housekeeping(server): clean too-broad visibility markers and organize imports

merge: refactor-integrity-check into main
docs: updated to new auth challenge format and removed stale TOCTOU race condition note
2026-04-18 13:30:09 +02:00 · 2026-04-18 13:19:13 +02:00 · 2026-04-17 18:25:55 +02:00 · 2026-04-17 18:19:51 +02:00 · 2026-04-17 17:58:22 +02:00 · 2026-04-17 17:44:42 +02:00
99 changed files with 2022 additions and 1591 deletions
--- a/IMPLEMENTATION.md
+++ b/IMPLEMENTATION.md
@@ -29,38 +29,23 @@ flowchart TD
    A([Client connects]) --> B[Receive AuthChallengeRequest]
    B --> C{pubkey in DB?}

-    C -- yes --> D[Read nonce\nIncrement nonce in DB]
-    D --> G
+    C -- yes --> G[Generate AuthChallenge]

    C -- no --> E[Ask all UserAgents:\nClientConnectionRequest]
    E --> F{First response}
    F -- denied --> Z([Reject connection])
    F -- approved --> F2[Cancel remaining\nUserAgent requests]
-    F2 --> F3[INSERT client\nnonce = 1]
-    F3 --> G[Send AuthChallenge\nwith nonce]
+    F2 --> F3[INSERT client]
+    F3 --> G

-    G --> H[Receive AuthChallengeSolution]
-    H --> I{Signature valid?}
-    I -- no --> Z
-    I -- yes --> J([Session started])
+    G --> H[Send AuthChallenge\ntimestamp + random bytes]
+    H --> I[Receive AuthChallengeSolution]
+    I --> K{Signature valid?}
+    K -- no --> Z
+    K -- yes --> J([Session started])
 ```

-### Known Issue: Concurrent Registration Race (TOCTOU)
-
-Two connections presenting the same previously-unknown public key can race through the approval flow simultaneously:
-
-1. Both check the DB → neither is registered.
-2. Both request approval from user agents → both receive approval.
-3. Both `INSERT` the client record → the second insert silently overwrites the first, resetting the nonce.
-
-This means the first connection's nonce is invalidated by the second, causing its challenge verification to fail. A fix requires either serialising new-client registration (e.g. an in-memory lock keyed on pubkey) or replacing the separate check + insert with an `INSERT OR IGNORE` / upsert guarded by a unique constraint on `public_key`.
-
-### Nonce Semantics
-
-The `program_client.nonce` column stores the **next usable nonce** — i.e. it is always one ahead of the nonce last issued in a challenge.
-
- **New client:** inserted with `nonce = 1`; the first challenge is issued with `nonce = 0`.
- **Existing client:** the current DB value is read and used as the challenge nonce, then immediately incremented within the same exclusive transaction, preventing replay.
+Auth challenges are generated from fresh random bytes plus a timestamp. They are signed as the canonical challenge payload and are not persisted in `program_client`.

 ---

--- a/protobufs/client/auth.proto
+++ b/protobufs/client/auth.proto
@@ -10,8 +10,8 @@ message AuthChallengeRequest {
 }

 message AuthChallenge {
-  bytes pubkey = 1;
-  int32 nonce = 2;
+  uint64 timestamp_nanos = 1;
+  bytes random = 2;
 }

 message AuthChallengeSolution {
--- a/protobufs/user_agent/auth.proto
+++ b/protobufs/user_agent/auth.proto
@@ -8,7 +8,8 @@ message AuthChallengeRequest {
 }

 message AuthChallenge {
-  int32 nonce = 1;
+  uint64 timestamp_nanos = 1;
+  bytes random = 2;
 }

 message AuthChallengeSolution {
--- a/server/Cargo.lock
+++ b/server/Cargo.lock
@@ -95,7 +95,7 @@ dependencies = [
 "either",
 "k256",
 "once_cell",
- "rand 0.8.5",
+ "rand 0.8.6",
 "secp256k1",
 "serde",
 "serde_json",
@@ -516,7 +516,7 @@ dependencies = [
 "alloy-signer",
 "async-trait",
 "k256",
- "rand 0.8.5",
+ "rand 0.8.6",
 "thiserror 2.0.18",
 ]

@@ -683,6 +683,7 @@ dependencies = [
 "arbiter-crypto",
 "arbiter-proto",
 "async-trait",
+ "chrono",
 "http",
 "rand 0.10.1",
 "rustls-webpki",
@@ -696,13 +697,25 @@ dependencies = [
 name = "arbiter-crypto"
 version = "0.1.0"
 dependencies = [
- "base64",
+ "alloy",
+ "chrono",
+ "hmac",
 "memsafe",
 "ml-dsa",
 "rand 0.10.1",
 "x-wing",
 ]

+[[package]]
+name = "arbiter-macros"
+version = "0.1.0"
+dependencies = [
+ "arbiter-crypto",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.117",
+]
+
 [[package]]
 name = "arbiter-proto"
 version = "0.1.0"
@@ -737,6 +750,7 @@ dependencies = [
 "alloy",
 "anyhow",
 "arbiter-crypto",
+ "arbiter-macros",
 "arbiter-proto",
 "arbiter-tokens-registry",
 "argon2",
@@ -970,7 +984,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1df2c09229cbc5a028b1d70e00fdb2acee28b1055dfb5ca73eea49c5a25c4e7c"
 dependencies = [
 "num-traits",
- "rand 0.8.5",
+ "rand 0.8.6",
 ]

 [[package]]
@@ -980,7 +994,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94893f1e0c6eeab764ade8dc4c0db24caf4fe7cbbaafc0eba0a9030f447b5185"
 dependencies = [
 "num-traits",
- "rand 0.8.5",
+ "rand 0.8.6",
 ]

 [[package]]
@@ -990,7 +1004,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "246a225cc6131e9ee4f24619af0f19d67761fff15d7ccc22e42b80846e69449a"
 dependencies = [
 "num-traits",
- "rand 0.8.5",
+ "rand 0.8.6",
 ]

 [[package]]
@@ -1096,9 +1110,9 @@ checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"

 [[package]]
 name = "aws-lc-rs"
-version = "1.16.2"
+version = "1.16.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a054912289d18629dc78375ba2c3726a3afe3ff71b4edba9dedfca0e3446d1fc"
+checksum = "0ec6fb3fe69024a75fa7e1bfb48aa6cf59706a101658ea01bfd33b2b248a038f"
 dependencies = [
 "aws-lc-sys",
 "untrusted 0.7.1",
@@ -1107,9 +1121,9 @@ dependencies = [

 [[package]]
 name = "aws-lc-sys"
-version = "0.39.1"
+version = "0.40.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "83a25cf98105baa966497416dbd42565ce3a8cf8dbfd59803ec9ad46f3126399"
+checksum = "f50037ee5e1e41e7b8f9d161680a725bd1626cb6f8c7e901f91f942850852fe7"
 dependencies = [
 "cc",
 "cmake",
@@ -1247,9 +1261,9 @@ dependencies = [

 [[package]]
 name = "bitflags"
-version = "2.11.0"
+version = "2.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "843867be96c8daad0d758b57df9392b6d8d271134fce549de6ce169ff98a92af"
+checksum = "c4512299f36f043ab09a583e57bceb5a5aab7a73db1805848e8fef3c9e8c78b3"

 [[package]]
 name = "bitvec"
@@ -1520,11 +1534,12 @@ checksum = "a6ef517f0926dd24a1582492c791b6a4818a4d94e789a334894aa15b0d12f55c"

 [[package]]
 name = "const_format"
-version = "0.2.35"
+version = "0.2.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7faa7469a93a566e9ccc1c73fe783b4a65c274c5ace346038dca9c39fe0030ad"
+checksum = "4481a617ad9a412be3b97c5d403fef8ed023103368908b9c50af598ff467cc1e"
 dependencies = [
 "const_format_proc_macros",
+ "konst",
 ]

 [[package]]
@@ -2241,7 +2256,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "835c052cb0c08c1acf6ffd71c022172e18723949c8282f2b9f27efbc51e64534"
 dependencies = [
 "byteorder",
- "rand 0.8.5",
+ "rand 0.8.6",
 "rustc-hex",
 "static_assertions",
 ]
@@ -2660,9 +2675,9 @@ dependencies = [

 [[package]]
 name = "hyper-rustls"
-version = "0.27.8"
+version = "0.27.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c2b52f86d1d4bc0d6b4e6826d960b1b333217e07d36b882dca570a5e1c48895b"
+checksum = "33ca68d021ef39cf6463ab54c1d0f5daf03377b70561305bb89a8f83aab66e0f"
 dependencies = [
 "http",
 "hyper",
@@ -3125,6 +3140,21 @@ dependencies = [
 "rand_core 0.10.1",
 ]

+[[package]]
+name = "konst"
+version = "0.2.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "128133ed7824fcd73d6e7b17957c5eb7bacb885649bd8c69708b2331a10bcefb"
+dependencies = [
+ "konst_macro_rules",
+]
+
+[[package]]
+name = "konst_macro_rules"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4933f3f57a8e9d9da04db23fb153356ecaf00cbd14aee46279c33dc80925c37"
+
 [[package]]
 name = "lazy_static"
 version = "1.5.0"
@@ -4061,9 +4091,9 @@ checksum = "dc33ff2d4973d518d823d61aa239014831e521c75da58e3df4840d3f47749d09"

 [[package]]
 name = "rand"
-version = "0.8.5"
+version = "0.8.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+checksum = "5ca0ecfa931c29007047d1bc58e623ab12e5590e8c7cc53200d5202b69266d8a"
 dependencies = [
 "libc",
 "rand_chacha 0.3.1",
@@ -4376,7 +4406,7 @@ dependencies = [
 "parity-scale-codec",
 "primitive-types",
 "proptest",
- "rand 0.8.5",
+ "rand 0.8.6",
 "rand 0.9.4",
 "rlp",
 "ruint-macro",
@@ -4515,9 +4545,9 @@ checksum = "f87165f0995f63a9fbeea62b64d10b4d9d8e78ec6d7d51fb2125fda7bb36788f"

 [[package]]
 name = "rustls-webpki"
-version = "0.103.11"
+version = "0.103.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "20a6af516fea4b20eccceaf166e8aa666ac996208e8a644ce3ef5aa783bc7cd4"
+checksum = "8279bb85272c9f10811ae6a6c547ff594d6a7f3c6c6b02ee9726d1d0dcfcdd06"
 dependencies = [
 "aws-lc-rs",
 "ring",
@@ -4622,7 +4652,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b50c5943d326858130af85e049f2661ba3c78b26589b8ab98e65e80ae44a1252"
 dependencies = [
 "bitcoin_hashes",
- "rand 0.8.5",
+ "rand 0.8.6",
 "secp256k1-sys",
 "serde",
 ]
@@ -5295,9 +5325,9 @@ checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"

 [[package]]
 name = "tokio"
-version = "1.51.1"
+version = "1.52.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f66bf9585cda4b724d3e78ab34b73fb2bbaba9011b9bfdf69dc836382ea13b8c"
+checksum = "b67dee974fe86fd92cc45b7a95fdd2f99a36a6d7b0d431a231178d3d670bbcc6"
 dependencies = [
 "bytes",
 "libc",
@@ -5711,9 +5741,9 @@ checksum = "b6c140620e7ffbb22c2dee59cafe6084a59b5ffc27a8859a5f0d494b5d52b6be"

 [[package]]
 name = "uuid"
-version = "1.23.0"
+version = "1.23.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5ac8b6f42ead25368cf5b098aeb3dc8a1a2c05a3eee8a9a1a68c640edbfc79d9"
+checksum = "ddd74a9687298c6858e9b88ec8935ec45d22e8fd5e6394fa1bd4e99a87789c76"
 dependencies = [
 "js-sys",
 "wasm-bindgen",
@@ -5773,11 +5803,11 @@ checksum = "ccf3ec651a847eb01de73ccad15eb7d99f80485de043efb2f370cd654f4ea44b"

 [[package]]
 name = "wasip2"
-version = "1.0.2+wasi-0.2.9"
+version = "1.0.3+wasi-0.2.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9517f9239f02c069db75e65f174b3da828fe5f5b945c4dd26bd25d89c03ebcf5"
+checksum = "20064672db26d7cdc89c7798c48a0fdfac8213434a1186e5ef29fd560ae223d6"
 dependencies = [
- "wit-bindgen",
+ "wit-bindgen 0.57.1",
 ]

 [[package]]
@@ -5786,7 +5816,7 @@ version = "0.4.0+wasi-0.3.0-rc-2026-01-06"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5428f8bf88ea5ddc08faddef2ac4a67e390b88186c703ce6dbd955e1c145aca5"
 dependencies = [
- "wit-bindgen",
+ "wit-bindgen 0.51.0",
 ]

 [[package]]
@@ -5914,9 +5944,9 @@ dependencies = [

 [[package]]
 name = "webpki-root-certs"
-version = "1.0.6"
+version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "804f18a4ac2676ffb4e8b5b5fa9ae38af06df08162314f96a68d2a363e21a8ca"
+checksum = "f31141ce3fc3e300ae89b78c0dd67f9708061d1d2eda54b8209346fd6be9a92c"
 dependencies = [
 "rustls-pki-types",
 ]
@@ -6260,6 +6290,12 @@ dependencies = [
 "wit-bindgen-rust-macro",
 ]

+[[package]]
+name = "wit-bindgen"
+version = "0.57.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ebf944e87a7c253233ad6766e082e3cd714b5d03812acc24c318f549614536e"
+
 [[package]]
 name = "wit-bindgen-core"
 version = "0.51.0"
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -48,4 +48,4 @@ ml-dsa = { version = "0.1.0-rc.8", features = ["zeroize"] }
 base64 = "0.22.1"
 kameo = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
 kameo_actors = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
-
+hmac = "0.12.1"
--- a/server/crates/arbiter-client/Cargo.toml
+++ b/server/crates/arbiter-client/Cargo.toml
@@ -24,3 +24,4 @@ http = "1.4.0"
 rustls-webpki = { version = "0.103.10", features = ["aws-lc-rs"] }
 async-trait.workspace = true
 rand.workspace = true
+chrono.workspace = true
--- a/server/crates/arbiter-client/src/auth.rs
+++ b/server/crates/arbiter-client/src/auth.rs
@@ -1,4 +1,8 @@
-use arbiter_crypto::authn::{CLIENT_CONTEXT, SigningKey, format_challenge};
+use crate::{
+    storage::StorageError,
+    transport::{ClientTransport, next_request_id},
+};
+use arbiter_crypto::authn::{self, CLIENT_CONTEXT, SigningKey};
 use arbiter_proto::{
    ClientMetadata,
    proto::{
@@ -16,13 +20,12 @@ use arbiter_proto::{
    },
 };

-use crate::{
-    storage::StorageError,
-    transport::{ClientTransport, next_request_id},
-};
+use chrono::DateTime;

 #[derive(Debug, thiserror::Error)]
 pub enum AuthError {
+    #[error("Server sent invalid auth challenge")]
+    InvalidChallenge,
    #[error("Auth challenge was not returned by server")]
    MissingAuthChallenge,

@@ -98,7 +101,15 @@ async fn send_auth_challenge_solution(
    key: &SigningKey,
    challenge: AuthChallenge,
 ) -> std::result::Result<(), AuthError> {
-    let challenge_payload = format_challenge(challenge.nonce, &challenge.pubkey);
+    let timestamp = DateTime::from_timestamp_nanos(challenge.timestamp_nanos as i64);
+    let challenge = authn::AuthChallenge {
+        nonce: *challenge
+            .random
+            .as_array()
+            .ok_or(AuthError::InvalidChallenge)?,
+        timestamp,
+    };
+    let challenge_payload: Vec<u8> = challenge.format();
    let signature = key
        .sign_message(&challenge_payload, CLIENT_CONTEXT)
        .map_err(|_| AuthError::UnexpectedAuthResponse)?
