Merge pull request 'Post-quantum crypto and better useragent security' (#80 ) from push-xrxykvkuxpsv into main

Reviewed-on: #80
housekeeping(server): fixed clippy warns
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 · 2026-04-07 14:55:31 +02:00 · 2026-04-06 18:33:47 +02:00
60 changed files with 1568 additions and 812 deletions
--- 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**
--- 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 +692,16 @@ dependencies = [
 "tonic",
 ]

+[[package]]
+name = "arbiter-crypto"
+version = "0.1.0"
+dependencies = [
+ "base64",
+ "memsafe",
+ "ml-dsa",
+ "rand 0.10.0",
+]
+
 [[package]]
 name = "arbiter-proto"
 version = "0.1.0"
@@ -725,6 +735,7 @@ version = "0.1.0"
 dependencies = [
 "alloy",
 "anyhow",
+ "arbiter-crypto",
 "arbiter-proto",
 "arbiter-tokens-registry",
 "argon2",
@@ -742,23 +753,24 @@ dependencies = [
 "insta",
 "k256",
 "kameo",
- "memsafe",
+ "ml-dsa",
+ "mutants",
 "pem",
- "postcard",
+ "proptest",
 "prost",
 "prost-types",
 "rand 0.10.0",
 "rcgen",
 "restructed",
- "rsa",
+ "rstest",
 "rustls",
 "secrecy",
- "serde",
 "serde_with",
 "sha2 0.10.9",
 "smlang",
- "spki",
+ "spki 0.7.3",
 "strum 0.28.0",
+ "subtle",
 "test-log",
 "thiserror 2.0.18",
 "tokio",
@@ -1057,15 +1069,6 @@ dependencies = [
 "syn 2.0.117",
 ]

-[[package]]
-name = "atomic-polyfill"
-version = "1.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8cf2bce30dfe09ef0bfaef228b9d414faaf7e563035494d7fe092dba54b300f4"
-dependencies = [
- "critical-section",
-]
-
 [[package]]
 name = "atomic-waker"
 version = "1.1.2"
@@ -1457,13 +1460,10 @@ dependencies = [
 ]

 [[package]]
-name = "cobs"
-version = "0.3.0"
+name = "cmov"
+version = "0.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0fa961b519f0b462e3a3b4a34b64d119eeaca1d59af726fe450bbba07a9fc0a1"
-dependencies = [
- "thiserror 2.0.18",
-]
+checksum = "3f88a43d011fc4a6876cb7344703e297c71dda42494fee094d5f7c76bf13f746"

 [[package]]
 name = "console"
@@ -1495,6 +1495,12 @@ 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"
@@ -1572,12 +1578,6 @@ dependencies = [
 "cfg-if",
 ]

-[[package]]
-name = "critical-section"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "790eea4361631c5e7d22598ecd5723ff611904e3344ce8720784c93e3d83d40b"
-
 [[package]]
 name = "crossbeam-utils"
 version = "0.8.21"
@@ -1622,6 +1622,15 @@ 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"
@@ -1760,8 +1769,17 @@ 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",
 ]

@@ -1904,7 +1922,7 @@ 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",
 ]
@@ -1968,13 +1986,13 @@ 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]]
@@ -1983,7 +2001,6 @@ version = "3.0.0-rc.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c6e914c7c52decb085cea910552e24c63ac019e3ab8bf001ff736da9a9d9d890"
 dependencies = [
- "serde",
 "signature 3.0.0-rc.10",
 ]

@@ -1996,7 +2013,6 @@ dependencies = [
 "curve25519-dalek 5.0.0-pre.6",
 "ed25519",
 "rand_core 0.10.0",
- "serde",
 "sha2 0.11.0-rc.5",
 "subtle",
 "zeroize",
@@ -2035,7 +2051,7 @@ dependencies = [
 "ff",
 "generic-array",
 "group",
- "pkcs8",
+ "pkcs8 0.10.2",
 "rand_core 0.6.4",
 "sec1",
 "serdect",
@@ -2043,18 +2059,6 @@ dependencies = [
 "zeroize",
 ]

-[[package]]
-name = "embedded-io"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ef1a6892d9eef45c8fa6b9e0086428a2cca8491aca8f787c534a3d6d0bcb3ced"
-
-[[package]]
-name = "embedded-io"
-version = "0.6.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "edd0f118536f44f5ccd48bcb8b111bdc3de888b58c74639dfb034a357d0f206d"
-
 [[package]]
 name = "encode_unicode"
 version = "1.0.0"
@@ -2472,15 +2476,6 @@ dependencies = [
 "tracing",
 ]

-[[package]]
-name = "hash32"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b0c35f58762feb77d74ebe43bdbc3210f09be9fe6742234d573bacc26ed92b67"
-dependencies = [
- "byteorder",
-]
-
 [[package]]
 name = "hashbrown"
 version = "0.12.3"
@@ -2515,20 +2510,6 @@ dependencies = [
 "serde_core",
 ]

