
+++ b/server/crates/arbiter-server/src/main.rs
@@ -10,6 +10,7 @@ use tracing::info;
 const PORT: u16 = 50051;

 #[tokio::main]
+#[mutants::skip]
 async fn main() -> anyhow::Result<()> {
    aws_lc_rs::default_provider().install_default().unwrap();

--- a/server/crates/arbiter-server/tests/client/auth.rs
+++ b/server/crates/arbiter-server/tests/client/auth.rs
@@ -1,13 +1,21 @@
+use arbiter_crypto::{
+    authn::{self, CLIENT_CONTEXT, format_challenge},
+    safecell::{SafeCell, SafeCellHandle as _},
+};
 use arbiter_proto::ClientMetadata;
 use arbiter_proto::transport::{Receiver, Sender};
-use arbiter_server::actors::GlobalActors;
 use arbiter_server::{
-    actors::client::{ClientConnection, auth, connect_client},
-    db,
+    actors::{
+        GlobalActors,
+        client::{ClientConnection, ClientCredentials, auth, connect_client},
+        keyholder::Bootstrap,
+    },
+    crypto::integrity,
+    db::{self, schema},
 };
 use diesel::{ExpressionMethods as _, NullableExpressionMethods as _, QueryDsl as _, insert_into};
 use diesel_async::RunQueryDsl;
-use ed25519_dalek::Signer as _;
+use ml_dsa::{KeyGen, MlDsa87, SigningKey, VerifyingKey, signature::Keypair as _};

 use super::common::ChannelTransport;

@@ -21,7 +29,8 @@ fn metadata(name: &str, description: Option<&str>, version: Option<&str>) -> Cli

 async fn insert_registered_client(
    db: &db::DatabasePool,
-    pubkey: Vec<u8>,
+    actors: &GlobalActors,
+    pubkey: VerifyingKey<MlDsa87>,
    metadata: &ClientMetadata,
 ) {
    use arbiter_server::db::schema::{client_metadata, program_client};
@@ -37,34 +46,90 @@ async fn insert_registered_client(
        .get_result(&mut conn)
        .await
        .unwrap();
-    insert_into(program_client::table)
+    let client_id: i32 = insert_into(program_client::table)
        .values((
-            program_client::public_key.eq(pubkey),
+            program_client::public_key.eq(pubkey.encode().to_vec()),
            program_client::metadata_id.eq(metadata_id),
        ))
+        .returning(program_client::id)
+        .get_result(&mut conn)
+        .await
+        .unwrap();
+
+    integrity::sign_entity(
+        &mut conn,
+        &actors.key_holder,
+        &ClientCredentials {
+            pubkey: pubkey.into(),
+            nonce: 1,
+        },
+        client_id,
+    )
+    .await
+    .unwrap();
+}
+
+fn sign_client_challenge(
+    key: &SigningKey<MlDsa87>,
+    nonce: i32,
+    pubkey: &authn::PublicKey,
+) -> authn::Signature {
+    let challenge = format_challenge(nonce, &pubkey.to_bytes());
+    key.signing_key()
+        .sign_deterministic(&challenge, CLIENT_CONTEXT)
+        .unwrap()
+        .into()
+}
+
+async fn insert_bootstrap_sentinel_useragent(db: &db::DatabasePool) {
+    let mut conn = db.get().await.unwrap();
+    let sentinel_key = MlDsa87::key_gen(&mut rand::rng())
+        .verifying_key()
+        .encode()
+        .to_vec();
+
+    insert_into(schema::useragent_client::table)
+        .values((
+            schema::useragent_client::public_key.eq(sentinel_key),
+            schema::useragent_client::key_type.eq(1i32),
+        ))
        .execute(&mut conn)
        .await
        .unwrap();
 }