--- a/server/crates/arbiter-client/src/bin/test_connect.rs
+++ b/server/crates/arbiter-client/src/bin/test_connect.rs
@@ -1,8 +1,8 @@
-use std::io::{self, Write};
-
 use arbiter_client::ArbiterClient;
 use arbiter_proto::{ClientMetadata, url::ArbiterUrl};

+use std::io::{self, Write};
+
 #[tokio::main]
 async fn main() {
    println!("Testing connection to Arbiter server...");
--- a/server/crates/arbiter-client/src/client.rs
+++ b/server/crates/arbiter-client/src/client.rs
@@ -1,21 +1,20 @@
-use arbiter_crypto::authn::SigningKey;
-use arbiter_proto::{
-    ClientMetadata, proto::arbiter_service_client::ArbiterServiceClient, url::ArbiterUrl,
-};
-use std::sync::Arc;
-use tokio::sync::{Mutex, mpsc};
-use tokio_stream::wrappers::ReceiverStream;
-use tonic::transport::ClientTlsConfig;
-
+#[cfg(feature = "evm")]
+use crate::wallets::evm::ArbiterEvmWallet;
 use crate::{
    StorageError,
    auth::{AuthError, authenticate},
    storage::{FileSigningKeyStorage, SigningKeyStorage},
    transport::{BUFFER_LENGTH, ClientTransport},
 };
+use arbiter_crypto::authn::SigningKey;
+use arbiter_proto::{
+    ClientMetadata, proto::arbiter_service_client::ArbiterServiceClient, url::ArbiterUrl,
+};

-#[cfg(feature = "evm")]
-use crate::wallets::evm::ArbiterEvmWallet;
+use std::sync::Arc;
+use tokio::sync::{Mutex, mpsc};
+use tokio_stream::wrappers::ReceiverStream;
+use tonic::transport::ClientTlsConfig;

 #[derive(Debug, thiserror::Error)]
 pub enum Error {
--- a/server/crates/arbiter-client/src/storage.rs
+++ b/server/crates/arbiter-client/src/storage.rs
@@ -1,5 +1,6 @@
 use arbiter_crypto::authn::SigningKey;
 use arbiter_proto::home_path;
+
 use std::path::{Path, PathBuf};

 #[derive(Debug, thiserror::Error)]
--- a/server/crates/arbiter-client/src/transport.rs
+++ b/server/crates/arbiter-client/src/transport.rs
@@ -1,4 +1,5 @@
 use arbiter_proto::proto::client::{ClientRequest, ClientResponse};
+
 use std::sync::atomic::{AtomicI32, Ordering};
 use tokio::sync::mpsc;

--- a/server/crates/arbiter-client/src/wallets/evm.rs
+++ b/server/crates/arbiter-client/src/wallets/evm.rs
@@ -1,13 +1,4 @@
-use alloy::{
-    consensus::SignableTransaction,
-    network::TxSigner,
-    primitives::{Address, B256, ChainId, Signature},
-    signers::{Error, Result, Signer},
-};
-use async_trait::async_trait;
-use std::sync::Arc;
-use tokio::sync::Mutex;
-
+use crate::transport::{ClientTransport, next_request_id};
 use arbiter_proto::proto::{
    client::{
        ClientRequest,
@@ -25,7 +16,15 @@ use arbiter_proto::proto::{
    shared::evm::TransactionEvalError,
 };

-use crate::transport::{ClientTransport, next_request_id};
+use alloy::{
+    consensus::SignableTransaction,
+    network::TxSigner,
+    primitives::{Address, B256, ChainId, Signature},
+    signers::{Error, Result, Signer},
+};
+use async_trait::async_trait;
+use std::sync::Arc;
+use tokio::sync::Mutex;

 /// A typed error payload returned by [`ArbiterEvmWallet`] transaction signing.
 ///
--- a/server/crates/arbiter-crypto/Cargo.toml
+++ b/server/crates/arbiter-crypto/Cargo.toml
@@ -6,14 +6,16 @@ edition = "2024"
 [dependencies]
 ml-dsa = {workspace = true, optional = true }
 rand = {workspace = true, optional = true}
-base64 = {workspace = true, optional = true }
 memsafe = {version = "0.4.0", optional = true}
+hmac.workspace = true
+alloy.workspace = true
 x-wing = { version = "0.1.0-rc.0", features = ["zeroize"] }
+chrono.workspace = true

 [lints]
 workspace = true

 [features]
 default = ["authn", "safecell"]
-authn = ["dep:ml-dsa", "dep:rand", "dep:base64"]
+authn = ["dep:ml-dsa", "dep:rand"]
 safecell = ["dep:memsafe"]
--- a/server/crates/arbiter-crypto/src/authn/v1.rs
+++ b/server/crates/arbiter-crypto/src/authn/v1.rs
@@ -1,17 +1,55 @@
-use std::hash::Hash;
-
-use base64::{Engine as _, prelude::BASE64_STANDARD};
+use chrono::{DateTime, Utc};
+use hmac::digest::Digest;
 use ml_dsa::{
    EncodedVerifyingKey, Error, KeyGen, MlDsa87, Seed, Signature as MlDsaSignature,
    SigningKey as MlDsaSigningKey, VerifyingKey as MlDsaVerifyingKey, signature::Keypair as _,
 };
+use rand::RngExt;

 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()
+const NONCE_SIZE: usize = 32;
+
+#[derive(Debug, Clone)]
+pub struct AuthChallenge {
+    pub nonce: [u8; NONCE_SIZE],
+    pub timestamp: DateTime<Utc>,
+}
+
+impl AuthChallenge {
+    pub fn generate(rng: &mut impl rand::CryptoRng) -> Self {
+        let timestamp = Utc::now();
+        let nonce = {
+            let mut array = [0; NONCE_SIZE];
+            rng.fill(&mut array);
+            array
+        };
+
+        Self { nonce, timestamp }
+    }
+
+    pub fn format(&self) -> Vec<u8> {
+        {
+            let mut buffer = Vec::from(self.nonce);
+
+            let stamp = self
+                .timestamp
+                .timestamp_nanos_opt()
+                .expect("We would be long dead by the time this triggers :)");
+            buffer.extend_from_slice(stamp.to_be_bytes().as_slice());
+
+            buffer
+        }
+    }
+
+    pub fn from_parts(nonce: &[u8], timestamp: i64) -> Result<Self, ()> {
+        let random_nonce = nonce.as_array().ok_or(())?;
+        Ok(AuthChallenge {
+            nonce: *random_nonce,
+            timestamp: DateTime::from_timestamp_nanos(timestamp),
+        })
+    }
 }

 pub type KeyParams = MlDsa87;
@@ -19,9 +57,9 @@ pub type KeyParams = MlDsa87;
 #[derive(Clone, Debug, PartialEq)]
 pub struct PublicKey(Box<MlDsaVerifyingKey<KeyParams>>);

-impl Hash for PublicKey {
-    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
-        self.to_bytes().hash(state);
+impl crate::hashing::Hashable for PublicKey {
+    fn hash<H: Digest>(&self, hasher: &mut H) {
+        hasher.update(self.to_bytes());
    }
 }

@@ -33,21 +71,19 @@ pub struct SigningKey(Box<MlDsaSigningKey<KeyParams>>);

 impl PublicKey {
    pub fn to_bytes(&self) -> Vec<u8> {
-        self.0.encode().to_vec()
+        self.0.encode().0.to_vec()
    }

-    pub fn verify(&self, nonce: i32, context: &[u8], signature: &Signature) -> bool {
-        self.0.verify_with_context(
-            &format_challenge(nonce, &self.to_bytes()),
-            context,
-            &signature.0,
-        )
+    pub fn verify(&self, challenge: &AuthChallenge, context: &[u8], signature: &Signature) -> bool {
+        let challenge = challenge.format();
+        self.0
+            .verify_with_context(&challenge, context, &signature.0)
    }
 }

 impl Signature {
    pub fn to_bytes(&self) -> Vec<u8> {
-        self.0.encode().to_vec()
+        self.0.encode().0.to_vec()
    }
 }

@@ -75,11 +111,14 @@ impl SigningKey {
            .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,
-        )
+    pub fn sign_challenge(
+        &self,
+        challenge: &AuthChallenge,
+        context: &[u8],
+    ) -> Result<Signature, Error> {
+        let challenge = challenge.format();
+
+        self.sign_message(&challenge, context)
    }
 }

@@ -140,6 +179,8 @@ impl TryFrom<&'_ [u8]> for Signature {
 mod tests {
    use ml_dsa::{KeyGen, MlDsa87, signature::Keypair as _};

+    use crate::authn::AuthChallenge;
+
    use super::{CLIENT_CONTEXT, PublicKey, Signature, SigningKey, USERAGENT_CONTEXT};

    #[test]
@@ -169,13 +210,13 @@ mod tests {
    fn challenge_verification_uses_context_and_canonical_key_bytes() {
        let key = SigningKey::generate();
        let public_key = key.public_key();
-        let nonce = 17;
+        let challenge = AuthChallenge::generate(&mut rand::rng());
        let signature = key
-            .sign_challenge(nonce, CLIENT_CONTEXT)
+            .sign_challenge(&challenge, CLIENT_CONTEXT)
            .expect("signature should be created");

-        assert!(public_key.verify(nonce, CLIENT_CONTEXT, &signature));
-        assert!(!public_key.verify(nonce, USERAGENT_CONTEXT, &signature));
+        assert!(public_key.verify(&challenge, CLIENT_CONTEXT, &signature));
+        assert!(!public_key.verify(&challenge, USERAGENT_CONTEXT, &signature));
    }

    #[test]
@@ -185,10 +226,16 @@ mod tests {

        assert_eq!(restored.public_key(), original.public_key());

+        let challenge = AuthChallenge::generate(&mut rand::rng());
+
        let signature = restored
-            .sign_challenge(9, CLIENT_CONTEXT)
+            .sign_challenge(&challenge, CLIENT_CONTEXT)
            .expect("signature should be created");

-        assert!(restored.public_key().verify(9, CLIENT_CONTEXT, &signature));
+        assert!(
+            restored
+                .public_key()
+                .verify(&challenge, CLIENT_CONTEXT, &signature)
+        );
    }
 }
--- a/server/crates/arbiter-server/src/crypto/integrity/v1/hashing.rs
+++ b/server/crates/arbiter-server/src/crypto/integrity/v1/hashing.rs
@@ -1,21 +1,26 @@
-use hmac::digest::Digest;
 use std::collections::HashSet;

+pub use hmac::digest::Digest;
+
 /// Deterministically hash a value by feeding its fields into the hasher in a consistent order.
+#[diagnostic::on_unimplemented(
+    note = "for local types consider adding `#[derive(arbiter_macros::Hashable)]` to your `{Self}` type",
+    note = "for types from other crates check whether the crate offers a `Hashable` implementation"
+)]
 pub trait Hashable {
    fn hash<H: Digest>(&self, hasher: &mut H);
 }

 macro_rules! impl_numeric {
-($($t:ty),*) => {
-    $(
-        impl Hashable for $t {
-            fn hash<H: Digest>(&self, hasher: &mut H) {
-                hasher.update(&self.to_be_bytes());
+    ($($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);
--- a/server/crates/arbiter-crypto/src/lib.rs
+++ b/server/crates/arbiter-crypto/src/lib.rs
@@ -1,6 +1,6 @@
 #[cfg(feature = "authn")]
 pub mod authn;
-
+pub mod hashing;
 #[cfg(feature = "safecell")]
 pub mod safecell;

--- a/server/crates/arbiter-crypto/src/safecell.rs
+++ b/server/crates/arbiter-crypto/src/safecell.rs
@@ -1,7 +1,9 @@
-use std::ops::{Deref, DerefMut};
-use std::{any::type_name, fmt};
-
 use memsafe::MemSafe;
+use std::{
+    any::type_name,
+    fmt,
+    ops::{Deref, DerefMut},
+};

 pub trait SafeCellHandle<T> {
    type CellRead<'a>: Deref<Target = T>
--- a/server/crates/arbiter-macros/Cargo.toml
+++ b/server/crates/arbiter-macros/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "arbiter-macros"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "2.0", features = ["derive", "fold", "full", "visit-mut"] }
+
+[dev-dependencies]
+arbiter-crypto = { path = "../arbiter-crypto" }
+
+[lints]
+workspace = true
--- a/server/crates/arbiter-macros/src/hashable.rs
+++ b/server/crates/arbiter-macros/src/hashable.rs
@@ -0,0 +1,131 @@
+use crate::utils::{HASHABLE_TRAIT_PATH, HMAC_DIGEST_PATH};
+
+use proc_macro2::{Span, TokenStream, TokenTree};
+use quote::quote;
+use syn::{DataStruct, DeriveInput, Fields, Generics, Index, parse_quote, spanned::Spanned};
+
+pub(crate) fn derive(input: &DeriveInput) -> TokenStream {
+    match &input.data {
+        syn::Data::Struct(struct_data) => hashable_struct(input, struct_data),
+        syn::Data::Enum(_) => {
+            syn::Error::new_spanned(input, "Hashable can currently be derived only for structs")
+                .to_compile_error()
+        }
+        syn::Data::Union(_) => {
+            syn::Error::new_spanned(input, "Hashable cannot be derived for unions")
+                .to_compile_error()
+        }
+    }
+}
+
+fn hashable_struct(input: &DeriveInput, struct_data: &syn::DataStruct) -> TokenStream {
+    let ident = &input.ident;
+    let hashable_trait = HASHABLE_TRAIT_PATH.to_path();
+    let hmac_digest = HMAC_DIGEST_PATH.to_path();
+    let generics = add_hashable_bounds(input.generics.clone(), &hashable_trait);
+    let field_accesses = collect_field_accesses(struct_data);
+    let hash_calls = build_hash_calls(&field_accesses, &hashable_trait);
+
+    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
+
+    quote! {
+        #[automatically_derived]
+        impl #impl_generics #hashable_trait for #ident #ty_generics #where_clause {
+            fn hash<H: #hmac_digest>(&self, hasher: &mut H) {
+                #(#hash_calls)*
+            }
+        }
+    }
+}
+
+fn add_hashable_bounds(mut generics: Generics, hashable_trait: &syn::Path) -> Generics {
+    for type_param in generics.type_params_mut() {
+        type_param.bounds.push(parse_quote!(#hashable_trait));
+    }
+
+    generics
+}
+
+struct FieldAccess {
+    access: TokenStream,
+    span: Span,
+}
+
+fn collect_field_accesses(struct_data: &DataStruct) -> Vec<FieldAccess> {
+    match &struct_data.fields {
+        Fields::Named(fields) => {
+            // Keep deterministic alphabetical order for named fields.
+            // Do not remove this sort, because it keeps hash output stable regardless of source order.
+            let mut named_fields = fields
+                .named
+                .iter()
+                .map(|field| {
+                    let name = field
+                        .ident
+                        .as_ref()
+                        .expect("Fields::Named(fields) must have names")
+                        .clone();
+                    (name.to_string(), name)
+                })
+                .collect::<Vec<_>>();
+
+            named_fields.sort_by(|a, b| a.0.cmp(&b.0));
+
+            named_fields
+                .into_iter()
+                .map(|(_, name)| FieldAccess {
+                    access: quote! { #name },
+                    span: name.span(),
+                })
+                .collect()
+        }
+        Fields::Unnamed(fields) => fields
+            .unnamed
+            .iter()
+            .enumerate()
+            .map(|(i, field)| FieldAccess {
+                access: {
+                    let index = Index::from(i);
+                    quote! { #index }
+                },
+                span: field.ty.span(),
+            })
+            .collect(),
+        Fields::Unit => Vec::new(),
+    }
+}
+
+fn build_hash_calls(
+    field_accesses: &[FieldAccess],
+    hashable_trait: &syn::Path,
+) -> Vec<TokenStream> {
+    field_accesses
+        .iter()
+        .map(|field| {
+            let access = &field.access;
+            let call = quote! {
+                #hashable_trait::hash(&self.#access, hasher);
+            };
+
+            respan(call, field.span)
+        })
+        .collect()
+}
+
+/// Recursively set span on all tokens, including interpolated ones.
+fn respan(tokens: TokenStream, span: Span) -> TokenStream {
+    tokens
+        .into_iter()
+        .map(|tt| match tt {
+            TokenTree::Group(g) => {
+                let mut new = proc_macro2::Group::new(g.delimiter(), respan(g.stream(), span));
+                new.set_span(span);
+                TokenTree::Group(new)
+            }
+            mut other => {
+                other.set_span(span);
+                other
+            }
+        })
+        .collect()
+}
--- a/server/crates/arbiter-macros/src/lib.rs
+++ b/server/crates/arbiter-macros/src/lib.rs
@@ -0,0 +1,10 @@
+use syn::{DeriveInput, parse_macro_input};
+
+mod hashable;
+mod utils;
+
+#[proc_macro_derive(Hashable)]
+pub fn derive_hashable(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+    hashable::derive(&input).into()
+}
--- a/server/crates/arbiter-macros/src/utils.rs
+++ b/server/crates/arbiter-macros/src/utils.rs
@@ -0,0 +1,19 @@
+pub(crate) struct ToPath(pub(crate) &'static str);
+
+impl ToPath {
+    pub(crate) fn to_path(&self) -> syn::Path {
+        syn::parse_str(self.0).expect("Invalid path")
+    }
+}
+
+macro_rules! ensure_path {
+    ($path:path) => {{
+        #[cfg(test)]
+        #[expect(unused_imports)]
+        use $path as _;
+        ToPath(stringify!($path))
+    }};
+}
+
+pub(crate) const HASHABLE_TRAIT_PATH: ToPath = ensure_path!(::arbiter_crypto::hashing::Hashable);
+pub(crate) const HMAC_DIGEST_PATH: ToPath = ensure_path!(::arbiter_crypto::hashing::Digest);
--- a/server/crates/arbiter-proto/src/transport.rs
+++ b/server/crates/arbiter-proto/src/transport.rs
@@ -54,10 +54,9 @@
 //!   as a closed outbound channel.