-[[package]]
-name = "heapless"
-version = "0.7.17"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cdc6457c0eb62c71aac4bc17216026d8410337c4126773b9c5daba343f17964f"
-dependencies = [
- "atomic-polyfill",
- "hash32",
- "rustc_version 0.4.1",
- "serde",
- "spin",
- "stable_deref_trait",
-]
-
 [[package]]
 name = "heck"
 version = "0.5.0"
@@ -2617,6 +2598,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8655f91cd07f2b9d0c24137bd650fe69617773435ee5ec83022377777ce65ef1"
 dependencies = [
 "typenum",
+ "zeroize",
 ]

 [[package]]
@@ -3014,6 +2996,16 @@ 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"
@@ -3029,9 +3021,6 @@ name = "lazy_static"
 version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
-dependencies = [
- "spin",
-]

 [[package]]
 name = "leb128fmt"
@@ -3230,12 +3219,46 @@ 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"
@@ -3265,23 +3288,6 @@ 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",
- "serde",
- "smallvec",
- "zeroize",
-]
-
 [[package]]
 name = "num-conv"
 version = "0.2.0"
@@ -3297,17 +3303,6 @@ 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"
@@ -3477,15 +3472,6 @@ 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"
@@ -3545,25 +3531,24 @@ 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]]
@@ -3589,19 +3574,6 @@ version = "1.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c33a9471896f1c69cecef8d20cbe2f7accd12527ce60845ff44c153bb2a21b49"

-[[package]]
-name = "postcard"
-version = "1.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6764c3b5dd454e283a30e6dfe78e9b31096d9e32036b5d1eaac7a6119ccb9a24"
-dependencies = [
- "cobs",
- "embedded-io 0.4.0",
- "embedded-io 0.6.1",
- "heapless",
- "serde",
-]
-
 [[package]]
 name = "potential_utf"
 version = "0.1.4"
@@ -3713,9 +3685,9 @@ 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",
@@ -4216,28 +4188,6 @@ 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",
- "serde",
- "sha2 0.10.9",
- "signature 2.2.0",
- "spki",
- "subtle",
- "zeroize",
-]
-
 [[package]]
 name = "rsqlite-vfs"
 version = "0.1.0"
@@ -4477,9 +4427,9 @@ 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",
@@ -4673,7 +4623,17 @@ 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]]
@@ -4726,6 +4686,10 @@ 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"
@@ -4785,15 +4749,6 @@ dependencies = [
 "windows-sys 0.61.2",
 ]

-[[package]]
-name = "spin"
-version = "0.9.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
-dependencies = [
- "lock_api",
-]
-
 [[package]]
 name = "spki"
 version = "0.7.3"
@@ -4801,7 +4756,17 @@ 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]]
--- 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"
@@ -44,3 +44,6 @@ 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"
--- 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 +1,18 @@
+[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}
+
+[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 +1,186 @@
+use base64::{Engine as _, prelude::BASE64_STANDARD};
+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>>);
+
+#[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().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().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/lib.rs
+++ b/server/crates/arbiter-crypto/src/lib.rs
@@ -0,0 +1,5 @@
+#[cfg(feature = "authn")]
+pub mod authn;
+
+#[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-proto/Cargo.toml
+++ b/server/crates/arbiter-proto/Cargo.toml
@@ -17,7 +17,7 @@ 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
@@ -16,9 +16,8 @@ diesel-async = { version = "0.8.0", features = [
    "sqlite",
    "tokio",
 ] }
-ed25519-dalek.workspace = true
-ed25519-dalek.features = ["serde"]
 arbiter-proto.path = "../arbiter-proto"
+arbiter-crypto.path = "../arbiter-crypto"
 tracing.workspace = true
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 tonic.workspace = true
@@ -37,19 +36,13 @@ 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
-k256.features = ["serde"]
-rsa.workspace = true
-rsa.features = ["serde"]
 sha2.workspace = true
 hmac = "0.12"
 spki.workspace = true
@@ -58,10 +51,16 @@ prost-types.workspace = true
 prost.workspace = true
 arbiter-tokens-registry.path = "../arbiter-tokens-registry"
 anyhow = "1.0.102"
-postcard = { version = "1.1.3", features = ["use-std"] }
-serde = { version = "1.0.228", features = ["derive"] }
 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
@@ -47,7 +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,
-    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;
--- 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 mut conn = db.get().await?;
+        let row_count: i64 = {
+            let mut conn = db.get().await?;

-        let row_count: i64 = schema::useragent_client::table
-            .count()
-            .get_result(&mut conn)
-            .await?;
-
-        drop(conn);
+            schema::useragent_client::table
+                .count()
+                .get_result(&mut 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(
@@ -139,45 +212,65 @@ 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
    })?;