+async fn spawn_test_actors(db: &db::DatabasePool) -> GlobalActors {
+    insert_bootstrap_sentinel_useragent(db).await;
+
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    actors
+        .key_holder
+        .ask(Bootstrap {
+            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+        })
+        .await
+        .unwrap();
+    actors
+}
+
 #[tokio::test]
 #[test_log::test]
 pub async fn test_unregistered_pubkey_rejected() {
    let db = db::create_test_pool().await;

    let (server_transport, mut test_transport) = ChannelTransport::new();
-    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let actors = spawn_test_actors(&db).await;
    let props = ClientConnection::new(db.clone(), actors);
    let task = tokio::spawn(async move {
        let mut server_transport = server_transport;
        connect_client(props, &mut server_transport).await;
    });

-    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
+    let new_key = MlDsa87::key_gen(&mut rand::rng());

    test_transport
        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: new_key.verifying_key(),
+            pubkey: new_key.verifying_key().into(),
            metadata: metadata("client", Some("desc"), Some("1.0.0")),
        })
        .await
@@ -78,20 +143,19 @@ pub async fn test_unregistered_pubkey_rejected() {
 #[test_log::test]
 pub async fn test_challenge_auth() {
    let db = db::create_test_pool().await;
+    let actors = spawn_test_actors(&db).await;

-    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-    let pubkey_bytes = new_key.verifying_key().to_bytes().to_vec();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());

    insert_registered_client(
        &db,
-        pubkey_bytes.clone(),
+        &actors,
+        new_key.verifying_key(),
        &metadata("client", Some("desc"), Some("1.0.0")),
    )
    .await;

    let (server_transport, mut test_transport) = ChannelTransport::new();
-    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
-
    let props = ClientConnection::new(db.clone(), actors);
    let task = tokio::spawn(async move {
        let mut server_transport = server_transport;
@@ -101,7 +165,7 @@ pub async fn test_challenge_auth() {
    // Send challenge request
    test_transport
        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: new_key.verifying_key(),
+            pubkey: new_key.verifying_key().into(),
            metadata: metadata("client", Some("desc"), Some("1.0.0")),
        })
        .await
@@ -121,8 +185,7 @@ pub async fn test_challenge_auth() {
    };

    // Sign the challenge and send solution
-    let formatted_challenge = arbiter_proto::format_challenge(challenge.1, challenge.0.as_bytes());
-    let signature = new_key.sign(&formatted_challenge);
+    let signature = sign_client_challenge(&new_key, challenge.1, &challenge.0);

    test_transport
        .send(auth::Inbound::AuthChallengeSolution { signature })
@@ -147,34 +210,13 @@ pub async fn test_challenge_auth() {
 #[test_log::test]
 pub async fn test_metadata_unchanged_does_not_append_history() {
    let db = db::create_test_pool().await;
-    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
-    let props = ClientConnection::new(db.clone(), actors);
-
-    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
+    let actors = spawn_test_actors(&db).await;
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
    let requested = metadata("client", Some("desc"), Some("1.0.0"));

-    {
-        use arbiter_server::db::schema::{client_metadata, program_client};
-        let mut conn = db.get().await.unwrap();
-        let metadata_id: i32 = insert_into(client_metadata::table)
-            .values((
-                client_metadata::name.eq(&requested.name),
-                client_metadata::description.eq(&requested.description),
-                client_metadata::version.eq(&requested.version),
-            ))
-            .returning(client_metadata::id)
-            .get_result(&mut conn)
-            .await
-            .unwrap();
-        insert_into(program_client::table)
-            .values((
-                program_client::public_key.eq(new_key.verifying_key().to_bytes().to_vec()),
-                program_client::metadata_id.eq(metadata_id),
-            ))
-            .execute(&mut conn)
-            .await
-            .unwrap();
-    }
+    insert_registered_client(&db, &actors, new_key.verifying_key(), &requested).await;
+
+    let props = ClientConnection::new(db.clone(), actors);

    let (server_transport, mut test_transport) = ChannelTransport::new();
    let task = tokio::spawn(async move {
@@ -184,7 +226,7 @@ pub async fn test_metadata_unchanged_does_not_append_history() {