 //! - [`Bi::recv`] returns `None` when the underlying transport closes.
 //! - Message translation is intentionally out of scope for this module.
-
-use std::marker::PhantomData;
-
 use async_trait::async_trait;
+use kameo::{error::Infallible, prelude::*};
+use std::marker::PhantomData;

 /// Errors returned by transport adapters implementing [`Bi`].
 #[derive(thiserror::Error, Debug)]
@@ -191,3 +190,29 @@ where
 }

 pub mod grpc;
+
+#[derive(thiserror::Error, Debug)]
+pub enum ForwardError<I> {
+    #[error("Transport error: {0}")]
+    Transport(#[from] Error),
+    #[error("Actor delivery error: {0}")]
+    Actor(SendError<I>),
+}
+
+pub async fn forward_to_actor<Transport, Inbound, Outbound, Handler>(
+    transport: &mut Transport,
+    actor: &ActorRef<Handler>,
+) -> Result<(), ForwardError<Inbound>>
+where
+    Transport: Bi<Inbound, <Outbound as Reply>::Ok>,
+    Handler: Actor + Message<Inbound, Reply = Outbound>,
+    Inbound: Send + 'static,
+    Outbound: Send + 'static + Reply<Error = Infallible>, // `Infallible` to enforce contract that `Outbound` carries handler-level error
+{
+    while let Some(request) = transport.recv().await {
+        let resp = actor.ask(request).await.map_err(ForwardError::Actor)?;
+        transport.send(resp).await?
+    }
+
+    Err(Error::ChannelClosed.into())
+}
--- a/server/crates/arbiter-proto/src/transport/grpc.rs
+++ b/server/crates/arbiter-proto/src/transport/grpc.rs
@@ -1,10 +1,10 @@
+use super::{Bi, Receiver, Sender};
+
 use async_trait::async_trait;
 use futures::StreamExt;
 use tokio::sync::mpsc;
 use tokio_stream::wrappers::ReceiverStream;

-use super::{Bi, Receiver, Sender};
-
 pub struct GrpcSender<Outbound> {
    tx: mpsc::Sender<Result<Outbound, tonic::Status>>,
 }
--- a/server/crates/arbiter-proto/src/url.rs
+++ b/server/crates/arbiter-proto/src/url.rs
@@ -1,7 +1,6 @@
-use std::fmt::Display;
-
 use base64::{Engine as _, prelude::BASE64_URL_SAFE};
 use rustls_pki_types::CertificateDer;
+use std::fmt::Display;

 const ARBITER_URL_SCHEME: &str = "arbiter";
 const CERT_QUERY_KEY: &str = "cert";
--- a/server/crates/arbiter-server/Cargo.toml
+++ b/server/crates/arbiter-server/Cargo.toml
@@ -18,6 +18,7 @@ diesel-async = { version = "0.8.0", features = [
 ] }
 arbiter-proto.path = "../arbiter-proto"
 arbiter-crypto.path = "../arbiter-crypto"
+arbiter-macros.path = "../arbiter-macros"
 tracing.workspace = true
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 tonic.workspace = true
@@ -44,7 +45,7 @@ restructed = "0.2.2"
 strum = { version = "0.28.0", features = ["derive"] }
 pem = "3.0.6"
 sha2.workspace = true
-hmac = "0.12"
+hmac.workspace = true
 spki.workspace = true
 alloy.workspace = true
 prost-types.workspace = true
--- 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
@@ -45,13 +45,11 @@ insert into arbiter_settings (id) values (1) on conflict do nothing;

 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),
    created_at integer not null default(unixepoch ('now')),
    updated_at integer not null default(unixepoch ('now'))
 ) STRICT;
-create unique index if not exists uniq_useragent_client_public_key on useragent_client (public_key, key_type);
+create unique index if not exists uniq_useragent_client_public_key on useragent_client (public_key);

 create table if not exists client_metadata (
    id integer not null primary key,
@@ -73,7 +71,6 @@ create unique index if not exists uniq_metadata_binding_client on client_metadat

 create table if not exists program_client (
    id integer not null primary key,
-    nonce integer not null default(1), -- used for auth challenge
    public_key blob not null,
    metadata_id integer not null references client_metadata (id) on delete cascade,
    created_at integer not null default(unixepoch ('now')),
--- a/server/crates/arbiter-server/src/actors/bootstrap.rs
+++ b/server/crates/arbiter-server/src/actors/bootstrap.rs
@@ -1,13 +1,13 @@
+use crate::db::{self, DatabasePool, schema};
 use arbiter_proto::{BOOTSTRAP_PATH, home_path};
+
 use diesel::QueryDsl;
 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};
 const TOKEN_LENGTH: usize = 64;

 pub async fn generate_token() -> Result<String, std::io::Error> {
--- a/server/crates/arbiter-server/src/actors/evm/mod.rs
+++ b/server/crates/arbiter-server/src/actors/evm/mod.rs
@@ -1,11 +1,3 @@
-use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
-use diesel::{
-    ExpressionMethods, OptionalExtension as _, QueryDsl, SelectableHelper as _, dsl::insert_into,
-};
-use diesel_async::RunQueryDsl;
-use kameo::{Actor, actor::ActorRef, messages};
-use rand::{SeedableRng, rng, rngs::StdRng};
-
 use crate::{
    actors::vault::{CreateNew, Decrypt, Vault},
    crypto::integrity,
@@ -24,6 +16,14 @@ use crate::{
 };
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

+use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
+use diesel::{
+    ExpressionMethods, OptionalExtension as _, QueryDsl, SelectableHelper as _, dsl::insert_into,
+};
+use diesel_async::RunQueryDsl;
+use kameo::{Actor, actor::ActorRef, messages};
+use rand::{SeedableRng, rng, rngs::StdRng};
+
 pub use crate::evm::safe_signer;

 #[derive(Debug, thiserror::Error)]
--- a/server/crates/arbiter-server/src/actors/flow_coordinator/client_connect_approval.rs
+++ b/server/crates/arbiter-server/src/actors/flow_coordinator/client_connect_approval.rs
@@ -1,11 +1,3 @@
-use std::ops::ControlFlow;
-
-use kameo::{
-    Actor, messages,
-    prelude::{ActorId, ActorRef, ActorStopReason, Context, WeakActorRef},
-    reply::ReplySender,
-};
-
 use crate::{
    actors::flow_coordinator::ApprovalError,
    peers::{
@@ -14,6 +6,13 @@ use crate::{
    },
 };

+use kameo::{
+    Actor, messages,
+    prelude::{ActorId, ActorRef, ActorStopReason, Context, WeakActorRef},
+    reply::ReplySender,
+};
+use std::ops::ControlFlow;
+
 pub struct Args {
    pub client: ClientProfile,
    pub user_agents: Vec<ActorRef<UserAgentSession>>,
--- a/server/crates/arbiter-server/src/actors/flow_coordinator/mod.rs
+++ b/server/crates/arbiter-server/src/actors/flow_coordinator/mod.rs
@@ -1,4 +1,10 @@
-use std::{collections::HashMap, ops::ControlFlow};
+use crate::{
+    actors::{
+        flow_coordinator::client_connect_approval::ClientApprovalController,
+        useragent_registry::{GetConnected, UserAgentRegistry},
+    },
+    peers::client::{ClientProfile, session::ClientSession},
+};

 use kameo::{
    Actor,
@@ -7,22 +13,23 @@ use kameo::{
    prelude::{ActorStopReason, Context, WeakActorRef},
    reply::DelegatedReply,
 };
+use std::{collections::HashMap, ops::ControlFlow};
 use tracing::info;

-use crate::{
-    actors::flow_coordinator::client_connect_approval::ClientApprovalController,
-    peers::{
-        client::{ClientProfile, session::ClientSession},
-        user_agent::UserAgentSession,
-    },
-};
-
 pub mod client_connect_approval;

-#[derive(Default)]
 pub struct FlowCoordinator {
-    pub user_agents: HashMap<ActorId, ActorRef<UserAgentSession>>,
    pub clients: HashMap<ActorId, ActorRef<ClientSession>>,
+    useragent_registry: ActorRef<UserAgentRegistry>,
+}
+
+impl FlowCoordinator {
+    pub fn new(useragent_registry: ActorRef<UserAgentRegistry>) -> Self {
+        Self {
+            clients: HashMap::default(),
+            useragent_registry,
+        }
+    }
 }

 impl Actor for FlowCoordinator {
@@ -40,13 +47,7 @@ impl Actor for FlowCoordinator {
        id: ActorId,
        _: ActorStopReason,
    ) -> Result<ControlFlow<ActorStopReason>, Self::Error> {
-        if self.user_agents.remove(&id).is_some() {
-            info!(
-                ?id,
-                actor = "FlowCoordinator",
-                event = "useragent.disconnected"
-            );
-        } else if self.clients.remove(&id).is_some() {
+        if self.clients.remove(&id).is_some() {
            info!(
                ?id,
                actor = "FlowCoordinator",
@@ -71,17 +72,6 @@ pub enum ApprovalError {

 #[messages]
 impl FlowCoordinator {
-    #[message(ctx)]
-    pub async fn register_user_agent(
-        &mut self,
-        actor: ActorRef<UserAgentSession>,
-        ctx: &mut Context<Self, ()>,
-    ) {
-        info!(id = %actor.id(), actor = "FlowCoordinator", event = "useragent.connected");
-        ctx.actor_ref().link(&actor).await;
-        self.user_agents.insert(actor.id(), actor);
-    }
-
    #[message(ctx)]
    pub async fn register_client(
        &mut self,
@@ -103,7 +93,14 @@ impl FlowCoordinator {
            unreachable!("Expected `request_client_approval` to have callback channel");
        };

-        let refs: Vec<_> = self.user_agents.values().cloned().collect();
+        let refs = match self.useragent_registry.ask(GetConnected).await {
+            Ok(refs) => refs,
+            Err(_) => {
+                reply_sender.send(Err(ApprovalError::NoUserAgentsConnected));
+                return reply;
+            }
+        };
+
        if refs.is_empty() {
            reply_sender.send(Err(ApprovalError::NoUserAgentsConnected));
            return reply;
--- a/server/crates/arbiter-server/src/actors/mod.rs
+++ b/server/crates/arbiter-server/src/actors/mod.rs
@@ -1,19 +1,20 @@
-use kameo::actor::{ActorRef, Spawn};
-use kameo_actors::{DeliveryStrategy, message_bus::MessageBus};
-use thiserror::Error;
-
 use crate::{
    actors::{
-        bootstrap::Bootstrapper, evm::EvmActor, flow_coordinator::FlowCoordinator, vault::Vault,
+        bootstrap::Bootstrapper, evm::EvmActor, flow_coordinator::FlowCoordinator,
+        useragent_registry::UserAgentRegistry, vault::Vault,
    },
    db,
 };

+use kameo::actor::{ActorRef, Spawn};
+use kameo_actors::{DeliveryStrategy, message_bus::MessageBus};
+use thiserror::Error;
+
 pub mod bootstrap;
 pub mod evm;
 pub mod flow_coordinator;
-pub mod vault;
 pub mod useragent_registry;
+pub mod vault;

 #[derive(Error, Debug)]
 pub enum SpawnError {
@@ -30,6 +31,7 @@ pub struct GlobalActors {
    pub vault: ActorRef<Vault>,
    pub bootstrapper: ActorRef<Bootstrapper>,
    pub flow_coordinator: ActorRef<FlowCoordinator>,
+    pub useragent_registry: ActorRef<UserAgentRegistry>,
    pub evm: ActorRef<EvmActor>,
    pub events: ActorRef<MessageBus>,
 }
@@ -42,11 +44,15 @@ impl GlobalActors {
    pub async fn spawn(db: db::DatabasePool) -> Result<Self, SpawnError> {
        let message_bus = Self::spawn_message_bus();
        let key_holder = Vault::spawn(Vault::new(db.clone(), message_bus.clone()).await?);
+        let useragent_registry = UserAgentRegistry::spawn(UserAgentRegistry::default());
        Ok(Self {
            bootstrapper: Bootstrapper::spawn(Bootstrapper::new(&db).await?),
            evm: EvmActor::spawn(EvmActor::new(key_holder.clone(), db)),
            vault: key_holder,
-            flow_coordinator: FlowCoordinator::spawn(FlowCoordinator::default()),
+            flow_coordinator: FlowCoordinator::spawn(FlowCoordinator::new(
+                useragent_registry.clone(),
+            )),
+            useragent_registry,
            events: message_bus,
        })
    }
--- a/server/crates/arbiter-server/src/actors/useragent_registry.rs
+++ b/server/crates/arbiter-server/src/actors/useragent_registry.rs
@@ -1,57 +1,61 @@
-use alloy::primitives::map::HashMap;
-use arbiter_crypto::authn;
-use kameo::{error::Infallible, prelude::*};
+use crate::peers::user_agent::UserAgentSession;

-use crate::{db::DatabasePool, peers::user_agent::{Credentials, UserAgentSession}};
-
-use super::vault::{Vault, events as vault_events};
-
-pub struct Args {
-    pub vault: ActorRef<Vault>,
-    pub pool: DatabasePool,
-}
+use kameo::{
+    Actor,
+    actor::{ActorId, ActorRef},
+    error::Infallible,
+    messages,
+    prelude::{ActorStopReason, Context, WeakActorRef},
+};
+use std::{collections::HashMap, ops::ControlFlow};
+use tracing::info;

+#[derive(Default)]
 pub struct UserAgentRegistry {
-    vault: ActorRef<Vault>,
-    pool: DatabasePool,
-    connected: HashMap<Credentials, ActorRef<UserAgentSession>>,
+    connected: HashMap<ActorId, ActorRef<UserAgentSession>>,
 }

-impl Message<vault_events::Bootstrapped> for UserAgentRegistry {
-    type Reply = ();
-
-    async fn handle(
-        &mut self,
-        msg: vault_events::Bootstrapped,
-        ctx: &mut Context<Self, Self::Reply>,
-    ) -> Self::Reply {
-        todo!()
-    }
-}
-
-impl Message<vault_events::Unsealed> for UserAgentRegistry {
-    type Reply = ();
-
-    async fn handle(
-        &mut self,
-        msg: vault_events::Unsealed,
-        ctx: &mut Context<Self, Self::Reply>,
-    ) -> Self::Reply {
-        todo!()
-    }
-}
 impl Actor for UserAgentRegistry {
-    type Args = Args;
+    type Args = Self;

    type Error = Infallible;

-    async fn on_start(args: Self::Args, actor_ref: ActorRef<Self>) -> Result<Self, Self::Error> {
-        Ok(Self {
-            vault: args.vault,
-            pool: args.pool,
-            connected: HashMap::default(),
-        })
+    async fn on_start(args: Self::Args, _: ActorRef<Self>) -> Result<Self, Self::Error> {
+        Ok(args)
    }

-    
+    async fn on_link_died(
+        &mut self,
+        _: WeakActorRef<Self>,
+        id: ActorId,
+        _: ActorStopReason,
+    ) -> Result<ControlFlow<ActorStopReason>, Self::Error> {
+        if self.connected.remove(&id).is_some() {
+            info!(
+                ?id,
+                actor = "UserAgentRegistry",
+                event = "useragent.disconnected"
+            );
+        }
+        Ok(ControlFlow::Continue(()))
+    }
+}
+
+#[messages]
+impl UserAgentRegistry {
+    #[message(ctx)]
+    pub async fn connect_useragent(
+        &mut self,
+        actor: ActorRef<UserAgentSession>,
+        ctx: &mut Context<Self, ()>,
+    ) {
+        info!(id = %actor.id(), actor = "UserAgentRegistry", event = "useragent.connected");
+        ctx.actor_ref().link(&actor).await;
+        self.connected.insert(actor.id(), actor);
+    }
+
+    #[message]
+    pub fn get_connected(&self) -> Vec<ActorRef<UserAgentSession>> {
+        self.connected.values().cloned().collect()
+    }
 }
--- a/server/crates/arbiter-server/src/actors/vault/mod.rs
+++ b/server/crates/arbiter-server/src/actors/vault/mod.rs
@@ -1,3 +1,17 @@
+use crate::{
+    crypto::{
+        KeyCell, derive_key,
+        encryption::v1::{self, Nonce},
+        integrity::v1::HmacSha256,
+    },
+    db::{
+        self,