-    let metadata_id = insert_into(client_metadata::table)
-        .values((
-            client_metadata::name.eq(&metadata.name),
-            client_metadata::description.eq(&metadata.description),
-            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
-        })?;
+    conn.exclusive_transaction(|conn| {
+        let keyholder = keyholder.clone();
+        let pubkey = pubkey.clone();
+        Box::pin(async move {
+            const NONCE_START: i32 = 1;

-    let client_id = insert_into(program_client::table)
-        .values((
-            program_client::public_key.eq(pubkey.as_bytes().to_vec()),
-            program_client::metadata_id.eq(metadata_id),
-            program_client::nonce.eq(1), // pre-incremented; challenge uses 0
-        ))
-        .on_conflict_do_nothing()
-        .returning(program_client::id)
-        .get_result::<i32>(&mut conn)
-        .await
-        .map_err(|e| {
-            error!(error = ?e, "Failed to insert client metadata");
-            Error::DatabaseOperationFailed
-        })?;
+            let metadata_id = insert_into(client_metadata::table)
+                .values((
+                    client_metadata::name.eq(&metadata.name),
+                    client_metadata::description.eq(&metadata.description),
+                    client_metadata::version.eq(&metadata.version),
+                ))
+                .returning(client_metadata::id)
+                .get_result::<i32>(conn)
+                .await?;

-    Ok(client_id)
+            let client_id = insert_into(program_client::table)
+                .values((
+                    program_client::public_key.eq(pubkey.to_bytes()),
+                    program_client::metadata_id.eq(metadata_id),
+                    program_client::nonce.eq(NONCE_START),
+                ))
+                .on_conflict_do_nothing()
+                .returning(program_client::id)
+                .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 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 +1,36 @@
+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, hashing::Hashable},
    db,
 };

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

+pub struct ClientCredentials {
+    pub pubkey: authn::PublicKey,
+    pub nonce: i32,
+}
+
+impl Integrable for ClientCredentials {
+    const KIND: &'static str = "client_credentials";
+}
+
+impl Hashable for ClientCredentials {
+    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
+        hasher.update(self.pubkey.to_bytes());
+        self.nonce.hash(hasher);
+    }
+}
+
 pub struct ClientConnection {
    pub(crate) db: db::DatabasePool,
    pub(crate) actors: GlobalActors,
@@ -31,7 +49,9 @@ 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
@@ -7,21 +7,22 @@ use kameo::{Actor, actor::ActorRef, messages};
 use rand::{SeedableRng, rng, rngs::StdRng};

 use crate::{
-    actors::keyholder::{CreateNew, Decrypt, GetState, KeyHolder, KeyHolderState},
+    actors::keyholder::{CreateNew, Decrypt, KeyHolder},
    crypto::integrity,
    db::{
        DatabaseError, DatabasePool,
-        models::{self, SqliteTimestamp},
+        models::{self},
        schema,
    },
    evm::{
-        self, ListError, RunKind, policies::{
+        self, ListError, RunKind,
+        policies::{
            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;

@@ -157,7 +158,7 @@ impl EvmActor {
    }

    #[message]
-    pub async fn useragent_delete_grant(&mut self, grant_id: i32) -> Result<(), Error> {
+    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();

--- a/server/crates/arbiter-server/src/actors/keyholder/mod.rs
+++ b/server/crates/arbiter-server/src/actors/keyholder/mod.rs
@@ -9,22 +9,17 @@ use kameo::{Actor, Reply, messages};
 use strum::{EnumDiscriminants, IntoDiscriminant};
 use tracing::{error, info};

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

 #[derive(Default, EnumDiscriminants)]
 #[strum_discriminants(derive(Reply), vis(pub), name(KeyHolderState))]
@@ -400,10 +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 {
@@ -71,7 +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
@@ -1,7 +1,8 @@
+use arbiter_crypto::authn::{self, USERAGENT_CONTEXT};
 use arbiter_proto::transport::Bi;
 use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, update};
 use diesel_async::{AsyncConnection, RunQueryDsl};
-use kameo::{actor::ActorRef, error::SendError};
+use kameo::actor::ActorRef;
 use tracing::error;

 use super::Error;
@@ -9,24 +10,24 @@ use crate::{
    actors::{
        bootstrap::ConsumeToken,
        keyholder::KeyHolder,
-        user_agent::{AuthPublicKey, UserAgentConnection, UserAgentCredentials, auth::Outbound},
+        user_agent::{UserAgentConnection, UserAgentCredentials, auth::Outbound},
    },
-    crypto::integrity::{self, AttestationStatus},
+    crypto::integrity,
    db::{DatabasePool, schema::useragent_client},
 };

 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 {
@@ -38,15 +39,15 @@ 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),
    }
 );