    test_transport
        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: new_key.verifying_key(),
+            pubkey: new_key.verifying_key().into(),
            metadata: requested,
        })
        .await
@@ -195,7 +237,7 @@ pub async fn test_metadata_unchanged_does_not_append_history() {
        auth::Outbound::AuthChallenge { pubkey, nonce } => (pubkey, nonce),
        other => panic!("Expected AuthChallenge, got {other:?}"),
    };
-    let signature = new_key.sign(&arbiter_proto::format_challenge(nonce, pubkey.as_bytes()));
+    let signature = sign_client_challenge(&new_key, nonce, &pubkey);
    test_transport
        .send(auth::Inbound::AuthChallengeSolution { signature })
        .await
@@ -225,34 +267,19 @@ pub async fn test_metadata_unchanged_does_not_append_history() {
 #[test_log::test]
 pub async fn test_metadata_change_appends_history_and_repoints_binding() {
    let db = db::create_test_pool().await;
-    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let actors = spawn_test_actors(&db).await;
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
+
+    insert_registered_client(
+        &db,
+        &actors,
+        new_key.verifying_key(),
+        &metadata("client", Some("old"), Some("1.0.0")),
+    )
+    .await;
+
    let props = ClientConnection::new(db.clone(), actors);

-    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-
-    {
-        use arbiter_server::db::schema::{client_metadata, program_client};
-        let mut conn = db.get().await.unwrap();
-        let metadata_id: i32 = insert_into(client_metadata::table)
-            .values((
-                client_metadata::name.eq("client"),
-                client_metadata::description.eq(Some("old")),
-                client_metadata::version.eq(Some("1.0.0")),
-            ))
-            .returning(client_metadata::id)
-            .get_result(&mut conn)
-            .await
-            .unwrap();
-        insert_into(program_client::table)
-            .values((
-                program_client::public_key.eq(new_key.verifying_key().to_bytes().to_vec()),
-                program_client::metadata_id.eq(metadata_id),
-            ))
-            .execute(&mut conn)
-            .await
-            .unwrap();
-    }
-
    let (server_transport, mut test_transport) = ChannelTransport::new();
    let task = tokio::spawn(async move {
        let mut server_transport = server_transport;
@@ -261,7 +288,7 @@ pub async fn test_metadata_change_appends_history_and_repoints_binding() {