+        models::{self, RootKeyHistory},
+        schema::{self},
+    },
+};
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+
 use chrono::Utc;
 use diesel::{
    ExpressionMethods as _, OptionalExtension, QueryDsl, SelectableHelper,
@@ -10,18 +24,6 @@ use kameo_actors::message_bus::{MessageBus, Publish};
 use strum::{EnumDiscriminants, IntoDiscriminant};
 use tracing::{error, info};

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

    #[derive(Clone, Copy)]
@@ -213,7 +215,7 @@ impl Vault {
        });

        info!("Vault bootstrapped successfully");
-        self.events.tell(Publish(events::Bootstrapped)).await;
+        let _ = self.events.tell(Publish(events::Bootstrapped)).await;

        Ok(())
    }
@@ -269,7 +271,7 @@ impl Vault {
        });

        info!("Vault unsealed successfully");
-        self.events.tell(Publish(events::Unsealed)).await;
+        let _ = self.events.tell(Publish(events::Unsealed)).await;

        Ok(())
    }
@@ -399,7 +401,7 @@ impl Vault {
        self.state = State::Sealed {
            root_key_history_id: *root_key_history_id,
        };
-        self.events.tell(Publish(events::VaultResealed)).await;
+        let _ = self.events.tell(Publish(events::VaultResealed)).await;
        Ok(())
    }
 }
--- a/server/crates/arbiter-server/src/context/mod.rs
+++ b/server/crates/arbiter-server/src/context/mod.rs
@@ -1,13 +1,12 @@
-use std::sync::Arc;
-
-use thiserror::Error;
-
 use crate::{
    actors::GlobalActors,
    context::tls::TlsManager,
    db::{self},
 };

+use std::sync::Arc;
+use thiserror::Error;
+
 pub mod tls;

 #[derive(Error, Debug)]
--- a/server/crates/arbiter-server/src/context/tls.rs
+++ b/server/crates/arbiter-server/src/context/tls.rs
@@ -1,17 +1,3 @@
-use std::{net::Ipv4Addr, string::FromUtf8Error};
-
-use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper as _};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-
-use pem::Pem;
-use rcgen::{
-    BasicConstraints, Certificate, CertificateParams, CertifiedIssuer, DistinguishedName, DnType,
-    IsCa, Issuer, KeyPair, KeyUsagePurpose, SanType,
-};
-use rustls::pki_types::pem::PemObject;
-use thiserror::Error;
-use tonic::transport::CertificateDer;
-
 use crate::db::{
    self,
    models::{NewTlsHistory, TlsHistory},
@@ -21,6 +7,18 @@ use crate::db::{
    },
 };

+use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper as _};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use pem::Pem;
+use rcgen::{
+    BasicConstraints, Certificate, CertificateParams, CertifiedIssuer, DistinguishedName, DnType,
+    IsCa, Issuer, KeyPair, KeyUsagePurpose, SanType,
+};
+use rustls::pki_types::pem::PemObject;
+use std::{net::Ipv4Addr, string::FromUtf8Error};
+use thiserror::Error;
+use tonic::transport::CertificateDer;
+
 const ENCODE_CONFIG: pem::EncodeConfig = {
    let line_ending = match cfg!(target_family = "windows") {
        true => pem::LineEnding::CRLF,
--- a/server/crates/arbiter-server/src/crypto/encryption/v1.rs
+++ b/server/crates/arbiter-server/src/crypto/encryption/v1.rs
@@ -1,5 +1,4 @@
 use argon2::password_hash::Salt as ArgonSalt;
-
 use rand::{
    Rng as _, SeedableRng,
    rngs::{StdRng, SysRng},
@@ -63,7 +62,7 @@ mod tests {
    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

    #[test]
-    pub fn derive_seal_key_deterministic() {
+    fn derive_seal_key_deterministic() {
        static PASSWORD: &[u8] = b"password";
        let password = SafeCell::new(PASSWORD.to_vec());
        let password2 = SafeCell::new(PASSWORD.to_vec());
@@ -79,7 +78,7 @@ mod tests {
    }

    #[test]
-    pub fn successful_derive() {
+    fn successful_derive() {
        static PASSWORD: &[u8] = b"password";
        let password = SafeCell::new(PASSWORD.to_vec());
        let salt = generate_salt();
@@ -93,7 +92,7 @@ mod tests {

    #[test]
    // We should fuzz this
-    pub fn test_nonce_increment() {
+    fn test_nonce_increment() {
        let mut nonce = Nonce([0u8; NONCE_LENGTH]);
        nonce.increment();

--- a/server/crates/arbiter-server/src/crypto/integrity/v1.rs
+++ b/server/crates/arbiter-server/src/crypto/integrity/v1.rs
@@ -1,25 +1,18 @@
 use crate::{
-    actors::vault::{self, GetState},
-    crypto::integrity::hashing::Hashable,
-};
-use hmac::Hmac;
-use sha2::Sha256;
-
-use diesel::{ExpressionMethods as _, QueryDsl, dsl::insert_into, sqlite::Sqlite};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-use kameo::{actor::ActorRef, error::SendError};
-use sha2::Digest as _;
-
-pub mod hashing;
-
-use crate::{
-    actors::vault::{SignIntegrity, Vault, VerifyIntegrity},
+    actors::vault::{self, GetState, SignIntegrity, Vault, VerifyIntegrity},
    db::{
        self,
        models::{IntegrityEnvelope, NewIntegrityEnvelope},
        schema::integrity_envelope,
    },
 };
+use arbiter_crypto::hashing::Hashable;
+
+use diesel::{ExpressionMethods as _, QueryDsl, dsl::insert_into, sqlite::Sqlite};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use hmac::Hmac;
+use kameo::{actor::ActorRef, error::SendError};
+use sha2::{Digest as _, Sha256};

 #[derive(Debug, thiserror::Error)]
 pub enum Error {
@@ -194,9 +187,7 @@ pub async fn verify_entity<E: Integrable>(
        Ok(false) => Err(Error::MacMismatch {
            entity_kind: E::KIND,
        }),
-        Err(SendError::HandlerError(vault::Error::Sealed)) => {
-            Ok(AttestationStatus::Unavailable)
-        }
+        Err(SendError::HandlerError(vault::Error::Sealed)) => Ok(AttestationStatus::Unavailable),
        Err(_) => Err(Error::VaultSend),
    }
 }
@@ -212,8 +203,6 @@ mod tests {
    use diesel_async::RunQueryDsl;
    use kameo::{actor::ActorRef, prelude::Spawn};

-    use sha2::Digest;
-
    use crate::{
        actors::{
            GlobalActors,
@@ -223,21 +212,12 @@ mod tests {
    };
    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

-    use super::hashing::Hashable;
    use super::{Error, Integrable, sign_entity, verify_entity};
-
-    #[derive(Clone)]
+    #[derive(Clone, arbiter_macros::Hashable)]
    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";
    }
--- a/server/crates/arbiter-server/src/crypto/mod.rs
+++ b/server/crates/arbiter-server/src/crypto/mod.rs
@@ -1,4 +1,5 @@
-use std::ops::Deref as _;
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use encryption::v1::{Nonce, Salt};

 use argon2::{Algorithm, Argon2};
 use chacha20poly1305::{
@@ -9,14 +10,11 @@ use rand::{
    Rng as _, SeedableRng as _,
    rngs::{StdRng, SysRng},
 };
-
-use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use std::ops::Deref as _;

 pub mod encryption;
 pub mod integrity;

-use encryption::v1::{Nonce, Salt};
-
 pub struct KeyCell(pub SafeCell<Key>);
 impl From<SafeCell<Key>> for KeyCell {
    fn from(value: SafeCell<Key>) -> Self {
@@ -144,7 +142,7 @@ mod tests {
    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

    #[test]
-    pub fn encrypt_decrypt() {
+    fn encrypt_decrypt() {
        static PASSWORD: &[u8] = b"password";
        let password = SafeCell::new(PASSWORD.to_vec());
        let salt = generate_salt();
--- a/server/crates/arbiter-server/src/db/mod.rs
+++ b/server/crates/arbiter-server/src/db/mod.rs
@@ -5,7 +5,6 @@ use diesel_async::{
    sync_connection_wrapper::SyncConnectionWrapper,
 };
 use diesel_migrations::{EmbeddedMigrations, MigrationHarness, embed_migrations};
-
 use thiserror::Error;
 use tracing::info;

--- a/server/crates/arbiter-server/src/db/models.rs
+++ b/server/crates/arbiter-server/src/db/models.rs
@@ -1,12 +1,12 @@
 #![allow(unused)]
 #![allow(clippy::all)]
-
 use crate::db::schema::{
    self, aead_encrypted, arbiter_settings, evm_basic_grant, evm_ether_transfer_grant,
    evm_ether_transfer_grant_target, evm_ether_transfer_limit, evm_token_transfer_grant,
    evm_token_transfer_log, evm_token_transfer_volume_limit, evm_transaction_log, evm_wallet,
    integrity_envelope, root_key_history, tls_history,
 };
+
 use chrono::{DateTime, Utc};
 use diesel::{prelude::*, sqlite::Sqlite};
 use restructed::Models;
@@ -195,7 +195,6 @@ pub struct ProgramClientMetadataHistory {
 #[diesel(table_name = schema::program_client, check_for_backend(Sqlite))]
 pub struct ProgramClient {
    pub id: i32,
-    pub nonce: i32,
    pub public_key: Vec<u8>,
    pub metadata_id: i32,
    pub created_at: SqliteTimestamp,
@@ -206,7 +205,6 @@ pub struct ProgramClient {
 #[diesel(table_name = schema::useragent_client, check_for_backend(Sqlite))]
 pub struct UseragentClient {
    pub id: i32,
-    pub nonce: i32,
    pub public_key: Vec<u8>,
    pub created_at: SqliteTimestamp,
    pub updated_at: SqliteTimestamp,
--- a/server/crates/arbiter-server/src/db/schema.rs
+++ b/server/crates/arbiter-server/src/db/schema.rs
@@ -155,7 +155,6 @@ diesel::table! {
 diesel::table! {
    program_client (id) {
        id -> Integer,
-        nonce -> Integer,
        public_key -> Binary,
        metadata_id -> Integer,
        created_at -> Integer,
@@ -189,9 +188,7 @@ diesel::table! {
 diesel::table! {
    useragent_client (id) {
        id -> Integer,
-        nonce -> Integer,
        public_key -> Binary,
-        key_type -> Integer,
        created_at -> Integer,
        updated_at -> Integer,
    }
--- a/server/crates/arbiter-server/src/evm/mod.rs
+++ b/server/crates/arbiter-server/src/evm/mod.rs
@@ -1,15 +1,3 @@
-pub mod abi;
-pub mod safe_signer;
-
-use alloy::{
-    consensus::TxEip1559,
-    primitives::{TxKind, U256},
-};
-use chrono::Utc;
-use diesel::{ExpressionMethods as _, QueryDsl as _, QueryResult, insert_into, sqlite::Sqlite};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-use kameo::actor::ActorRef;
-
 use crate::{
    actors::vault::Vault,
    crypto::integrity,
@@ -27,6 +15,18 @@ use crate::{
    },
 };

+use alloy::{
+    consensus::TxEip1559,
+    primitives::{TxKind, U256},
+};
+use chrono::Utc;
+use diesel::{ExpressionMethods as _, QueryDsl as _, QueryResult, insert_into, sqlite::Sqlite};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use kameo::actor::ActorRef;
+
+pub mod abi;
+pub mod safe_signer;
+
 pub mod policies;
 mod utils;

--- a/server/crates/arbiter-server/src/evm/policies.rs
+++ b/server/crates/arbiter-server/src/evm/policies.rs
@@ -1,4 +1,8 @@
-use std::fmt::Display;
+use crate::{
+    crypto::integrity::v1::Integrable,
+    db::models::{self, EvmBasicGrant, EvmWalletAccess},
+    evm::utils,
+};

 use alloy::primitives::{Address, Bytes, ChainId, U256};
 use chrono::{DateTime, Duration, Utc};
@@ -6,15 +10,9 @@ use diesel::{
    ExpressionMethods as _, QueryDsl, SelectableHelper, result::QueryResult, sqlite::Sqlite,
 };
 use diesel_async::{AsyncConnection, RunQueryDsl};
-
+use std::fmt::Display;
 use thiserror::Error;

-use crate::{
-    crypto::integrity::v1::Integrable,
-    db::models::{self, EvmBasicGrant, EvmWalletAccess},
-    evm::utils,
-};
-
 pub mod ether_transfer;
 pub mod token_transfers;

@@ -127,19 +125,19 @@ pub enum SpecificMeaning {
    TokenTransfer(token_transfers::Meaning),
 }

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

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

-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, arbiter_macros::Hashable)]
 pub struct SharedGrantSettings {
    pub wallet_access_id: i32,
    pub chain: ChainId,
@@ -200,7 +198,7 @@ pub enum SpecificGrant {
    TokenTransfer(token_transfers::Settings),
 }

-#[derive(Debug)]
+#[derive(Debug, arbiter_macros::Hashable)]
 pub struct CombinedSettings<PolicyGrant> {
    pub shared: SharedGrantSettings,
    pub specific: PolicyGrant,
@@ -219,38 +217,3 @@ impl<P: Integrable> Integrable for CombinedSettings<P> {
    const KIND: &'static str = P::KIND;
    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
@@ -1,30 +1,33 @@
-use std::collections::HashMap;
-use std::fmt::Display;
-
-use alloy::primitives::{Address, U256};
-use chrono::{DateTime, Duration, Utc};
-use diesel::dsl::{auto_type, insert_into};
-use diesel::sqlite::Sqlite;
-use diesel::{ExpressionMethods, JoinOnDsl, prelude::*};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-
-use crate::crypto::integrity::v1::Integrable;
-use crate::db::models::{
-    EvmBasicGrant, EvmEtherTransferGrant, EvmEtherTransferGrantTarget, EvmEtherTransferLimit,
-    NewEvmEtherTransferLimit, SqliteTimestamp,
-};
-use crate::db::schema::{evm_basic_grant, evm_ether_transfer_limit, evm_transaction_log};
-use crate::evm::policies::{
-    CombinedSettings, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning, VolumeRateLimit,
-};
+use super::{DatabaseID, EvalContext, EvalViolation};
 use crate::{
+    crypto::integrity::v1::Integrable,
+    db::models::{
+        EvmBasicGrant, EvmEtherTransferGrant, EvmEtherTransferGrantTarget, EvmEtherTransferLimit,
+        NewEvmEtherTransferLimit, SqliteTimestamp,
+    },
+    db::schema::{evm_basic_grant, evm_ether_transfer_limit, evm_transaction_log},
    db::{
        models::{self, NewEvmEtherTransferGrant, NewEvmEtherTransferGrantTarget},
        schema::{evm_ether_transfer_grant, evm_ether_transfer_grant_target},
    },
+    evm::policies::{
+        CombinedSettings, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning,
+        VolumeRateLimit,
+    },
    evm::{policies::Policy, utils},
 };

+use alloy::primitives::{Address, U256};
+use chrono::{DateTime, Duration, Utc};
+use diesel::{
+    ExpressionMethods, JoinOnDsl,
+    dsl::{auto_type, insert_into},
+    prelude::*,
+    sqlite::Sqlite,
+};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use std::{collections::HashMap, fmt::Display};
+
 #[auto_type]
 fn grant_join() -> _ {
    evm_ether_transfer_grant::table.inner_join(
@@ -32,8 +35,6 @@ fn grant_join() -> _ {
    )
 }

-use super::{DatabaseID, EvalContext, EvalViolation};
-
 // Plain ether transfer
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub struct Meaning {
@@ -52,7 +53,7 @@ impl From<Meaning> for SpecificMeaning {
 }

 // A grant for ether transfers, which can be scoped to specific target addresses and volume limits
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, arbiter_macros::Hashable)]
 pub struct Settings {
    pub target: Vec<Address>,
    pub limit: VolumeRateLimit,
@@ -61,15 +62,6 @@ 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
@@ -1,25 +1,26 @@
+use super::{EtherTransfer, Settings};
+use crate::{
+    db::{
+        self, DatabaseConnection,
+        models::{
+            EvmBasicGrant, EvmWalletAccess, NewEvmBasicGrant, NewEvmTransactionLog, SqliteTimestamp,