 /// Returns the current nonce, ready to use for the challenge nonce.
 async fn get_current_nonce_and_id(
    db: &DatabasePool,
-    key: &AuthPublicKey,
+    key: &authn::PublicKey,
 ) -> Result<(i32, i32), Error> {
    let mut db_conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
@@ -56,8 +57,7 @@ async fn get_current_nonce_and_id(
        .exclusive_transaction(|conn| {
            Box::pin(async move {
                useragent_client::table
-                    .filter(useragent_client::public_key.eq(key.to_stored_bytes()))
-                    .filter(useragent_client::key_type.eq(key.key_type()))
+                    .filter(useragent_client::public_key.eq(key.to_bytes()))
                    .select((useragent_client::id, useragent_client::nonce))
                    .first::<(i32, i32)>(conn)
                    .await
@@ -78,7 +78,7 @@ async fn get_current_nonce_and_id(
 async fn verify_integrity(
    db: &DatabasePool,
    keyholder: &ActorRef<KeyHolder>,
-    pubkey: &AuthPublicKey,
+    pubkey: &authn::PublicKey,
 ) -> Result<(), Error> {
    let mut db_conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
@@ -87,7 +87,7 @@ async fn verify_integrity(

    let (id, nonce) = get_current_nonce_and_id(db, pubkey).await?;

-    let result = integrity::verify_entity(
+    let _result = integrity::verify_entity(
        &mut db_conn,
        keyholder,
        &UserAgentCredentials {
@@ -103,13 +103,12 @@ async fn verify_integrity(
    })?;

    Ok(())
-
 }

 async fn create_nonce(
    db: &DatabasePool,
    keyholder: &ActorRef<KeyHolder>,
-    pubkey: &AuthPublicKey,
+    pubkey: &authn::PublicKey,
 ) -> Result<i32, Error> {
    let mut db_conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
@@ -119,8 +118,7 @@ async fn create_nonce(
        .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_stored_bytes()))
-                    .filter(useragent_client::key_type.eq(pubkey.key_type()))
+                    .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)
@@ -155,10 +153,9 @@ async fn create_nonce(
 async fn register_key(
    db: &DatabasePool,
    keyholder: &ActorRef<KeyHolder>,
-    pubkey: &AuthPublicKey,
+    pubkey: &authn::PublicKey,
 ) -> Result<(), Error> {
-    let pubkey_bytes = pubkey.to_stored_bytes();
-    let key_type = pubkey.key_type();
+    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")
@@ -172,7 +169,6 @@ async fn register_key(
                .values((
                    useragent_client::public_key.eq(pubkey_bytes),
                    useragent_client::nonce.eq(NONCE_START),
-                    useragent_client::key_type.eq(key_type),
                ))
                .returning(useragent_client::id)
                .get_result(conn)
@@ -187,7 +183,7 @@ async fn register_key(
                nonce: NONCE_START,
            };

-            integrity::sign_entity(conn, &keyholder, &entity, id)
+            integrity::sign_entity(conn, keyholder, &entity, id)
                .await
                .map_err(|e| {
                    error!(error = ?e, "Failed to sign integrity tag for new user-agent key");
@@ -246,7 +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
@@ -294,35 +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 => {
--- a/server/crates/arbiter-server/src/actors/user_agent/mod.rs
+++ b/server/crates/arbiter-server/src/actors/user_agent/mod.rs
@@ -1,126 +1,25 @@
 use crate::{
-    actors::{GlobalActors, client::ClientProfile}, crypto::integrity::Integrable, db::{self, models::KeyType}
+    actors::{GlobalActors, client::ClientProfile},
+    crypto::integrity::Integrable,
+    db,
 };
+use arbiter_crypto::authn;

-fn serialize_ecdsa<S>(key: &k256::ecdsa::VerifyingKey, serializer: S) -> Result<S::Ok, S::Error>
-where
-    S: serde::Serializer,
-{
-    // Serialize as hex string for easier debugging (33 bytes compressed SEC1 format)
-    let key = key.to_encoded_point(true);
-    let bytes = key.as_bytes();
-    serializer.serialize_bytes(bytes)
-}
-
-fn deserialize_ecdsa<'de, D>(deserializer: D) -> Result<k256::ecdsa::VerifyingKey, D::Error>
-where
-    D: serde::Deserializer<'de>,
-{
-    struct EcdsaVisitor;
-
-    impl<'de> serde::de::Visitor<'de> for EcdsaVisitor {
-        type Value = k256::ecdsa::VerifyingKey;
-
-        fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
-            formatter.write_str("a compressed SEC1-encoded ECDSA public key")
-        }
-
-        fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
-        where
-            E: serde::de::Error,
-        {
-            let point = k256::EncodedPoint::from_bytes(v)
-                .map_err(|_| E::custom("invalid compressed SEC1 format"))?;
-            k256::ecdsa::VerifyingKey::from_encoded_point(&point)
-                .map_err(|_| E::custom("invalid ECDSA public key"))
-        }
-    }
-
-    deserializer.deserialize_bytes(EcdsaVisitor)
-}
-
-/// Abstraction over Ed25519 / ECDSA-secp256k1 / RSA public keys used during the auth handshake.
-#[derive(Clone, Debug, Serialize)]
-pub enum AuthPublicKey {
-    Ed25519(ed25519_dalek::VerifyingKey),
-    /// Compressed SEC1 public key; signature bytes are raw 64-byte (r||s).
-    #[serde(serialize_with = "serialize_ecdsa", deserialize_with = "deserialize_ecdsa")]
-    EcdsaSecp256k1(k256::ecdsa::VerifyingKey),
-    /// RSA-2048+ public key (Windows Hello / KeyCredentialManager); signature bytes are PSS+SHA-256.
-    Rsa(rsa::RsaPublicKey),
-}
-
-#[derive(Debug, Serialize)]
+#[derive(Debug)]
 pub struct UserAgentCredentials {
-    pub pubkey: AuthPublicKey,
-    pub nonce: i32
+    pub pubkey: authn::PublicKey,
+    pub nonce: i32,
 }