    test_transport
        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: new_key.verifying_key(),
+            pubkey: new_key.verifying_key().into(),
            metadata: metadata("client", Some("new"), Some("2.0.0")),
        })
        .await
@@ -272,7 +299,7 @@ pub async fn test_metadata_change_appends_history_and_repoints_binding() {
        auth::Outbound::AuthChallenge { pubkey, nonce } => (pubkey, nonce),
        other => panic!("Expected AuthChallenge, got {other:?}"),
    };
-    let signature = new_key.sign(&arbiter_proto::format_challenge(nonce, pubkey.as_bytes()));
+    let signature = sign_client_challenge(&new_key, nonce, &pubkey);
    test_transport
        .send(auth::Inbound::AuthChallengeSolution { signature })
        .await
@@ -322,3 +349,59 @@ pub async fn test_metadata_change_appends_history_and_repoints_binding() {
        );
    }
 }
+
+#[tokio::test]
+#[test_log::test]
+pub async fn test_challenge_auth_rejects_integrity_tag_mismatch() {
+    let db = db::create_test_pool().await;
+    let actors = spawn_test_actors(&db).await;
+
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
+    let requested = metadata("client", Some("desc"), Some("1.0.0"));
+
+    {
+        use arbiter_server::db::schema::{client_metadata, program_client};
+        let mut conn = db.get().await.unwrap();
+        let metadata_id: i32 = insert_into(client_metadata::table)
+            .values((
+                client_metadata::name.eq(&requested.name),
+                client_metadata::description.eq(&requested.description),
+                client_metadata::version.eq(&requested.version),
+            ))
+            .returning(client_metadata::id)
+            .get_result(&mut conn)
+            .await
+            .unwrap();
+        insert_into(program_client::table)
+            .values((
+                program_client::public_key.eq(new_key.verifying_key().encode().to_vec()),
+                program_client::metadata_id.eq(metadata_id),
+            ))
+            .execute(&mut conn)
+            .await
+            .unwrap();
+    }
+
+    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let props = ClientConnection::new(db.clone(), actors);
+    let task = tokio::spawn(async move {
+        let mut server_transport = server_transport;
+        connect_client(props, &mut server_transport).await;
+    });
+
+    test_transport
+        .send(auth::Inbound::AuthChallengeRequest {
+            pubkey: new_key.verifying_key().into(),
+            metadata: requested,
+        })
+        .await
+        .unwrap();
+
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive auth rejection");
+    assert!(matches!(response, Err(auth::Error::IntegrityCheckFailed)));
+
+    task.await.unwrap();
+}
--- a/server/crates/arbiter-server/tests/common/mod.rs
+++ b/server/crates/arbiter-server/tests/common/mod.rs
@@ -1,9 +1,10 @@
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_proto::transport::{Bi, Error, Receiver, Sender};
 use arbiter_server::{
    actors::keyholder::KeyHolder,
    db::{self, schema},
-    safe_cell::{SafeCell, SafeCellHandle as _},
 };
+
 use async_trait::async_trait;
 use diesel::QueryDsl;
 use diesel_async::RunQueryDsl;
--- a/server/crates/arbiter-server/tests/keyholder/concurrency.rs
+++ b/server/crates/arbiter-server/tests/keyholder/concurrency.rs
@@ -1,10 +1,11 @@
 use std::collections::{HashMap, HashSet};

+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
    actors::keyholder::{CreateNew, Error, KeyHolder},
    db::{self, models, schema},
-    safe_cell::{SafeCell, SafeCellHandle as _},
 };
+
 use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper, dsl::sql_query};
 use diesel_async::RunQueryDsl;
 use kameo::actor::{ActorRef, Spawn as _};
--- a/server/crates/arbiter-server/tests/keyholder/lifecycle.rs
+++ b/server/crates/arbiter-server/tests/keyholder/lifecycle.rs
@@ -1,9 +1,10 @@
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
    actors::keyholder::{Error, KeyHolder},
    crypto::encryption::v1::{Nonce, ROOT_KEY_TAG},
    db::{self, models, schema},
-    safe_cell::{SafeCell, SafeCellHandle as _},
 };
+
 use diesel::{QueryDsl, SelectableHelper};
 use diesel_async::RunQueryDsl;

--- a/server/crates/arbiter-server/tests/keyholder/storage.rs
+++ b/server/crates/arbiter-server/tests/keyholder/storage.rs
@@ -1,11 +1,12 @@
 use std::collections::HashSet;

+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
    actors::keyholder::Error,
    crypto::encryption::v1::Nonce,
    db::{self, models, schema},
-    safe_cell::{SafeCell, SafeCellHandle as _},
 };
+
 use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper, dsl::update};
 use diesel_async::RunQueryDsl;

--- a/server/crates/arbiter-server/tests/user_agent/auth.rs
+++ b/server/crates/arbiter-server/tests/user_agent/auth.rs
@@ -1,25 +1,49 @@
+use arbiter_crypto::{
+    authn::{self, USERAGENT_CONTEXT, format_challenge},
+    safecell::{SafeCell, SafeCellHandle as _},
+};
+
 use arbiter_proto::transport::{Receiver, Sender};
 use arbiter_server::{
    actors::{
        GlobalActors,
        bootstrap::GetToken,
        keyholder::Bootstrap,
-        user_agent::{AuthPublicKey, UserAgentConnection, auth},
+        user_agent::{UserAgentConnection, UserAgentCredentials, auth},
    },
+    crypto::integrity,
    db::{self, schema},
-    safe_cell::{SafeCell, SafeCellHandle as _},
 };
 use diesel::{ExpressionMethods as _, QueryDsl, insert_into};
 use diesel_async::RunQueryDsl;
-use ed25519_dalek::Signer as _;
+use ml_dsa::{KeyGen, MlDsa87, SigningKey, signature::Keypair as _};

 use super::common::ChannelTransport;