+        },
+        schema::{evm_basic_grant, evm_transaction_log},
+    },
+    evm::{
+        policies::{
+            CombinedSettings, EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings,
+            VolumeRateLimit,
+        },
+        utils,
+    },
+};
+
 use alloy::primitives::{Address, Bytes, U256, address};
 use chrono::{Duration, Utc};
 use diesel::{SelectableHelper, insert_into};
 use diesel_async::RunQueryDsl;

-use crate::db::{
-    self, DatabaseConnection,
-    models::{
-        EvmBasicGrant, EvmWalletAccess, NewEvmBasicGrant, NewEvmTransactionLog, SqliteTimestamp,
-    },
-    schema::{evm_basic_grant, evm_transaction_log},
-};
-use crate::evm::{
-    policies::{
-        CombinedSettings, EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings,
-        VolumeRateLimit,
-    },
-    utils,
-};
-
-use super::{EtherTransfer, Settings};
-
 const WALLET_ACCESS_ID: i32 = 1;
 const CHAIN_ID: u64 = 1;

@@ -340,7 +341,7 @@ proptest::proptest! {
    ) {
        use rand::{SeedableRng, seq::SliceRandom};
        use sha2::Digest;
-        use crate::crypto::integrity::hashing::Hashable;
+        use arbiter_crypto::hashing::Hashable;

        let addrs: Vec<Address> = raw_addrs.iter().map(|b| Address::from(*b)).collect();
        let mut shuffled = addrs.clone();
--- a/server/crates/arbiter-server/src/evm/policies/token_transfers/mod.rs
+++ b/server/crates/arbiter-server/src/evm/policies/token_transfers/mod.rs
@@ -1,16 +1,4 @@
-use std::collections::HashMap;
-
-use crate::db::schema::{
-    evm_basic_grant, evm_token_transfer_grant, evm_token_transfer_log,
-    evm_token_transfer_volume_limit,
-};
-use crate::evm::{
-    abi::IERC20::transferCall,
-    policies::{
-        Grant, Policy, SharedGrantSettings, SpecificGrant, SpecificMeaning, VolumeRateLimit,
-    },
-    utils,
-};
+use super::{DatabaseID, EvalContext, EvalViolation};
 use crate::{
    crypto::integrity::Integrable,
    db::models::{
@@ -18,20 +6,34 @@ use crate::{
        NewEvmTokenTransferGrant, NewEvmTokenTransferLog, NewEvmTokenTransferVolumeLimit,
        SqliteTimestamp,
    },
+    db::schema::{
+        evm_basic_grant, evm_token_transfer_grant, evm_token_transfer_log,
+        evm_token_transfer_volume_limit,
+    },
    evm::policies::CombinedSettings,
+    evm::{
+        abi::IERC20::transferCall,
+        policies::{
+            Grant, Policy, SharedGrantSettings, SpecificGrant, SpecificMeaning, VolumeRateLimit,
+        },
+        utils,
+    },
 };
+use arbiter_tokens_registry::evm::nonfungible::{self, TokenInfo};
+
 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::{
+    ExpressionMethods,
+    dsl::{auto_type, insert_into},
+    prelude::*,
+    sqlite::Sqlite,
+};
 use diesel_async::{AsyncConnection, RunQueryDsl};
-
-use super::{DatabaseID, EvalContext, EvalViolation};
+use std::collections::HashMap;

 #[auto_type]
 fn grant_join() -> _ {
@@ -62,7 +64,7 @@ impl From<Meaning> for SpecificMeaning {
 }

 // A grant for token transfers, which can be scoped to specific target addresses and volume limits
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, arbiter_macros::Hashable)]
 pub struct Settings {
    pub token_contract: Address,
    pub target: Option<Address>,
@@ -72,16 +74,6 @@ 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
@@ -1,25 +1,28 @@
-use alloy::primitives::{Address, Bytes, U256, address};
-use alloy::sol_types::SolCall;
+use super::{Settings, TokenTransfer};
+use crate::{
+    db::{
+        self, DatabaseConnection,
+        models::{EvmBasicGrant, EvmWalletAccess, NewEvmBasicGrant, SqliteTimestamp},
+        schema::evm_basic_grant,
+    },
+    evm::{
+        abi::IERC20::transferCall,
+        policies::{
+            CombinedSettings, EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings,
+            VolumeRateLimit,
+        },
+        utils,
+    },
+};
+
+use alloy::{
+    primitives::{Address, Bytes, U256, address},
+    sol_types::SolCall,
+};
 use chrono::{Duration, Utc};
 use diesel::{SelectableHelper, insert_into};
 use diesel_async::RunQueryDsl;

-use crate::db::{
-    self, DatabaseConnection,
-    models::{EvmBasicGrant, EvmWalletAccess, NewEvmBasicGrant, SqliteTimestamp},
-    schema::evm_basic_grant,
-};
-use crate::evm::{
-    abi::IERC20::transferCall,
-    policies::{
-        CombinedSettings, EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings,
-        VolumeRateLimit,
-    },
-    utils,
-};
-
-use super::{Settings, TokenTransfer};
-
 // DAI on Ethereum mainnet — present in the static token registry
 const CHAIN_ID: u64 = 1;
 const DAI: Address = address!("6B175474E89094C44Da98b954EedeAC495271d0F");
@@ -419,7 +422,7 @@ proptest::proptest! {
    ) {
        use rand::{SeedableRng, seq::SliceRandom};
        use sha2::Digest;
-        use crate::crypto::integrity::hashing::Hashable;
+        use arbiter_crypto::hashing::Hashable;

        let limits: Vec<VolumeRateLimit> = raw_limits
            .iter()
--- a/server/crates/arbiter-server/src/evm/safe_signer.rs
+++ b/server/crates/arbiter-server/src/evm/safe_signer.rs
@@ -1,4 +1,4 @@
-use std::sync::Mutex;
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};

 use alloy::{
    consensus::SignableTransaction,
@@ -6,9 +6,9 @@ use alloy::{
    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};
+use std::sync::Mutex;

 /// An Ethereum signer that stores its secp256k1 secret key inside a
 /// hardware-protected [`MemSafe`] cell.
--- a/server/crates/arbiter-server/src/evm/utils.rs
+++ b/server/crates/arbiter-server/src/evm/utils.rs
@@ -2,20 +2,20 @@ use alloy::primitives::U256;

 #[derive(thiserror::Error, Debug)]
 #[error("Expected {expected} bytes but got {actual} bytes")]
-pub struct LengthError {
-    pub expected: usize,
-    pub actual: usize,
+pub(super) struct LengthError {
+    pub(super) expected: usize,
+    pub(super) actual: usize,
 }

-pub fn u256_to_bytes(value: U256) -> [u8; 32] {
+pub(super) fn u256_to_bytes(value: U256) -> [u8; 32] {
    value.to_le_bytes()
 }
-pub fn bytes_to_u256(bytes: &[u8]) -> Option<U256> {
+pub(super) fn bytes_to_u256(bytes: &[u8]) -> Option<U256> {
    let bytes: [u8; 32] = bytes.try_into().ok()?;
    Some(U256::from_le_bytes(bytes))
 }

-pub fn try_bytes_to_u256(bytes: &[u8]) -> diesel::result::QueryResult<U256> {
+pub(super) fn try_bytes_to_u256(bytes: &[u8]) -> diesel::result::QueryResult<U256> {
    let bytes: [u8; 32] = bytes.try_into().map_err(|_| {
        diesel::result::Error::DeserializationError(Box::new(LengthError {
            expected: 32,
--- a/server/crates/arbiter-server/src/grpc/client.rs
+++ b/server/crates/arbiter-server/src/grpc/client.rs
@@ -1,3 +1,7 @@
+use crate::{
+    grpc::request_tracker::RequestTracker,
+    peers::client::{ClientConnection, session::ClientSession},
+};
 use arbiter_proto::{
    proto::client::{
        ClientRequest, ClientResponse, client_request::Payload as ClientRequestPayload,
@@ -5,15 +9,11 @@ use arbiter_proto::{
    },
    transport::{Receiver, Sender, grpc::GrpcBi},
 };
+
 use kameo::actor::{ActorRef, Spawn as _};
 use tonic::Status;
 use tracing::{info, warn};

-use crate::{
-    grpc::request_tracker::RequestTracker,
-    peers::client::{ClientConnection, session::ClientSession},
-};
-
 mod auth;
 mod evm;
 mod inbound;
--- a/server/crates/arbiter-server/src/grpc/client/auth.rs
+++ b/server/crates/arbiter-server/src/grpc/client/auth.rs
@@ -1,3 +1,7 @@
+use crate::{
+    grpc::request_tracker::RequestTracker,
+    peers::client::{self, ClientConnection, auth},
+};
 use arbiter_crypto::authn;
 use arbiter_proto::{
    ClientMetadata,
@@ -17,22 +21,18 @@ use arbiter_proto::{
    },
    transport::{Bi, Error as TransportError, Receiver, Sender, grpc::GrpcBi},
 };
+
 use async_trait::async_trait;
 use tonic::Status;
 use tracing::warn;

-use crate::{
-    grpc::request_tracker::RequestTracker,
-    peers::client::{self, ClientConnection, auth},
-};
-
-pub struct AuthTransportAdapter<'a> {
+pub(super) struct AuthTransportAdapter<'a> {
    bi: &'a mut GrpcBi<ClientRequest, ClientResponse>,
    request_tracker: &'a mut RequestTracker,
 }

 impl<'a> AuthTransportAdapter<'a> {
-    pub fn new(
+    pub(super) fn new(
        bi: &'a mut GrpcBi<ClientRequest, ClientResponse>,
        request_tracker: &'a mut RequestTracker,
    ) -> Self {
@@ -44,10 +44,14 @@ impl<'a> AuthTransportAdapter<'a> {

    fn response_to_proto(response: auth::Outbound) -> AuthResponsePayload {
        match response {
-            auth::Outbound::AuthChallenge { pubkey, nonce } => {
+            auth::Outbound::AuthChallenge { challenge } => {
                AuthResponsePayload::Challenge(ProtoAuthChallenge {
-                    pubkey: pubkey.to_bytes(),
-                    nonce,
+                    timestamp_nanos: challenge
+                        .timestamp
+                        .timestamp_nanos_opt()
+                        .expect("timestamp within range")
+                        as u64,
+                    random: challenge.nonce.to_vec(),
                })
            }
            auth::Outbound::AuthSuccess => {
@@ -193,7 +197,7 @@ fn client_metadata_from_proto(metadata: ProtoClientInfo) -> ClientMetadata {
    }
 }

-pub async fn start(
+pub(super) async fn start(
    conn: &mut ClientConnection,
    bi: &mut GrpcBi<ClientRequest, ClientResponse>,
    request_tracker: &mut RequestTracker,
--- a/server/crates/arbiter-server/src/grpc/client/evm.rs
+++ b/server/crates/arbiter-server/src/grpc/client/evm.rs
@@ -1,3 +1,10 @@
+use crate::{
+    grpc::{
+        Convert, TryConvert,
+        common::inbound::{RawEvmAddress, RawEvmTransaction},
+    },
+    peers::client::session::{ClientSession, HandleSignTransaction, SignTransactionRpcError},
+};
 use arbiter_proto::proto::{
    client::{
        client_response::Payload as ClientResponsePayload,
@@ -11,18 +18,11 @@ use arbiter_proto::proto::{
        evm_sign_transaction_response::Result as EvmSignTransactionResult,
    },
 };
+
 use kameo::actor::ActorRef;
 use tonic::Status;
 use tracing::warn;

-use crate::{
-    grpc::{
-        Convert, TryConvert,
-        common::inbound::{RawEvmAddress, RawEvmTransaction},
-    },
-    peers::client::session::{ClientSession, HandleSignTransaction, SignTransactionRpcError},
-};
-
 fn wrap_response(payload: EvmResponsePayload) -> ClientResponsePayload {
    ClientResponsePayload::Evm(proto_evm::Response {
        payload: Some(payload),
--- a/server/crates/arbiter-server/src/grpc/client/vault.rs
+++ b/server/crates/arbiter-server/src/grpc/client/vault.rs
@@ -1,3 +1,7 @@
+use crate::{
+    actors::vault::VaultState,
+    peers::client::session::{ClientSession, Error, HandleQueryVaultState},
+};
 use arbiter_proto::proto::{
    client::{
        client_response::Payload as ClientResponsePayload,
@@ -8,15 +12,11 @@ use arbiter_proto::proto::{
    },
    shared::VaultState as ProtoVaultState,
 };
+
 use kameo::{actor::ActorRef, error::SendError};
 use tonic::Status;
 use tracing::warn;

-use crate::{
-    actors::vault::VaultState,
-    peers::client::session::{ClientSession, Error, HandleQueryVaultState},
-};
-
 pub(super) async fn dispatch(
    actor: &ActorRef<ClientSession>,
    req: proto_vault::Request,
--- a/server/crates/arbiter-server/src/grpc/common.rs
+++ b/server/crates/arbiter-server/src/grpc/common.rs
@@ -1,2 +1,2 @@
-pub mod inbound;
-pub mod outbound;
+pub(super) mod inbound;
+pub(super) mod outbound;
--- a/server/crates/arbiter-server/src/grpc/common/inbound.rs
+++ b/server/crates/arbiter-server/src/grpc/common/inbound.rs
@@ -1,8 +1,8 @@
-use alloy::{consensus::TxEip1559, primitives::Address, rlp::Decodable as _};
-
 use crate::grpc::TryConvert;

-pub struct RawEvmAddress(pub Vec<u8>);
+use alloy::{consensus::TxEip1559, primitives::Address, rlp::Decodable as _};
+
+pub(in crate::grpc) struct RawEvmAddress(pub(in crate::grpc) Vec<u8>);
 impl TryConvert for RawEvmAddress {
    type Output = Address;

@@ -21,7 +21,7 @@ impl TryConvert for RawEvmAddress {
    }
 }

-pub struct RawEvmTransaction(pub Vec<u8>);
+pub(in crate::grpc) struct RawEvmTransaction(pub(in crate::grpc) Vec<u8>);
 impl TryConvert for RawEvmTransaction {
    type Output = TxEip1559;

--- a/server/crates/arbiter-server/src/grpc/common/outbound.rs
+++ b/server/crates/arbiter-server/src/grpc/common/outbound.rs
@@ -1,4 +1,10 @@
-use alloy::primitives::U256;
+use crate::{
+    evm::{
+        PolicyError, VetError,
+        policies::{EvalViolation, SpecificMeaning},
+    },
+    grpc::Convert,
+};
 use arbiter_proto::proto::{
    evm::{
        EvmError as ProtoEvmError,
@@ -14,13 +20,7 @@ use arbiter_proto::proto::{
    },
 };

-use crate::{
-    evm::{
-        PolicyError, VetError,
-        policies::{EvalViolation, SpecificMeaning},
-    },
-    grpc::Convert,
-};
+use alloy::primitives::U256;

 fn u256_to_proto_bytes(value: U256) -> Vec<u8> {
    value.to_be_bytes::<32>().to_vec()
--- a/server/crates/arbiter-server/src/grpc/mod.rs
+++ b/server/crates/arbiter-server/src/grpc/mod.rs
@@ -1,3 +1,4 @@
+use crate::peers::{client::ClientConnection, user_agent::UserAgentConnection};
 use arbiter_proto::{
    proto::{
        client::{ClientRequest, ClientResponse},
@@ -5,14 +6,11 @@ use arbiter_proto::{
    },
    transport::grpc::GrpcBi,
 };
+
 use tokio_stream::wrappers::ReceiverStream;
 use tonic::{Request, Response, Status, async_trait};
 use tracing::info;

-use crate::{
-    peers::{client::ClientConnection, user_agent::UserAgentConnection},
-};
-
 mod request_tracker;

 pub mod client;
--- a/server/crates/arbiter-server/src/grpc/request_tracker.rs
+++ b/server/crates/arbiter-server/src/grpc/request_tracker.rs
@@ -1,12 +1,12 @@
 use tonic::Status;

 #[derive(Default)]
-pub struct RequestTracker {
+pub(super) struct RequestTracker {
    next_request_id: i32,
 }

 impl RequestTracker {
-    pub fn request(&mut self, id: i32) -> Result<i32, Status> {
+    pub(super) fn request(&mut self, id: i32) -> Result<i32, Status> {
        if id < self.next_request_id {
            return Err(Status::invalid_argument("Duplicate request id"));
        }
@@ -20,7 +20,7 @@ impl RequestTracker {

    // This is used to set the response id for auth responses, which need to match the request id of the auth challenge request.
    // -1 offset is needed because request() increments the next_request_id after returning the current request id.