 impl Integrable for UserAgentCredentials {
    const KIND: &'static str = "useragent_credentials";
 }

-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))
-            }
-        }
-    }
-}
-
 // 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 {
@@ -138,5 +37,19 @@ pub mod auth;
 pub mod session;

 pub use auth::authenticate;
-use serde::Serialize;
 pub use session::UserAgentSession;
+
+use crate::crypto::integrity::hashing::Hashable;
+
+impl Hashable for authn::PublicKey {
+    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
+        hasher.update(self.to_bytes());
+    }
+}
+
+impl Hashable for UserAgentCredentials {
+    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
+        self.pubkey.hash(hasher);
+        self.nonce.hash(hasher);
+    }
+}
--- 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::actors::{
+    evm::{
+        ClientSignTransaction, Generate, ListWallets, SignTransactionError as EvmSignError,
+        UseragentCreateGrant, UseragentListGrants,
+    },
+    keyholder::{self, Bootstrap, TryUnseal},
+    user_agent::session::{
+        UserAgentSession,
+        state::{UnsealContext, UserAgentEvents, UserAgentStates},
+    },
+};
 use crate::db::models::{
    EvmWalletAccess, NewEvmWalletAccess, ProgramClient, ProgramClientMetadata,
 };
 use crate::evm::policies::{Grant, SpecificGrant};
-use crate::safe_cell::SafeCell;
-use crate::{
-    actors::{
-        evm::{
-            ClientSignTransaction, Generate, ListWallets, SignTransactionError as EvmSignError,
-            UseragentCreateGrant, UseragentDeleteGrant, UseragentListGrants,
-        },
-        keyholder::{self, Bootstrap, TryUnseal},
-        user_agent::session::{
-            UserAgentSession,
-            state::{UnsealContext, UserAgentEvents, UserAgentStates},
-        },
-    },
-    safe_cell::SafeCellHandle as _,
-};

 impl UserAgentSession {
    fn take_unseal_secret(&mut self) -> Result<(EphemeralSecret, PublicKey), Error> {
@@ -361,19 +361,21 @@ impl UserAgentSession {
        &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)
-            }
-        }
+        // 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]
@@ -473,10 +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
@@ -1,3 +1,3 @@
 pub mod v1;

-pub use 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
@@ -1,3 +1,3 @@
 pub mod v1;

-pub use v1::*;
+pub use v1::*;
--- a/server/crates/arbiter-server/src/crypto/integrity/v1.rs
+++ b/server/crates/arbiter-server/src/crypto/integrity/v1.rs
@@ -1,7 +1,6 @@
-use crate::{actors::keyholder, crypto::KeyCell,safe_cell::SafeCellHandle as _};
-use chacha20poly1305::Key;
+use crate::{actors::keyholder, crypto::integrity::hashing::Hashable};
+use arbiter_crypto::safecell::SafeCellHandle as _;
 use hmac::{Hmac, Mac as _};
-use serde::Serialize;
 use sha2::Sha256;

 use diesel::{ExpressionMethods as _, QueryDsl, dsl::insert_into, sqlite::Sqlite};
@@ -9,6 +8,8 @@ use diesel_async::{AsyncConnection, RunQueryDsl};
 use kameo::{actor::ActorRef, error::SendError};
 use sha2::Digest as _;

+pub mod hashing;
+
 use crate::{
    actors::keyholder::{KeyHolder, SignIntegrity, VerifyIntegrity},
    db::{
@@ -43,9 +44,6 @@ pub enum Error {

    #[error("Integrity MAC mismatch for entity {entity_kind}")]
    MacMismatch { entity_kind: &'static str },
-
-    #[error("Payload serialization error: {0}")]
-    PayloadSerialization(#[from] postcard::Error),
 }