+fn sign_useragent_challenge(
+    key: &SigningKey<MlDsa87>,
+    nonce: i32,
+    pubkey_bytes: &[u8],
+) -> authn::Signature {
+    let challenge = format_challenge(nonce, pubkey_bytes);
+    key.signing_key()
+        .sign_deterministic(&challenge, USERAGENT_CONTEXT)
+        .unwrap()
+        .into()
+}
+
 #[tokio::test]
 #[test_log::test]
 pub async fn test_bootstrap_token_auth() {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    actors
+        .key_holder
+        .ask(Bootstrap {
+            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+        })
+        .await
+        .unwrap();
    let token = actors.bootstrapper.ask(GetToken).await.unwrap().unwrap();

    let (server_transport, mut test_transport) = ChannelTransport::new();
@@ -29,10 +53,10 @@ pub async fn test_bootstrap_token_auth() {
        auth::authenticate(&mut props, server_transport).await
    });

-    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
    test_transport
        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+            pubkey: new_key.verifying_key().into(),
            bootstrap_token: Some(token),
        })
        .await
@@ -55,7 +79,7 @@ pub async fn test_bootstrap_token_auth() {
        .first::<Vec<u8>>(&mut conn)
        .await
        .unwrap();
-    assert_eq!(stored_pubkey, new_key.verifying_key().to_bytes().to_vec());
+    assert_eq!(stored_pubkey, new_key.verifying_key().encode().to_vec());
 }

 #[tokio::test]
@@ -71,10 +95,10 @@ pub async fn test_bootstrap_invalid_token_auth() {
        auth::authenticate(&mut props, server_transport).await
    });

-    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
    test_transport
        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+            pubkey: new_key.verifying_key().into(),
            bootstrap_token: Some("invalid_token".to_string()),
        })
        .await
@@ -99,18 +123,37 @@ pub async fn test_bootstrap_invalid_token_auth() {
 pub async fn test_challenge_auth() {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    actors
+        .key_holder
+        .ask(Bootstrap {
+            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+        })
+        .await
+        .unwrap();

-    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-    let pubkey_bytes = new_key.verifying_key().to_bytes().to_vec();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
+    let pubkey_bytes = new_key.verifying_key().encode().to_vec();

    {
        let mut conn = db.get().await.unwrap();
-        insert_into(schema::useragent_client::table)
+        let id: i32 = insert_into(schema::useragent_client::table)
            .values((
                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
                schema::useragent_client::key_type.eq(1i32),
            ))
-            .execute(&mut conn)
+            .returning(schema::useragent_client::id)
+            .get_result(&mut conn)
+            .await
+            .unwrap();
+        integrity::sign_entity(
+            &mut conn,
+            &actors.key_holder,
+            &UserAgentCredentials {
+                pubkey: new_key.verifying_key().into(),
+                nonce: 1,
+            },
+            id,
+        )
        .await
        .unwrap();
    }
@@ -124,7 +167,7 @@ pub async fn test_challenge_auth() {

    test_transport
        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+            pubkey: new_key.verifying_key().into(),
            bootstrap_token: None,
        })
        .await
@@ -142,12 +185,11 @@ pub async fn test_challenge_auth() {
        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
    };

-    let formatted_challenge = arbiter_proto::format_challenge(challenge, &pubkey_bytes);
-    let signature = new_key.sign(&formatted_challenge);
+    let signature = sign_useragent_challenge(&new_key, challenge, &pubkey_bytes);

    test_transport
        .send(auth::Inbound::AuthChallengeSolution {
-            signature: signature.to_bytes().to_vec(),
+            signature: signature.to_bytes(),
        })
        .await
        .unwrap();
@@ -178,8 +220,8 @@ pub async fn test_challenge_auth_rejects_integrity_tag_mismatch_when_unsealed()
        .await
        .unwrap();