-    pub fn current_request_id(&self) -> i32 {
+    pub(super) fn current_request_id(&self) -> i32 {
        self.next_request_id - 1
    }
 }
--- a/server/crates/arbiter-server/src/grpc/user_agent.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent.rs
@@ -1,5 +1,7 @@
-use tokio::sync::{mpsc, oneshot};
-
+use crate::{
+    grpc::request_tracker::RequestTracker,
+    peers::user_agent::{OutOfBand, UserAgentConnection, UserAgentSession},
+};
 use arbiter_proto::{
    proto::user_agent::{
        UserAgentRequest, UserAgentResponse,
@@ -8,20 +10,13 @@ use arbiter_proto::{
    },
    transport::{Error as TransportError, Receiver, Sender, grpc::GrpcBi},
 };
+
 use async_trait::async_trait;
-use kameo::actor::{ActorRef, Spawn as _};
+use kameo::actor::ActorRef;
+use tokio::sync::mpsc;
 use tonic::Status;
 use tracing::{error, info, warn};

-use crate::{
-    crypto::integrity,
-    grpc::request_tracker::RequestTracker,
-    peers::user_agent::{
-        Credentials, OutOfBand, UserAgentConnection, UserAgentSession,
-        vault_gate::VaultGate,
-    },
-};
-
 mod auth;
 mod evm;
 mod inbound;
@@ -129,115 +124,22 @@ pub async fn start(
 ) {
    let mut request_tracker = RequestTracker::default();

-    let auth_creds = match auth::start(&mut conn, &mut bi, &mut request_tracker).await {
-        Ok(creds) => creds,
-        Err(e) => {
-            warn!(error = ?e, "Authentication failed");
-            return;
-        }
-    };
-
-    info!(pubkey = ?auth_creds.creds.pubkey, "User authenticated successfully");
-
-    let creds = if integrity::is_signing_available(&conn.actors.vault)
-        .await
-        .unwrap_or(false)
-    {
-        // Vault is unsealed; integrity was verified during auth — promote directly.
-        auth_creds.creds
-    } else {
-        // Vault is sealed/unbootstrapped; run the VaultGate phase.
-        let (promotion_tx, promotion_rx) = oneshot::channel();
-        let gate = VaultGate::spawn(VaultGate::new(
-            auth_creds,
-            conn.actors.clone(),
-            conn.db.clone(),
-            promotion_tx,
-        ));
-
-        let result = vault_gate_loop(&mut bi, &gate, &mut request_tracker, promotion_rx).await;
-        gate.kill();
-
-        match result {
-            Some(creds) => creds,
-            None => return,
-        }
-    };
-
    let (oob_sender, oob_receiver) = mpsc::channel(16);
    let oob_adapter = OutOfBandAdapter(oob_sender);

-    let actor = UserAgentSession::spawn(UserAgentSession::new(conn, creds, Box::new(oob_adapter)));
-    let actor_for_cleanup = actor.clone();
-
-    dispatch_loop(bi, actor, oob_receiver, request_tracker).await;
-    actor_for_cleanup.kill();
-}
-
-async fn vault_gate_loop(
-    bi: &mut GrpcBi<UserAgentRequest, UserAgentResponse>,
-    gate: &ActorRef<VaultGate>,
-    request_tracker: &mut RequestTracker,
-    mut promotion_rx: oneshot::Receiver<Result<Credentials, crate::peers::user_agent::vault_gate::Error>>,
-) -> Option<Credentials> {
-    loop {
-        tokio::select! {
-            result = &mut promotion_rx => {
-                return match result {
-                    Ok(Ok(creds)) => Some(creds),
-                    Ok(Err(e)) => {
-                        warn!(error = ?e, "VaultGate promotion failed");
-                        None
-                    }
-                    Err(_) => {
-                        warn!("VaultGate promotion channel closed unexpectedly");
-                        None
-                    }
-                };
-            }
-
-            message = bi.recv() => {
-                let Some(message) = message else { return None; };
-
-                let conn = match message {
-                    Ok(conn) => conn,
-                    Err(err) => {
-                        warn!(error = ?err, "Failed to receive request during vault gate phase");
-                        return None;
-                    }
-                };
-
-                let request_id = match request_tracker.request(conn.id) {
-                    Ok(id) => id,
-                    Err(err) => {
-                        let _ = bi.send(Err(err)).await;
-                        return None;
-                    }
-                };
-
-                let Some(payload) = conn.payload else {
-                    let _ = bi.send(Err(Status::invalid_argument("Missing request payload"))).await;
-                    return None;
-                };
-
-                let response = match payload {
-                    UserAgentRequestPayload::Vault(req) => vault_gate::dispatch(gate, req).await,
-                    _ => Err(Status::permission_denied("Only vault operations are permitted before unsealing")),
-                };
-
-                match response {
-                    Ok(Some(payload)) => {
-                        if bi.send(Ok(UserAgentResponse { id: Some(request_id), payload: Some(payload) })).await.is_err() {
-                            return None;
-                        }
-                    }
-                    Ok(None) => {}
-                    Err(status) => {
-                        let _ = bi.send(Err(status)).await;
-                        return None;
-                    }
-                }
+    let actor = {
+        let transport = auth::AuthTransportAdapter::new(&mut bi, &mut request_tracker);
+        match crate::peers::user_agent::start(&mut conn, transport, Box::new(oob_adapter)).await {
+            Ok(actor) => actor,
+            Err(e) => {
+                warn!(error = ?e, "User agent connection failed");
+                return;
            }
        }
-    }
+    };
+
+    info!("User agent session established");
+
+    dispatch_loop(bi, actor.clone(), oob_receiver, request_tracker).await;
+    actor.kill();
 }
--- 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 crate::{grpc::request_tracker::RequestTracker, peers::user_agent::auth};
 use arbiter_crypto::authn;
 use arbiter_proto::{
    proto::user_agent::{
@@ -13,22 +14,18 @@ use arbiter_proto::{
    },
    transport::{Bi, Error as TransportError, Receiver, Sender, grpc::GrpcBi},
 };
+
 use async_trait::async_trait;
 use tonic::Status;
 use tracing::warn;

-use crate::{
-    grpc::request_tracker::RequestTracker,
-    peers::user_agent::{AuthCredentials, UserAgentConnection, auth},
-};
-
-pub struct AuthTransportAdapter<'a> {
+pub(super) struct AuthTransportAdapter<'a> {
    pub(super) bi: &'a mut GrpcBi<UserAgentRequest, UserAgentResponse>,
    pub(super) request_tracker: &'a mut RequestTracker,
 }

 impl<'a> AuthTransportAdapter<'a> {
-    pub fn new(
+    pub(super) fn new(
        bi: &'a mut GrpcBi<UserAgentRequest, UserAgentResponse>,
        request_tracker: &'a mut RequestTracker,
    ) -> Self {
@@ -77,8 +74,15 @@ impl Sender<Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {
    ) -> Result<(), TransportError> {
        use auth::{Error, Outbound};
        let payload = match item {
-            Ok(Outbound::AuthChallenge { nonce }) => {
-                AuthResponsePayload::Challenge(ProtoAuthChallenge { nonce })
+            Ok(Outbound::AuthChallenge { challenge }) => {
+                AuthResponsePayload::Challenge(ProtoAuthChallenge {
+                    timestamp_nanos: challenge
+                        .timestamp
+                        .timestamp_nanos_opt()
+                        .expect("timestamp within range")
+                        as u64,
+                    random: challenge.nonce.to_vec(),
+                })
            }
            Ok(Outbound::AuthSuccess) => {
                AuthResponsePayload::Result(ProtoAuthResult::Success.into())
@@ -178,12 +182,3 @@ impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
 }

 impl Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {}
-
-pub async fn start(
-    conn: &mut UserAgentConnection,
-    bi: &mut GrpcBi<UserAgentRequest, UserAgentResponse>,
-    request_tracker: &mut RequestTracker,
-) -> Result<AuthCredentials, auth::Error> {
-    let mut transport = AuthTransportAdapter::new(bi, request_tracker);
-    auth::authenticate(conn, &mut transport).await
-}
--- a/server/crates/arbiter-server/src/grpc/user_agent/evm.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/evm.rs
@@ -1,3 +1,17 @@
+use crate::{
+    grpc::{
+        Convert, TryConvert,
+        common::inbound::{RawEvmAddress, RawEvmTransaction},
+    },
+    peers::user_agent::{
+        UserAgentSession,
+        session::handlers::{
+            GrantMutationError, HandleEvmWalletCreate, HandleEvmWalletList, HandleGrantCreate,
+            HandleGrantDelete, HandleGrantList, HandleSignTransaction,
+            SignTransactionError as SessionSignTransactionError,
+        },
+    },
+};
 use arbiter_proto::proto::{
    evm::{
        EvmError as ProtoEvmError, EvmGrantCreateRequest, EvmGrantCreateResponse,
@@ -18,25 +32,11 @@ use arbiter_proto::proto::{
        user_agent_response::Payload as UserAgentResponsePayload,
    },
 };
+
 use kameo::actor::ActorRef;
 use tonic::Status;
 use tracing::warn;

-use crate::{
-    grpc::{
-        Convert, TryConvert,
-        common::inbound::{RawEvmAddress, RawEvmTransaction},
-    },
-    peers::user_agent::{
-        UserAgentSession,
-        session::handlers::{
-            GrantMutationError, HandleEvmWalletCreate, HandleEvmWalletList, HandleGrantCreate,
-            HandleGrantDelete, HandleGrantList, HandleSignTransaction,
-            SignTransactionError as SessionSignTransactionError,
-        },
-    },
-};
-
 fn wrap_evm_response(payload: EvmResponsePayload) -> UserAgentResponsePayload {
    UserAgentResponsePayload::Evm(proto_evm::Response {
        payload: Some(payload),
--- a/server/crates/arbiter-server/src/grpc/user_agent/inbound.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/inbound.rs
@@ -1,26 +1,26 @@
-use alloy::primitives::{Address, U256};
-use arbiter_proto::proto::evm::{
-    EtherTransferSettings as ProtoEtherTransferSettings, SharedSettings as ProtoSharedSettings,
-    SpecificGrant as ProtoSpecificGrant, TokenTransferSettings as ProtoTokenTransferSettings,
-    TransactionRateLimit as ProtoTransactionRateLimit, VolumeRateLimit as ProtoVolumeRateLimit,
-    specific_grant::Grant as ProtoSpecificGrantType,
-};
-use arbiter_proto::proto::user_agent::sdk_client::{
-    WalletAccess, WalletAccessEntry as SdkClientWalletAccess,
-};
-use chrono::{DateTime, TimeZone, Utc};
-use prost_types::Timestamp as ProtoTimestamp;
-use tonic::Status;
-
-use crate::db::models::{CoreEvmWalletAccess, NewEvmWalletAccess};
-use crate::grpc::Convert;
 use crate::{
+    db::models::{CoreEvmWalletAccess, NewEvmWalletAccess},
    evm::policies::{
        SharedGrantSettings, SpecificGrant, TransactionRateLimit, VolumeRateLimit, ether_transfer,
        token_transfers,
    },
+    grpc::Convert,
    grpc::TryConvert,
 };
+use arbiter_proto::{
+    proto::evm::{
+        EtherTransferSettings as ProtoEtherTransferSettings, SharedSettings as ProtoSharedSettings,
+        SpecificGrant as ProtoSpecificGrant, TokenTransferSettings as ProtoTokenTransferSettings,
+        TransactionRateLimit as ProtoTransactionRateLimit, VolumeRateLimit as ProtoVolumeRateLimit,
+        specific_grant::Grant as ProtoSpecificGrantType,
+    },
+    proto::user_agent::sdk_client::{WalletAccess, WalletAccessEntry as SdkClientWalletAccess},
+};
+
+use alloy::primitives::{Address, U256};
+use chrono::{DateTime, TimeZone, Utc};
+use prost_types::Timestamp as ProtoTimestamp;
+use tonic::Status;

 fn address_from_bytes(bytes: Vec<u8>) -> Result<Address, Status> {
    if bytes.len() != 20 {
--- a/server/crates/arbiter-server/src/grpc/user_agent/outbound.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/outbound.rs
@@ -1,3 +1,8 @@
+use crate::{
+    db::models::EvmWalletAccess,
+    evm::policies::{SharedGrantSettings, SpecificGrant, TransactionRateLimit, VolumeRateLimit},
+    grpc::Convert,
+};
 use arbiter_proto::proto::{
    evm::{
        EtherTransferSettings as ProtoEtherTransferSettings, SharedSettings as ProtoSharedSettings,
@@ -7,15 +12,10 @@ use arbiter_proto::proto::{
    },
    user_agent::sdk_client::{WalletAccess, WalletAccessEntry as ProtoSdkClientWalletAccess},
 };
+
 use chrono::{DateTime, Utc};
 use prost_types::Timestamp as ProtoTimestamp;

-use crate::{
-    db::models::EvmWalletAccess,
-    evm::policies::{SharedGrantSettings, SpecificGrant, TransactionRateLimit, VolumeRateLimit},
-    grpc::Convert,
-};
-
 impl Convert for DateTime<Utc> {
    type Output = ProtoTimestamp;

--- 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 +1,14 @@
+use crate::{
+    db::models::NewEvmWalletAccess,
+    grpc::Convert,
+    peers::user_agent::{
+        OutOfBand, UserAgentSession,
+        session::handlers::{
+            HandleGrantEvmWalletAccess, HandleListWalletAccess, HandleNewClientApprove,
+            HandleRevokeEvmWalletAccess, HandleSdkClientList,
+        },
+    },
+};
 use arbiter_crypto::authn;
 use arbiter_proto::proto::{
    shared::ClientInfo as ProtoClientMetadata,
@@ -16,22 +27,11 @@ use arbiter_proto::proto::{
        user_agent_response::Payload as UserAgentResponsePayload,
    },
 };
+
 use kameo::actor::ActorRef;
 use tonic::Status;
 use tracing::{info, warn};

-use crate::{
-    db::models::NewEvmWalletAccess,
-    grpc::Convert,
-    peers::user_agent::{
-        OutOfBand, UserAgentSession,
-        session::handlers::{
-            HandleGrantEvmWalletAccess, HandleListWalletAccess, HandleNewClientApprove,
-            HandleRevokeEvmWalletAccess, HandleSdkClientList,
-        },
-    },
-};
-
 fn wrap_sdk_client_response(payload: SdkClientResponsePayload) -> UserAgentResponsePayload {
    UserAgentResponsePayload::SdkClient(proto_sdk_client::Response {
        payload: Some(payload),
--- a/server/crates/arbiter-server/src/grpc/user_agent/vault.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/vault.rs
@@ -1,16 +1,21 @@
-use arbiter_proto::proto::shared::VaultState as ProtoVaultState;
-use arbiter_proto::proto::user_agent::{
-    user_agent_response::Payload as UserAgentResponsePayload,
-    vault::{self as proto_vault, request::Payload as VaultRequestPayload, response::Payload as VaultResponsePayload},
-};
-use kameo::actor::ActorRef;
-use tonic::Status;
-use tracing::warn;
-
 use crate::{
    actors::vault::VaultState,
    peers::user_agent::{UserAgentSession, session::handlers::HandleQueryVaultState},
 };
+use arbiter_proto::{
+    proto::shared::VaultState as ProtoVaultState,
+    proto::user_agent::{
+        user_agent_response::Payload as UserAgentResponsePayload,
+        vault::{
+            self as proto_vault, request::Payload as VaultRequestPayload,
+            response::Payload as VaultResponsePayload,
+        },
+    },
+};
+
+use kameo::actor::ActorRef;
+use tonic::Status;
+use tracing::warn;

 fn wrap_vault_response(payload: VaultResponsePayload) -> UserAgentResponsePayload {
    UserAgentResponsePayload::Vault(proto_vault::Response {
--- a/server/crates/arbiter-server/src/grpc/user_agent/vault_gate.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/vault_gate.rs
@@ -1,57 +1,16 @@
-use arbiter_proto::{
-    proto::user_agent::{
-        user_agent_request::Payload as UserAgentRequestPayload,
-        user_agent_response::Payload as UserAgentResponsePayload,
-        vault::{
-            self as proto_vault,
-            bootstrap::{self as proto_bootstrap, BootstrapResult as ProtoBootstrapResult},
-            request::Payload as VaultRequestPayload,
-            response::Payload as VaultResponsePayload,
-            unseal::{
-                self as proto_unseal, UnsealResult as ProtoUnsealResult,
-                request::Payload as UnsealRequestPayload,
-                response::Payload as UnsealResponsePayload,
-            },
-        },
-    },
-    transport::{Bi, Error as TransportError, Receiver, Sender},
+use super::auth::AuthTransportAdapter;
+use crate::{
+    grpc::TryConvert,
+    peers::user_agent::vault_gate::{self as vault_gate},
 };
+use arbiter_proto::transport::{Bi, Error as TransportError, Receiver, Sender};
+
 use async_trait::async_trait;
 use tonic::Status;
 use tracing::warn;

-use super::auth::AuthTransportAdapter;
-use crate::peers::user_agent::vault_gate::{
-    self as vault_gate, HandleBootstrapEncryptedKey, HandleHandshake, HandleUnsealEncryptedKey,
-};
-
-fn wrap_vault_response(payload: VaultResponsePayload) -> UserAgentResponsePayload {
-    UserAgentResponsePayload::Vault(proto_vault::Response {
-        payload: Some(payload),
-    })
-}
-
-fn wrap_unseal_response(payload: UnsealResponsePayload) -> UserAgentResponsePayload {
-    wrap_vault_response(VaultResponsePayload::Unseal(proto_unseal::Response {
-        payload: Some(payload),
-    }))
-}
-
-fn wrap_bootstrap_response(result: ProtoBootstrapResult) -> UserAgentResponsePayload {
-    wrap_vault_response(VaultResponsePayload::Bootstrap(proto_bootstrap::Response {