 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -59,13 +57,15 @@ pub const INTEGRITY_SUBKEY_TAG: &[u8] = b"arbiter/db-integrity-key/v1";

 pub type HmacSha256 = Hmac<Sha256>;

-pub trait Integrable: Serialize {
+pub trait Integrable: Hashable {
    const KIND: &'static str;
    const VERSION: i32 = 1;
 }

-fn payload_hash(payload: &[u8]) -> [u8; 32] {
-    Sha256::digest(payload).into()
+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]) {
@@ -109,8 +109,7 @@ pub async fn sign_entity<E: Integrable>(
    entity: &E,
    entity_id: impl IntoId,
 ) -> Result<(), Error> {
-    let payload = postcard::to_stdvec(entity)?;
-    let payload_hash = payload_hash(&payload);
+    let payload_hash = payload_hash(&entity);

    let entity_id = entity_id.into_id();

@@ -127,8 +126,8 @@ pub async fn sign_entity<E: Integrable>(
    insert_into(integrity_envelope::table)
        .values(NewIntegrityEnvelope {
            entity_kind: E::KIND.to_owned(),
-            entity_id: entity_id,
-            payload_version: E::VERSION ,
+            entity_id,
+            payload_version: E::VERSION,
            key_version,
            mac: mac.to_vec(),
        })
@@ -162,7 +161,9 @@ pub async fn verify_entity<E: Integrable>(
        .first(conn)
        .await
        .map_err(|err| match err {
-            diesel::result::Error::NotFound => Error::MissingEnvelope { entity_kind: E::KIND },
+            diesel::result::Error::NotFound => Error::MissingEnvelope {
+                entity_kind: E::KIND,
+            },
            other => Error::Database(db::DatabaseError::from(other)),
        })?;

@@ -174,14 +175,8 @@ pub async fn verify_entity<E: Integrable>(
        });
    }

-    let payload = postcard::to_stdvec(entity)?;
-    let payload_hash = payload_hash(&payload);
-    let mac_input = build_mac_input(
-        E::KIND,
-        &entity_id,
-        envelope.payload_version,
-        &payload_hash,
-    );
+    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 {
@@ -189,13 +184,16 @@ pub async fn verify_entity<E: Integrable>(
            expected_mac: envelope.mac,
            key_version: envelope.key_version,
        })
-        .await
-        ;
+        .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),
+        Ok(false) => Err(Error::MacMismatch {
+            entity_kind: E::KIND,
+        }),
+        Err(SendError::HandlerError(keyholder::Error::NotBootstrapped)) => {
+            Ok(AttestationStatus::Unavailable)
+        }
        Err(_) => Err(Error::KeyholderSend),
    }
 }
@@ -205,21 +203,32 @@ mod tests {
    use diesel::{ExpressionMethods as _, QueryDsl};
    use diesel_async::RunQueryDsl;
    use kameo::{actor::ActorRef, prelude::Spawn};
+    
+    use sha2::Digest;
+
+    

    use crate::{
        actors::keyholder::{Bootstrap, KeyHolder},
        db::{self, schema},
-        safe_cell::{SafeCell, SafeCellHandle as _},
    };
+    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

    use super::{Error, Integrable, sign_entity, verify_entity};
+    use super::hashing::Hashable;

-    #[derive(Clone, serde::Serialize)]
+    #[derive(Clone)]
    struct DummyEntity {
        payload_version: i32,
        payload: Vec<u8>,
    }

+    impl Hashable for DummyEntity {
+        fn hash<H: Digest>(&self, hasher: &mut H) {
+            self.payload_version.hash(hasher);
+            self.payload.hash(hasher);
+        }
+    }
    impl Integrable for DummyEntity {
        const KIND: &'static str = "dummy_entity";
    }
@@ -248,7 +257,9 @@ mod tests {
            payload: b"payload-v1".to_vec(),
        };

-        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID).await.unwrap();
+        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+            .await
+            .unwrap();

        let count: i64 = schema::integrity_envelope::table
            .filter(schema::integrity_envelope::entity_kind.eq("dummy_entity"))
@@ -259,7 +270,9 @@ mod tests {
            .unwrap();

        assert_eq!(count, 1, "envelope row must be created exactly once");
-        verify_entity(&mut conn, &keyholder, &entity, ENTITY_ID).await.unwrap();
+        verify_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+            .await
+            .unwrap();
    }

    #[tokio::test]
@@ -275,7 +288,9 @@ mod tests {
            payload: b"payload-v1".to_vec(),
        };

-        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID).await.unwrap();
+        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"))
@@ -304,7 +319,9 @@ mod tests {
            payload: b"payload-v1".to_vec(),
        };

-        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID).await.unwrap();
+        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+            .await
+            .unwrap();

        let tampered = DummyEntity {
            payload: b"payload-v1-but-tampered".to_vec(),
--- a/server/crates/arbiter-server/src/crypto/integrity/v1/hashing.rs
+++ b/server/crates/arbiter-server/src/crypto/integrity/v1/hashing.rs
@@ -0,0 +1,107 @@
+use hmac::digest::Digest;
+use std::collections::HashSet;
+
+/// Deterministically hash a value by feeding its fields into the hasher in a consistent order.
+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-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
@@ -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::*;