-    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-    let pubkey_bytes = new_key.verifying_key().to_bytes().to_vec();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
+    let pubkey_bytes = new_key.verifying_key().encode().to_vec();

    {
        let mut conn = db.get().await.unwrap();
@@ -187,7 +229,6 @@ pub async fn test_challenge_auth_rejects_integrity_tag_mismatch_when_unsealed()
            .values((
                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
                schema::useragent_client::key_type.eq(1i32),
-                schema::useragent_client::pubkey_integrity_tag.eq(Some(vec![0u8; 32])),
            ))
            .execute(&mut conn)
            .await
@@ -203,7 +244,7 @@ pub async fn test_challenge_auth_rejects_integrity_tag_mismatch_when_unsealed()

    test_transport
        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+            pubkey: new_key.verifying_key().into(),
            bootstrap_token: None,
        })
        .await
@@ -211,7 +252,7 @@ pub async fn test_challenge_auth_rejects_integrity_tag_mismatch_when_unsealed()

    assert!(matches!(
        task.await.unwrap(),
-        Err(auth::Error::InvalidChallengeSolution)
+        Err(auth::Error::Internal { .. })
    ));
 }

@@ -220,18 +261,37 @@ pub async fn test_challenge_auth_rejects_integrity_tag_mismatch_when_unsealed()
 pub async fn test_challenge_auth_rejects_invalid_signature() {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    actors
+        .key_holder
+        .ask(Bootstrap {
+            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+        })
+        .await
+        .unwrap();

-    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-    let pubkey_bytes = new_key.verifying_key().to_bytes().to_vec();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
+    let pubkey_bytes = new_key.verifying_key().encode().to_vec();

    {
        let mut conn = db.get().await.unwrap();
-        insert_into(schema::useragent_client::table)
+        let id: i32 = insert_into(schema::useragent_client::table)
            .values((
                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
                schema::useragent_client::key_type.eq(1i32),
            ))
-            .execute(&mut conn)
+            .returning(schema::useragent_client::id)
+            .get_result(&mut conn)
+            .await
+            .unwrap();
+        integrity::sign_entity(
+            &mut conn,
+            &actors.key_holder,
+            &UserAgentCredentials {
+                pubkey: new_key.verifying_key().into(),
+                nonce: 1,
+            },
+            id,
+        )
        .await
        .unwrap();
    }
@@ -245,7 +305,7 @@ pub async fn test_challenge_auth_rejects_invalid_signature() {

    test_transport
        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+            pubkey: new_key.verifying_key().into(),
            bootstrap_token: None,
        })
        .await
@@ -263,12 +323,11 @@ pub async fn test_challenge_auth_rejects_invalid_signature() {
        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
    };

-    let wrong_challenge = arbiter_proto::format_challenge(challenge + 1, &pubkey_bytes);
-    let signature = new_key.sign(&wrong_challenge);
+    let signature = sign_useragent_challenge(&new_key, challenge + 1, &pubkey_bytes);

    test_transport
        .send(auth::Inbound::AuthChallengeSolution {
-            signature: signature.to_bytes().to_vec(),
+            signature: signature.to_bytes(),
        })
        .await
        .unwrap();
--- a/server/crates/arbiter-server/tests/user_agent/unseal.rs
+++ b/server/crates/arbiter-server/tests/user_agent/unseal.rs
@@ -1,3 +1,4 @@
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
    actors::{
        GlobalActors,
@@ -8,11 +9,9 @@ use arbiter_server::{
        },
    },
    db,
-    safe_cell::{SafeCell, SafeCellHandle as _},
 };
+
 use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
-use diesel::{ExpressionMethods as _, QueryDsl as _, insert_into};
-use diesel_async::RunQueryDsl;
 use kameo::actor::Spawn as _;
 use x25519_dalek::{EphemeralSecret, PublicKey};