-        result: result.into(),
-    }))
-}
-
-impl AuthTransportAdapter<'_> {
-    async fn send_query_state(&mut self) -> Result<(), TransportError> {
-        use arbiter_proto::proto::shared::VaultState as ProtoVaultState;
-        self.send_response_payload(wrap_vault_response(VaultResponsePayload::State(
-            ProtoVaultState::Sealed.into(),
-        )))
-        .await
-    }
-}
+mod inbound;
+mod outbound;

 #[async_trait]
 impl Receiver<vault_gate::Inbound> for AuthTransportAdapter<'_> {
@@ -60,7 +19,10 @@ impl Receiver<vault_gate::Inbound> for AuthTransportAdapter<'_> {
            let request = match self.bi_mut().recv().await? {
                Ok(request) => request,
                Err(error) => {
-                    warn!(?error, "Failed to receive user agent request during vault gate");
+                    warn!(
+                        ?error,
+                        "Failed to receive user agent request during vault gate"
+                    );
                    return None;
                }
            };
@@ -78,86 +40,12 @@ impl Receiver<vault_gate::Inbound> for AuthTransportAdapter<'_> {
                return None;
            };

-            let vault_req = match payload {
-                UserAgentRequestPayload::Vault(req) => req,
-                _ => {
-                    let _ = self
-                        .bi_mut()
-                        .send(Err(Status::permission_denied(
-                            "Only vault operations are permitted before unsealing",
-                        )))
-                        .await;
+            match payload.try_convert() {
+                Ok(inbound) => return Some(inbound),
+                Err(status) => {
+                    let _ = self.bi_mut().send(Err(status)).await;
                    return None;
                }
-            };
-
-            let Some(vault_payload) = vault_req.payload else {
-                let _ = self
-                    .bi_mut()
-                    .send(Err(Status::invalid_argument("Missing vault request payload")))
-                    .await;
-                return None;
-            };
-
-            match vault_payload {
-                VaultRequestPayload::QueryState(_) => {
-                    if self.send_query_state().await.is_err() {
-                        return None;
-                    }
-                    continue;
-                }
-                VaultRequestPayload::Unseal(req) => {
-                    let Some(unseal_payload) = req.payload else {
-                        let _ = self
-                            .bi_mut()
-                            .send(Err(Status::invalid_argument("Missing unseal request payload")))
-                            .await;
-                        return None;
-                    };
-                    match unseal_payload {
-                        UnsealRequestPayload::Start(start) => {
-                            let Ok(bytes) = <[u8; 32]>::try_from(start.client_pubkey) else {
-                                let _ = self
-                                    .bi_mut()
-                                    .send(Err(Status::invalid_argument(
-                                        "Invalid X25519 public key",
-                                    )))
-                                    .await;
-                                return None;
-                            };
-                            return Some(vault_gate::Inbound::HandleHandshake(HandleHandshake {
-                                client_pubkey: x25519_dalek::PublicKey::from(bytes),
-                            }));
-                        }
-                        UnsealRequestPayload::EncryptedKey(key) => {
-                            return Some(vault_gate::Inbound::HandleUnsealEncryptedKey(
-                                HandleUnsealEncryptedKey {
-                                    nonce: key.nonce,
-                                    ciphertext: key.ciphertext,
-                                    associated_data: key.associated_data,
-                                },
-                            ));
-                        }
-                    }
-                }
-                VaultRequestPayload::Bootstrap(req) => {
-                    let Some(encrypted_key) = req.encrypted_key else {
-                        let _ = self
-                            .bi_mut()
-                            .send(Err(Status::invalid_argument(
-                                "Missing bootstrap encrypted key",
-                            )))
-                            .await;
-                        return None;
-                    };
-                    return Some(vault_gate::Inbound::HandleBootstrapEncryptedKey(
-                        HandleBootstrapEncryptedKey {
-                            nonce: encrypted_key.nonce,
-                            ciphertext: encrypted_key.ciphertext,
-                            associated_data: encrypted_key.associated_data,
-                        },
-                    ));
-                }
            }
        }
    }
@@ -180,55 +68,10 @@ impl Sender<Result<vault_gate::Outbound, vault_gate::Error>> for AuthTransportAd
            }
        };

-        let payload = match outbound {
-            vault_gate::Outbound::HandleHandshake(Ok(response)) => {
-                wrap_unseal_response(UnsealResponsePayload::Start(
-                    proto_unseal::UnsealStartResponse {
-                        server_pubkey: response.server_pubkey.as_bytes().to_vec(),
-                    },
-                ))
-            }
-            vault_gate::Outbound::HandleHandshake(Err(err)) => {
-                warn!(?err, "handshake failed");
-                return self
-                    .bi_mut()
-                    .send(Err(Status::internal("Failed to start unseal flow")))
-                    .await;
-            }
-            vault_gate::Outbound::HandleUnsealEncryptedKey(result) => {
-                let proto_result = match result {
-                    Ok(()) => ProtoUnsealResult::Success,
-                    Err(vault_gate::Error::InvalidKey) => ProtoUnsealResult::InvalidKey,
-                    Err(err) => {
-                        warn!(?err, "unseal failed");
-                        return self
-                            .bi_mut()
-                            .send(Err(Status::internal("Failed to unseal vault")))
-                            .await;
-                    }
-                };
-                wrap_unseal_response(UnsealResponsePayload::Result(proto_result.into()))
-            }
-            vault_gate::Outbound::HandleBootstrapEncryptedKey(result) => {
-                let proto_result = match result {
-                    Ok(()) => ProtoBootstrapResult::Success,
-                    Err(vault_gate::Error::InvalidKey) => ProtoBootstrapResult::InvalidKey,
-                    Err(vault_gate::Error::AlreadyBootstrapped) => {
-                        ProtoBootstrapResult::AlreadyBootstrapped
-                    }
-                    Err(err) => {
-                        warn!(?err, "bootstrap failed");
-                        return self
-                            .bi_mut()
-                            .send(Err(Status::internal("Failed to bootstrap vault")))
-                            .await;
-                    }
-                };
-                wrap_bootstrap_response(proto_result)
-            }
-        };
-
-        self.send_response_payload(payload).await
+        match outbound.try_convert() {
+            Ok(payload) => self.send_response_payload(payload).await,
+            Err(status) => self.bi_mut().send(Err(status)).await,
+        }
    }
 }

--- a/server/crates/arbiter-server/src/grpc/user_agent/vault_gate/inbound.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/vault_gate/inbound.rs
@@ -0,0 +1,129 @@
+use crate::{
+    grpc::{Convert, TryConvert},
+    peers::user_agent::vault_gate::{
+        self as vault_gate, HandleBootstrapEncryptedKey, HandleHandshake, HandleUnsealEncryptedKey,
+    },
+};
+use arbiter_proto::proto::user_agent::{
+    user_agent_request::Payload as UserAgentRequestPayload,
+    vault::{
+        self as proto_vault,
+        bootstrap::{self as proto_bootstrap},
+        request::Payload as VaultRequestPayload,
+        unseal::{self as proto_unseal, request::Payload as UnsealRequestPayload},
+    },
+};
+
+use tonic::Status;
+
+impl TryConvert for UserAgentRequestPayload {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        match self {
+            UserAgentRequestPayload::Vault(req) => req.try_convert(),
+            _ => Err(Status::permission_denied(
+                "Only vault operations are permitted before unsealing",
+            )),
+        }
+    }
+}
+
+impl TryConvert for proto_vault::Request {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        self.payload
+            .ok_or_else(|| Status::invalid_argument("Missing vault request payload"))?
+            .try_convert()
+    }
+}
+
+impl TryConvert for VaultRequestPayload {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        match self {
+            VaultRequestPayload::QueryState(_) => Ok(vault_gate::Inbound::HandleVaultState),
+            VaultRequestPayload::Unseal(req) => req.try_convert(),
+            VaultRequestPayload::Bootstrap(req) => req.try_convert(),
+        }
+    }
+}
+
+impl TryConvert for proto_unseal::Request {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        self.payload
+            .ok_or_else(|| Status::invalid_argument("Missing unseal request payload"))?
+            .try_convert()
+    }
+}
+
+impl TryConvert for UnsealRequestPayload {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        match self {
+            UnsealRequestPayload::Start(start) => start.try_convert(),
+            UnsealRequestPayload::EncryptedKey(key) => Ok(key.convert()),
+        }
+    }
+}
+
+impl TryConvert for proto_unseal::UnsealStart {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        let bytes = <[u8; 32]>::try_from(self.client_pubkey)
+            .map_err(|_| Status::invalid_argument("Invalid X25519 public key"))?;
+        Ok(vault_gate::Inbound::HandleHandshake(HandleHandshake {
+            client_pubkey: x25519_dalek::PublicKey::from(bytes),
+        }))
+    }
+}
+
+impl Convert for proto_unseal::UnsealEncryptedKey {
+    type Output = vault_gate::Inbound;
+
+    fn convert(self) -> vault_gate::Inbound {
+        vault_gate::Inbound::HandleUnsealEncryptedKey(HandleUnsealEncryptedKey {
+            nonce: self.nonce,
+            ciphertext: self.ciphertext,
+            associated_data: self.associated_data,
+        })
+    }
+}
+
+impl TryConvert for proto_bootstrap::Request {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        self.encrypted_key
+            .ok_or_else(|| Status::invalid_argument("Missing bootstrap encrypted key"))?
+            .try_convert()
+    }
+}
+
+impl TryConvert for proto_bootstrap::BootstrapEncryptedKey {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        Ok(vault_gate::Inbound::HandleBootstrapEncryptedKey(
+            HandleBootstrapEncryptedKey {
+                nonce: self.nonce,
+                ciphertext: self.ciphertext,
+                associated_data: self.associated_data,
+            },
+        ))
+    }
+}
--- a/server/crates/arbiter-server/src/grpc/user_agent/vault_gate/outbound.rs
+++ b/server/crates/arbiter-server/src/grpc/user_agent/vault_gate/outbound.rs
@@ -0,0 +1,115 @@
+use crate::{
+    actors::vault::VaultState,
+    grpc::{Convert, TryConvert},
+    peers::user_agent::vault_gate::{self as vault_gate},
+};
+use arbiter_proto::proto::{
+    shared::VaultState as ProtoVaultState,
+    user_agent::{
+        user_agent_response::Payload as UserAgentResponsePayload,
+        vault::{
+            self as proto_vault,
+            bootstrap::{self as proto_bootstrap, BootstrapResult as ProtoBootstrapResult},
+            response::Payload as VaultResponsePayload,
+            unseal::{
+                self as proto_unseal, UnsealResult as ProtoUnsealResult,
+                response::Payload as UnsealResponsePayload,
+            },
+        },
+    },
+};
+
+use tonic::Status;
+use tracing::warn;
+
+fn wrap_vault_response(payload: VaultResponsePayload) -> UserAgentResponsePayload {
+    UserAgentResponsePayload::Vault(proto_vault::Response {
+        payload: Some(payload),
+    })
+}
+
+fn wrap_unseal_response(payload: UnsealResponsePayload) -> UserAgentResponsePayload {
+    wrap_vault_response(VaultResponsePayload::Unseal(proto_unseal::Response {
+        payload: Some(payload),
+    }))
+}
+
+fn wrap_bootstrap_response(result: ProtoBootstrapResult) -> UserAgentResponsePayload {
+    wrap_vault_response(VaultResponsePayload::Bootstrap(proto_bootstrap::Response {
+        result: result.into(),
+    }))
+}
+
+impl Convert for VaultState {
+    type Output = UserAgentResponsePayload;
+
+    fn convert(self) -> UserAgentResponsePayload {
+        let proto_state = match self {
+            VaultState::Unbootstrapped => ProtoVaultState::Unbootstrapped,
+            VaultState::Sealed => ProtoVaultState::Sealed,
+            VaultState::Unsealed => ProtoVaultState::Unsealed,
+        };
+        wrap_vault_response(VaultResponsePayload::State(proto_state.into()))
+    }
+}
+
+impl Convert for vault_gate::HandshakeResponse {
+    type Output = UserAgentResponsePayload;
+
+    fn convert(self) -> UserAgentResponsePayload {
+        wrap_unseal_response(UnsealResponsePayload::Start(
+            proto_unseal::UnsealStartResponse {
+                server_pubkey: self.server_pubkey.as_bytes().to_vec(),
+            },
+        ))
+    }
+}
+
+impl TryConvert for vault_gate::Outbound {
+    type Output = UserAgentResponsePayload;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<UserAgentResponsePayload, Status> {
+        match self {
+            vault_gate::Outbound::HandleVaultState(result) => result
+                .map_err(|err| {
+                    warn!(?err, "vault state query failed");
+                    Status::internal("Failed to query vault state")
+                })
+                .map(VaultState::convert),
+            vault_gate::Outbound::HandleHandshake(result) => result
+                .map_err(|err| {
+                    warn!(?err, "handshake failed");
+                    Status::internal("Failed to start unseal flow")
+                })
+                .map(vault_gate::HandshakeResponse::convert),
+            vault_gate::Outbound::HandleUnsealEncryptedKey(result) => {
+                let proto_result = match result {
+                    Ok(()) => ProtoUnsealResult::Success,
+                    Err(vault_gate::Error::InvalidKey) => ProtoUnsealResult::InvalidKey,
+                    Err(err) => {
+                        warn!(?err, "unseal failed");
+                        return Err(Status::internal("Failed to unseal vault"));
+                    }
+                };
+                Ok(wrap_unseal_response(UnsealResponsePayload::Result(
+                    proto_result.into(),
+                )))
+            }
+            vault_gate::Outbound::HandleBootstrapEncryptedKey(result) => {
+                let proto_result = match result {
+                    Ok(()) => ProtoBootstrapResult::Success,
+                    Err(vault_gate::Error::InvalidKey) => ProtoBootstrapResult::InvalidKey,
+                    Err(vault_gate::Error::AlreadyBootstrapped) => {
+                        ProtoBootstrapResult::AlreadyBootstrapped
+                    }
+                    Err(err) => {
+                        warn!(?err, "bootstrap failed");
+                        return Err(Status::internal("Failed to bootstrap vault"));
+                    }
+                };
+                Ok(wrap_bootstrap_response(proto_result))
+            }
+        }
+    }
+}
--- a/server/crates/arbiter-server/src/main.rs
+++ b/server/crates/arbiter-server/src/main.rs
@@ -1,9 +1,9 @@
-use std::net::SocketAddr;
-
-use anyhow::anyhow;
 use arbiter_proto::{proto::arbiter_service_server::ArbiterServiceServer, url::ArbiterUrl};
 use arbiter_server::{Server, actors::bootstrap::GetToken, context::ServerContext, db};
+
+use anyhow::anyhow;
 use rustls::crypto::aws_lc_rs;
+use std::net::SocketAddr;
 use tonic::transport::{Identity, ServerTlsConfig};
 use tracing::info;

--- a/server/crates/arbiter-server/src/peers/client/auth.rs
+++ b/server/crates/arbiter-server/src/peers/client/auth.rs
@@ -1,17 +1,4 @@
-use arbiter_crypto::authn::{self, CLIENT_CONTEXT};
-use arbiter_proto::{
-    ClientMetadata,
-    transport::{Bi, expect_message},
-};
-use chrono::Utc;
-use diesel::{
-    ExpressionMethods as _, OptionalExtension as _, QueryDsl as _, SelectableHelper as _,
-    dsl::insert_into, update,
-};