@@ -244,7 +210,6 @@ pub struct UseragentClient {
    pub public_key: Vec<u8>,
    pub created_at: SqliteTimestamp,
    pub updated_at: SqliteTimestamp,
-    pub key_type: KeyType,
 }

 #[derive(Models, Queryable, Debug, Insertable, Selectable)]
--- a/server/crates/arbiter-server/src/evm/mod.rs
+++ b/server/crates/arbiter-server/src/evm/mod.rs
@@ -21,8 +21,8 @@ use crate::{
        schema::{self, evm_transaction_log},
    },
    evm::policies::{
-        DatabaseID, EvalContext, EvalViolation, Grant, Policy, CombinedSettings, SharedGrantSettings,
-        SpecificGrant, SpecificMeaning, ether_transfer::EtherTransfer,
+        CombinedSettings, DatabaseID, EvalContext, EvalViolation, Grant, Policy,
+        SharedGrantSettings, SpecificGrant, SpecificMeaning, ether_transfer::EtherTransfer,
        token_transfers::TokenTransfer,
    },
 };
@@ -90,6 +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);
@@ -250,14 +258,9 @@ impl Engine {

                    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)?;
+                    integrity::sign_entity(conn, &keyholder, &full_grant, basic_grant.id)
+                        .await
+                        .map_err(|_| diesel::result::Error::RollbackTransaction)?;

                    QueryResult::Ok(basic_grant.id)
                })
@@ -342,3 +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
@@ -7,11 +7,12 @@ use diesel::{
 };
 use diesel_async::{AsyncConnection, RunQueryDsl};

-use serde::Serialize;
 use thiserror::Error;

 use crate::{
-    crypto::integrity::v1::Integrable, db::models::{self, EvmBasicGrant, EvmWalletAccess}, evm::utils
+    crypto::integrity::v1::Integrable,
+    db::models::{self, EvmBasicGrant, EvmWalletAccess},
+    evm::utils,
 };

 pub mod ether_transfer;
@@ -55,11 +56,14 @@ 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;

-#[derive(Debug, Serialize)]
+#[derive(Debug)]
 pub struct Grant<PolicySettings> {
    pub id: DatabaseID,
    pub common_settings_id: DatabaseID, // ID of the basic grant for shared-logic checks like rate limits and validity periods
@@ -123,19 +127,19 @@ pub enum SpecificMeaning {
    TokenTransfer(token_transfers::Meaning),
 }

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

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

-#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub struct SharedGrantSettings {
    pub wallet_access_id: i32,
    pub chain: ChainId,
@@ -196,7 +200,7 @@ pub enum SpecificGrant {
    TokenTransfer(token_transfers::Settings),
 }

-#[derive(Debug, Serialize)]
+#[derive(Debug)]
 pub struct CombinedSettings<PolicyGrant> {
    pub shared: SharedGrantSettings,
    pub specific: PolicyGrant,
@@ -216,3 +220,37 @@ impl<P: Integrable> Integrable for CombinedSettings<P> {
    const VERSION: i32 = P::VERSION;
 }

+use crate::crypto::integrity::hashing::Hashable;
+
+impl Hashable for TransactionRateLimit {
+    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
+        self.count.hash(hasher);
+        self.window.hash(hasher);
+    }
+}
+
+impl Hashable for VolumeRateLimit {
+    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
+        self.max_volume.hash(hasher);
+        self.window.hash(hasher);
+    }
+}
+
+impl Hashable for SharedGrantSettings {
+    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
+        self.wallet_access_id.hash(hasher);
+        self.chain.hash(hasher);
+        self.valid_from.hash(hasher);
+        self.valid_until.hash(hasher);
+        self.max_gas_fee_per_gas.hash(hasher);
+        self.max_priority_fee_per_gas.hash(hasher);
+        self.rate_limit.hash(hasher);
+    }
+}
+
+impl<P: Hashable> Hashable for CombinedSettings<P> {
+    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
+        self.shared.hash(hasher);
+        self.specific.hash(hasher);
+    }
+}
--- a/server/crates/arbiter-server/src/evm/policies/ether_transfer/mod.rs
+++ b/server/crates/arbiter-server/src/evm/policies/ether_transfer/mod.rs
@@ -52,7 +52,7 @@ impl From<Meaning> for SpecificMeaning {
 }

 // A grant for ether transfers, which can be scoped to specific target addresses and volume limits
-#[derive(Debug, Clone, serde::Serialize)]
+#[derive(Debug, Clone)]
 pub struct Settings {
    pub target: Vec<Address>,
    pub limit: VolumeRateLimit,
@@ -61,6 +61,15 @@ impl Integrable for Settings {
    const KIND: &'static str = "EtherTransfer";
 }