@@ -152,42 +151,3 @@ pub async fn test_unseal_retry_after_invalid_key() {
        assert!(matches!(response, Ok(())));
    }
 }
-
-#[tokio::test]
-#[test_log::test]
-pub async fn test_unseal_backfills_missing_pubkey_integrity_tags() {
-    let seal_key = b"test-seal-key";
-    let (db, user_agent) = setup_sealed_user_agent(seal_key).await;
-
-    {
-        let mut conn = db.get().await.unwrap();
-        insert_into(arbiter_server::db::schema::useragent_client::table)
-            .values((
-                arbiter_server::db::schema::useragent_client::public_key
-                    .eq(vec![1u8, 2u8, 3u8, 4u8]),
-                arbiter_server::db::schema::useragent_client::key_type.eq(1i32),
-                arbiter_server::db::schema::useragent_client::pubkey_integrity_tag
-                    .eq(Option::<Vec<u8>>::None),
-            ))
-            .execute(&mut conn)
-            .await
-            .unwrap();
-    }
-
-    let encrypted_key = client_dh_encrypt(&user_agent, seal_key).await;
-    let response = user_agent.ask(encrypted_key).await;
-    assert!(matches!(response, Ok(())));
-
-    {
-        let mut conn = db.get().await.unwrap();
-        let tags: Vec<Option<Vec<u8>>> = arbiter_server::db::schema::useragent_client::table
-            .select(arbiter_server::db::schema::useragent_client::pubkey_integrity_tag)
-            .load(&mut conn)
-            .await
-            .unwrap();
-        assert!(
-            tags.iter()
-                .all(|tag| matches!(tag, Some(v) if v.len() == 32))
-        );
-    }
-}
Author	SHA1	Message	Date
Stas	62dff3f810	Merge pull request 'refactor(hashing): introduce Hashable derive macro and migrate server types' (#82 ) from hashing-proc-macro into main Some checks failed ci/woodpecker/push/server-audit Pipeline was successful Details ci/woodpecker/push/server-lint Pipeline was successful Details ci/woodpecker/push/server-vet Pipeline failed Details ci/woodpecker/push/server-test Pipeline was successful Details Reviewed-on: #82 Reviewed-by: Stas <business@jexter.tech>	2026-04-08 00:18:40 +00:00
CleverWild	6e22f368c9	refactor(hashing): introduce Hashable derive macro and migrate server types Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-lint Pipeline was successful Details ci/woodpecker/pr/server-test Pipeline was successful Details	2026-04-08 01:32:59 +02:00
Stas	f3cf6a9438	Merge pull request 'Post-quantum crypto and better useragent security' (#80 ) from push-xrxykvkuxpsv into main Some checks failed ci/woodpecker/push/server-audit Pipeline was successful Details ci/woodpecker/push/server-lint Pipeline failed Details ci/woodpecker/push/server-vet Pipeline failed Details ci/woodpecker/push/server-test Pipeline was successful Details Reviewed-on: #80	2026-04-07 19:26:54 +00:00
hdbg	a9f9fc2a9d	housekeeping(server): fixed clippy warns Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-test Pipeline was successful Details	2026-04-07 16:28:47 +02:00
hdbg	d22ab49e3d	refactor(server): moved shared module crypto into `arbiter-crypto`	2026-04-07 16:24:51 +02:00
hdbg	a845181ef6	docs: ml-dsa scheme everywhere Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-test Pipeline was successful Details	2026-04-07 15:02:32 +02:00
hdbg	0d424f3afc	refactor(server): migrated auth to `ml-dsa`	2026-04-07 14:55:31 +02:00
hdbg	1497884ce6	fix(server::bootsrapper): token compare is now constant-time Some checks failed ci/woodpecker/push/server-audit Pipeline was successful Details ci/woodpecker/push/server-vet Pipeline failed Details ci/woodpecker/push/server-lint Pipeline failed Details ci/woodpecker/push/server-test Pipeline was successful Details	2026-04-06 18:33:47 +02:00