+use crate::crypto::integrity::hashing::Hashable;
+
+impl Hashable for Settings {
+    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
+        self.target.hash(hasher);
+        self.limit.hash(hasher);
+    }
+}
+
 impl From<Settings> for SpecificGrant {
    fn from(val: Settings) -> SpecificGrant {
        SpecificGrant::EtherTransfer(val)
--- a/server/crates/arbiter-server/src/evm/policies/ether_transfer/tests.rs
+++ b/server/crates/arbiter-server/src/evm/policies/ether_transfer/tests.rs
@@ -84,8 +84,6 @@ fn shared() -> SharedGrantSettings {
    }
 }

-// ── analyze ─────────────────────────────────────────────────────────────
-
 #[test]
 fn analyze_matches_empty_calldata() {
    let m = EtherTransfer::analyze(&ctx(ALLOWED, U256::from(1_000u64))).unwrap();
@@ -102,8 +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;
@@ -276,8 +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;
@@ -336,7 +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 crate::crypto::integrity::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() {
--- a/server/crates/arbiter-server/src/evm/policies/token_transfers/mod.rs
+++ b/server/crates/arbiter-server/src/evm/policies/token_transfers/mod.rs
@@ -1,17 +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 serde::Serialize;
-
 use crate::db::schema::{
    evm_basic_grant, evm_token_transfer_grant, evm_token_transfer_log,
    evm_token_transfer_volume_limit,
@@ -32,6 +20,16 @@ use crate::{
    },
    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};

@@ -64,7 +62,7 @@ impl From<Meaning> for SpecificMeaning {
 }

 // A grant for token transfers, which can be scoped to specific target addresses and volume limits
-#[derive(Debug, Clone, Serialize)]
+#[derive(Debug, Clone)]
 pub struct Settings {
    pub token_contract: Address,
    pub target: Option<Address>,
@@ -73,6 +71,17 @@ pub struct Settings {
 impl Integrable for Settings {
    const KIND: &'static str = "TokenTransfer";
 }
+
+use crate::crypto::integrity::hashing::Hashable;
+
+impl Hashable for Settings {
+    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
+        self.token_contract.hash(hasher);
+        self.target.hash(hasher);
+        self.volume_limits.hash(hasher);
+    }
+}
+
 impl From<Settings> for SpecificGrant {
    fn from(val: Settings) -> SpecificGrant {
        SpecificGrant::TokenTransfer(val)
--- a/server/crates/arbiter-server/src/evm/policies/token_transfers/tests.rs
+++ b/server/crates/arbiter-server/src/evm/policies/token_transfers/tests.rs
@@ -101,8 +101,6 @@ fn shared() -> SharedGrantSettings {
    }
 }

-// ── analyze ─────────────────────────────────────────────────────────────
-
 #[test]
 fn analyze_known_token_valid_calldata() {
    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
@@ -128,8 +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;
@@ -412,7 +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 crate::crypto::integrity::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() {
--- 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) }
@@ -108,7 +114,7 @@ impl Convert for VetError {
                        violations: violations.into_iter().map(Convert::convert).collect(),
                    })
                }
-                PolicyError::Database(_)| PolicyError::Integrity(_) => {
+                PolicyError::Database(_) | PolicyError::Integrity(_) => {
                    return EvmSignTransactionResult::Error(ProtoEvmError::Internal.into());
                }
            },
--- 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/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
@@ -1,21 +1,37 @@
+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, UserAgentCredentials, 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() {
@@ -37,10 +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
@@ -63,7 +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]
@@ -79,10 +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
@@ -115,8 +131,8 @@ pub async fn test_challenge_auth() {
        .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();
@@ -133,7 +149,7 @@ pub async fn test_challenge_auth() {
            &mut conn,
            &actors.key_holder,
            &UserAgentCredentials {
-                pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+                pubkey: new_key.verifying_key().into(),
                nonce: 1,
            },
            id,
@@ -151,7 +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
@@ -169,12 +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();
@@ -205,8 +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();
@@ -229,7 +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
@@ -254,8 +269,8 @@ pub async fn test_challenge_auth_rejects_invalid_signature() {
        .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();
@@ -272,7 +287,7 @@ pub async fn test_challenge_auth_rejects_invalid_signature() {
            &mut conn,
            &actors.key_holder,
            &UserAgentCredentials {
-                pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+                pubkey: new_key.verifying_key().into(),
                nonce: 1,
            },
            id,
@@ -290,7 +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
@@ -308,12 +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};

@@ -151,4 +150,4 @@ pub async fn test_unseal_retry_after_invalid_key() {
        let response = user_agent.ask(encrypted_key).await;
        assert!(matches!(response, Ok(())));
    }
-}
+}
Author	SHA1	Message	Date
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