hdbg	b3464cf8a6	tests(server::client::auth): integrity envelope insertion for valid paths Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-test Pipeline was successful Details ci/woodpecker/push/server-audit Pipeline was successful Details ci/woodpecker/push/server-vet Pipeline failed Details ci/woodpecker/push/server-lint Pipeline failed Details ci/woodpecker/push/server-test Pipeline was successful Details	2026-04-06 18:24:13 +02:00
hdbg	46d1318b6f	feat(server): add integrity verification for client keys	2026-04-06 18:13:11 +02:00
Stas	9c80d51d45	Merge pull request 'fix(server): replaced postcard-based integrity fingerprint with custom trait providing order-independent hashing' (#77 ) from push-opwuyuwxknyo into main Some checks failed ci/woodpecker/push/server-audit Pipeline was successful Details ci/woodpecker/push/server-vet Pipeline failed Details ci/woodpecker/push/server-lint Pipeline failed Details ci/woodpecker/push/server-test Pipeline was successful Details Reviewed-on: #77	2026-04-06 15:42:47 +00:00
hdbg	33456a644d	tests(server): property-based testing for ordering independency for hash Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-test Pipeline was successful Details	2026-04-06 17:40:41 +02:00
hdbg	5bc0c42cc7	fix(server): replaced `postcard`-based integrity fingerprint with custom trait providing order-independent hashing	2026-04-06 16:25:32 +02:00
hdbg	f6b62ab884	fix(server): added `chain_id` check and covered `check_shared_constraints` with unit tests Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-test Pipeline was successful Details ci/woodpecker/push/server-audit Pipeline was successful Details ci/woodpecker/push/server-lint Pipeline failed Details ci/woodpecker/push/server-vet Pipeline failed Details ci/woodpecker/push/server-test Pipeline was successful Details	2026-04-06 12:57:18 +02:00
hdbg	2dd5a3f32f	tests(server): initial `cargo-mutants` Some checks failed ci/woodpecker/push/server-audit Pipeline was successful Details ci/woodpecker/push/server-vet Pipeline failed Details ci/woodpecker/push/server-lint Pipeline failed Details ci/woodpecker/push/server-test Pipeline was successful Details	2026-04-06 12:03:56 +02:00
hdbg	1aca9d4007	fix(server): simplify hash function for `debug` profile	2026-04-05 22:50:28 +02:00
Stas	5ee1b49c43	Merge pull request 'feat(server): integrity envelope engine for EVM grants with HMAC verification' (#51 ) from integrity-envelope into main Some checks failed ci/woodpecker/push/server-audit Pipeline was successful Details ci/woodpecker/push/server-lint Pipeline failed Details ci/woodpecker/push/server-vet Pipeline failed Details ci/woodpecker/push/server-test Pipeline was successful Details Reviewed-on: #51	2026-04-05 16:26:51 +00:00
hdbg	00745bb381	tests(server): fixed for new integrity checks Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-test Pipeline was successful Details	2026-04-05 14:49:02 +02:00
hdbg	b122aa464c	refactor(server): rework envelopes and integrity check Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-test Pipeline failed Details	2026-04-05 14:17:00 +02:00
hdbg	9fab945a00	fix(server): remove stale mentions of miette Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-test Pipeline failed Details ci/woodpecker/pr/server-vet Pipeline failed Details	2026-04-05 10:45:24 +02:00
CleverWild	aeed664e9a	chore: inline integrity proto types Some checks failed ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-test Pipeline failed Details ci/woodpecker/pr/server-vet Pipeline failed Details	2026-04-05 10:44:21 +02:00
CleverWild	4057c1fc12	feat(server): integrity envelope engine for EVM grants with HMAC verification	2026-04-05 10:44:21 +02:00
hdbg	f5eb51978d	docs: add recovery operators and multi-operator details	2026-04-05 08:27:24 +00:00
hdbg	d997e0f843	docs: add multi-operator governance section	2026-04-05 08:27:24 +00:00