-use diesel_async::RunQueryDsl as _;
-use kameo::{actor::ActorRef, error::SendError};
-use tracing::error;
-
+use super::{ClientConnection, ClientCredentials, ClientProfile};
 use crate::{
    actors::{
        GlobalActors,
@@ -25,8 +12,20 @@ use crate::{
        schema::program_client,
    },
 };
+use arbiter_crypto::authn::{self, AuthChallenge, CLIENT_CONTEXT};
+use arbiter_proto::{
+    ClientMetadata,
+    transport::{Bi, expect_message},
+};

-use super::{ClientConnection, ClientCredentials, ClientProfile};
+use chrono::Utc;
+use diesel::{
+    ExpressionMethods as _, OptionalExtension as _, QueryDsl as _, SelectableHelper as _,
+    dsl::insert_into, update,
+};
+use diesel_async::RunQueryDsl as _;
+use kameo::{actor::ActorRef, error::SendError};
+use tracing::error;

 #[derive(thiserror::Error, Debug, Clone, PartialEq, Eq)]
 pub enum Error {
@@ -74,19 +73,14 @@ pub enum Inbound {

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

-/// 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(
+async fn get_client_id(
    db: &db::DatabasePool,
    pubkey: &authn::PublicKey,
-) -> Result<Option<(i32, i32)>, Error> {
+) -> Result<Option<i32>, Error> {
    let pubkey_bytes = pubkey.to_bytes();
    let mut conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
@@ -94,8 +88,8 @@ async fn get_current_nonce_and_id(
    })?;
    program_client::table
        .filter(program_client::public_key.eq(&pubkey_bytes))
-        .select((program_client::id, program_client::nonce))
-        .first::<(i32, i32)>(&mut conn)
+        .select(program_client::id)
+        .first::<i32>(&mut conn)
        .await
        .optional()
        .map_err(|e| {
@@ -114,7 +108,7 @@ async fn verify_integrity(
        Error::DatabasePoolUnavailable
    })?;

-    let (id, nonce) = get_current_nonce_and_id(db, pubkey).await?.ok_or_else(|| {
+    let id = get_client_id(db, pubkey).await?.ok_or_else(|| {
        error!("Client not found during integrity verification");
        Error::DatabaseOperationFailed
    })?;
@@ -124,7 +118,6 @@ async fn verify_integrity(
        vault,
        &ClientCredentials {
            pubkey: pubkey.clone(),
-            nonce,
        },
        id,
    )
@@ -142,53 +135,6 @@ async fn verify_integrity(
    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,
-    vault: &ActorRef<Vault>,
-    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");
-        Error::DatabasePoolUnavailable
-    })?;
-
-    conn.exclusive_transaction(|conn| {
-        let vault = vault.clone();
-        let pubkey = pubkey.clone();
-        Box::pin(async move {
-            let (id, new_nonce): (i32, i32) = update(program_client::table)
-                .filter(program_client::public_key.eq(&pubkey_bytes))
-                .set(program_client::nonce.eq(program_client::nonce + 1))
-                .returning((program_client::id, program_client::nonce))
-                .get_result(conn)
-                .await?;
-
-            integrity::sign_entity(
-                conn,
-                &vault,
-                &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
-}
-
 async fn approve_new_client(actors: &GlobalActors, profile: ClientProfile) -> Result<(), Error> {
    let result = actors
        .flow_coordinator
@@ -228,8 +174,6 @@ async fn insert_client(
        let vault = vault.clone();
        let pubkey = pubkey.clone();
        Box::pin(async move {
-            const NONCE_START: i32 = 1;
-
            let metadata_id = insert_into(client_metadata::table)
                .values((
                    client_metadata::name.eq(&metadata.name),
@@ -244,7 +188,6 @@ async fn insert_client(
                .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)
@@ -256,7 +199,6 @@ async fn insert_client(
                &vault,
                &ClientCredentials {
                    pubkey: pubkey.clone(),
-                    nonce: NONCE_START,
                },
                client_id,
            )
@@ -346,15 +288,14 @@ async fn sync_client_metadata(
 async fn challenge_client<T>(
    transport: &mut T,
    pubkey: authn::PublicKey,
-    nonce: i32,
+    challenge: AuthChallenge,
 ) -> Result<(), Error>
 where
    T: Bi<Inbound, Result<Outbound, Error>> + ?Sized,
 {
    transport
        .send(Ok(Outbound::AuthChallenge {
-            pubkey: pubkey.clone(),
-            nonce,
+            challenge: challenge.clone(),
        }))
        .await
        .map_err(|e| {
@@ -372,7 +313,7 @@ where
        Error::Transport
    })?;

-    if !pubkey.verify(nonce, CLIENT_CONTEXT, &signature) {
+    if !pubkey.verify(&challenge, CLIENT_CONTEXT, &signature) {
        error!("Challenge solution verification failed");
        return Err(Error::InvalidChallengeSolution);
    }
@@ -388,8 +329,8 @@ where
        return Err(Error::Transport);
    };

-    let client_id = match get_current_nonce_and_id(&props.db, &pubkey).await? {
-        Some((id, _)) => {
+    let client_id = match get_client_id(&props.db, &pubkey).await? {
+        Some(id) => {
            verify_integrity(&props.db, &props.actors.vault, &pubkey).await?;
            id
        }
@@ -407,8 +348,9 @@ where
    };

    sync_client_metadata(&props.db, client_id, &metadata).await?;
-    let challenge_nonce = create_nonce(&props.db, &props.actors.vault, &pubkey).await?;
-    challenge_client(transport, pubkey, challenge_nonce).await?;
+
+    let challenge = AuthChallenge::generate(&mut rand::rng());
+    challenge_client(transport, pubkey, challenge).await?;

    transport
        .send(Ok(Outbound::AuthSuccess))
--- a/server/crates/arbiter-server/src/peers/client/mod.rs
+++ b/server/crates/arbiter-server/src/peers/client/mod.rs
@@ -1,37 +1,28 @@
+use crate::{
+    actors::GlobalActors, crypto::integrity::Integrable, db, peers::client::session::ClientSession,
+};
 use arbiter_crypto::authn;
+use arbiter_macros::Hashable;
 use arbiter_proto::{ClientMetadata, transport::Bi};
+
 use kameo::actor::Spawn;
 use tracing::{error, info};

-use crate::{
-    actors::GlobalActors,
-    crypto::integrity::{Integrable, hashing::Hashable},
-    db,
-    peers::client::session::ClientSession,
-};
-
 #[derive(Debug, Clone)]
 pub struct ClientProfile {
    pub pubkey: authn::PublicKey,
    pub metadata: ClientMetadata,
 }

+#[derive(Hashable)]
 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,
--- a/server/crates/arbiter-server/src/peers/client/session.rs
+++ b/server/crates/arbiter-server/src/peers/client/session.rs
@@ -1,8 +1,4 @@
-use kameo::{Actor, messages};
-use tracing::error;
-
-use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
-
+use super::ClientConnection;
 use crate::{
    actors::{
        GlobalActors,
@@ -14,7 +10,9 @@ use crate::{
    evm::VetError,
 };

-use super::ClientConnection;
+use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
+use kameo::{Actor, messages};
+use tracing::error;

 pub struct ClientSession {
    props: ClientConnection,
--- a/server/crates/arbiter-server/src/peers/user_agent/auth/mod.rs
+++ b/server/crates/arbiter-server/src/peers/user_agent/auth/mod.rs
@@ -1,11 +1,11 @@
-use arbiter_crypto::authn;
+use super::{Credentials, UserAgentConnection};
+use arbiter_crypto::authn::{self, AuthChallenge};
 use arbiter_proto::transport::Bi;
+
+use state::*;
 use tracing::error;

 mod state;
-use state::*;
-
-use super::{AuthCredentials, UserAgentConnection};

 #[derive(Debug, Clone)]
 pub enum Inbound {
@@ -44,7 +44,7 @@ impl From<diesel::result::Error> for Error {

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

@@ -52,12 +52,11 @@ fn parse_auth_event(payload: Inbound) -> AuthEvents {
    match payload {
        Inbound::AuthChallengeRequest {
            pubkey,
-            bootstrap_token: None,
-        } => AuthEvents::AuthRequest(ChallengeRequest { pubkey }),
-        Inbound::AuthChallengeRequest {
+            bootstrap_token,
+        } => AuthEvents::AuthRequest(ChallengeRequest {
            pubkey,
-            bootstrap_token: Some(token),
-        } => AuthEvents::BootstrapAuthRequest(BootstrapAuthRequest { pubkey, token }),
+            bootstrap_token,
+        }),
        Inbound::AuthChallengeSolution { signature } => {
            AuthEvents::ReceivedSolution(ChallengeSolution {
                solution: signature,
@@ -69,14 +68,13 @@ fn parse_auth_event(payload: Inbound) -> AuthEvents {
 pub async fn authenticate<T>(
    props: &mut UserAgentConnection,
    transport: &mut T,
-) -> Result<AuthCredentials, Error>
+) -> Result<Credentials, Error>
 where
    T: Bi<Inbound, Result<Outbound, Error>> + Send + ?Sized,
 {
    let mut state = AuthStateMachine::new(AuthContext::new(props, transport));

    loop {
-        // `state` holds a mutable reference to `props` so we can't access it directly here
        let Some(payload) = state.context_mut().transport.recv().await else {
            return Err(Error::Transport);
        };
--- a/server/crates/arbiter-server/src/peers/user_agent/auth/state.rs
+++ b/server/crates/arbiter-server/src/peers/user_agent/auth/state.rs
@@ -1,36 +1,32 @@
-use super::super::{AuthCredentials, Credentials, UserAgentConnection};
-use arbiter_crypto::authn::{self, USERAGENT_CONTEXT};
+use super::{
+    super::{Credentials, UserAgentConnection},
+    Error,
+};
+use crate::{
+    actors::bootstrap::ConsumeToken,
+    db::{DatabasePool, schema::useragent_client},
+    peers::user_agent::auth::Outbound,
+};
+use arbiter_crypto::authn::{self, AuthChallenge, USERAGENT_CONTEXT};
 use arbiter_proto::transport::Bi;
-use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, sqlite::Sqlite, update};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-use kameo::actor::ActorRef;
+
+use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl};
+use diesel_async::RunQueryDsl;
 use tracing::error;

-use super::Error;
-use crate::peers::user_agent::auth::Outbound;
-use crate::{
-    actors::{bootstrap::ConsumeToken, vault::Vault},
-    crypto::integrity,
-    db::{DatabasePool, schema::useragent_client},
-};
-
-pub struct ChallengeRequest {
-    pub pubkey: authn::PublicKey,
+pub(super) struct ChallengeRequest {
+    pub(super) pubkey: authn::PublicKey,
+    pub(super) bootstrap_token: Option<String>,
 }

-pub struct BootstrapAuthRequest {
-    pub pubkey: authn::PublicKey,
-    pub token: String,
+pub(super) struct ChallengeContext {
+    pub(super) challenge: AuthChallenge,
+    pub(super) pubkey: authn::PublicKey,
+    pub(super) bootstrap_token: Option<String>,
 }

-pub struct ChallengeContext {
-    pub id: i32,
-    pub challenge_nonce: i32,
-    pub key: authn::PublicKey,
-}
-
-pub struct ChallengeSolution {
-    pub solution: Vec<u8>,
+pub(super) struct ChallengeSolution {
+    pub(super) solution: Vec<u8>,
 }

 smlang::statemachine!(
@@ -38,119 +34,28 @@ smlang::statemachine!(
    custom_error: true,
    transitions: {
        *Init + AuthRequest(ChallengeRequest) / async prepare_challenge = SentChallenge(ChallengeContext),
-        Init + BootstrapAuthRequest(BootstrapAuthRequest) / async verify_bootstrap_token = AuthOk(AuthCredentials),
-        SentChallenge(ChallengeContext) + ReceivedSolution(ChallengeSolution) / async verify_solution = AuthOk(AuthCredentials),
+        SentChallenge(ChallengeContext) + ReceivedSolution(ChallengeSolution) / async verify_solution = AuthOk(Credentials),
    }
 );

-const NONCE_START: i32 = 1;
-
-/// Returns the current nonce, ready to use for the challenge nonce.
-async fn get_current_nonce_and_id(
-    db: &DatabasePool,
-    key: &authn::PublicKey,
-) -> Result<(i32, i32), Error> {
-    let mut db_conn = db.get().await.map_err(|e| {
+async fn get_client_id(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<Option<i32>, Error> {
+    let mut conn = db.get().await.map_err(|e| {
        error!(error = ?e, "Database pool error");
        Error::internal("Database unavailable")
    })?;
-    db_conn
-        .exclusive_transaction(|conn| {
-            Box::pin(async move {
-                useragent_client::table
-                    .filter(useragent_client::public_key.eq(key.to_bytes()))
-                    .select((useragent_client::id, useragent_client::nonce))
-                    .first::<(i32, i32)>(conn)
-                    .await
-            })
-        })
+
+    useragent_client::table
+        .filter(useragent_client::public_key.eq(pubkey.to_bytes()))
+        .select(useragent_client::id)
+        .first::<i32>(&mut conn)
        .await
        .optional()
        .map_err(|e| {
            error!(error = ?e, "Database error");
            Error::internal("Database operation failed")
-        })?
-        .ok_or_else(|| {
-            error!(?key, "Public key not found in database");
-            Error::UnregisteredPublicKey
        })
 }

-async fn verify_integrity(
-    db: &DatabasePool,
-    vault: &ActorRef<Vault>,
-    pubkey: &authn::PublicKey,
-) -> Result<(), Error> {
-    let mut db_conn = db.get().await.map_err(|e| {
-        error!(error = ?e, "Database pool error");
-        Error::internal("Database unavailable")
-    })?;
-
-    let (id, nonce) = get_current_nonce_and_id(db, pubkey).await?;
-
-    let _result = integrity::verify_entity(
-        &mut db_conn,
-        vault,
-        &AuthCredentials {
-            creds: Credentials {
-                id,
-                pubkey: pubkey.clone(),
-            },
-            new_nonce: nonce,
-        },
-        id,
-    )
-    .await
-    .map_err(|e| {
-        error!(?e, "Integrity verification failed");
-        Error::internal("Integrity verification failed")
-    })?;
-
-    Ok(())
-}
-
-async fn compute_current_nonce(
-    conn: &mut impl AsyncConnection<Backend = Sqlite>,
-    pubkey: &authn::PublicKey,
-) -> Result<(i32, i32), Error> {
-    update(useragent_client::table)
-        .filter(useragent_client::public_key.eq(pubkey.to_bytes()))
-        .set(useragent_client::nonce.eq(useragent_client::nonce + 1))
-        .returning((useragent_client::id, useragent_client::nonce))
-        .get_result(conn)
-        .await
-        .map_err(|e| {
-            error!(error = ?e, "Database error incrementing nonce");
-            Error::internal("Database operation failed")
-        })
-}
-
-async fn resign_credentials(
-    conn: &mut impl AsyncConnection<Backend = Sqlite>,
-    vault: &ActorRef<Vault>,
-    id: i32,
-    pubkey: &authn::PublicKey,
-    new_nonce: i32,
-) -> Result<(), Error> {
-    integrity::sign_entity(
-        conn,
-        vault,
-        &AuthCredentials {
-            creds: Credentials {
-                id,
-                pubkey: pubkey.clone(),
-            },
-            new_nonce,
-        },
-        id,
-    )
-    .await
-    .map_err(|e| {
-        error!(?e, "Integrity signature update failed");
-        Error::internal("Database error")
-    })
-}
-
 async fn register_key(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<i32, Error> {
    let pubkey_bytes = pubkey.to_bytes();
    let mut conn = db.get().await.map_err(|e| {
@@ -159,10 +64,7 @@ async fn register_key(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<i3
    })?;

    let id: i32 = diesel::insert_into(useragent_client::table)
-        .values((
-            useragent_client::public_key.eq(pubkey_bytes),
-            useragent_client::nonce.eq(NONCE_START),
-        ))
+        .values((useragent_client::public_key.eq(pubkey_bytes),))
        .returning(useragent_client::id)
        .get_result(&mut conn)
        .await
@@ -174,13 +76,13 @@ async fn register_key(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<i3
    Ok(id)
 }

-pub struct AuthContext<'a, T: ?Sized> {
+pub(super) struct AuthContext<'a, T: ?Sized> {
    pub(super) conn: &'a mut UserAgentConnection,
    pub(super) transport: &'a mut T,
 }

 impl<'a, T: ?Sized> AuthContext<'a, T> {
-    pub fn new(conn: &'a mut UserAgentConnection, transport: &'a mut T) -> Self {
+    pub(super) fn new(conn: &'a mut UserAgentConnection, transport: &'a mut T) -> Self {
        Self { conn, transport }
    }
 }
@@ -193,38 +95,25 @@ where

    async fn prepare_challenge(
        &mut self,
-        ChallengeRequest { pubkey }: ChallengeRequest,
+        ChallengeRequest {
+            pubkey,
+            bootstrap_token,
+        }: ChallengeRequest,
    ) -> Result<ChallengeContext, Self::Error> {
-        let is_signing = integrity::is_signing_available(&self.conn.actors.vault)
-            .await
-            .unwrap_or(false);
-
-        if is_signing {
-            verify_integrity(&self.conn.db, &self.conn.actors.vault, &pubkey).await?;
+        // Verify pubkey is registered (unless bootstrapping)
+        if bootstrap_token.is_none() {
+            let id = get_client_id(&self.conn.db, &pubkey).await?;
+            if id.is_none() {
+                return Err(Error::UnregisteredPublicKey);
+            }
        }

-        let vault = self.conn.actors.vault.clone();
-        let mut conn = self.conn.db.get().await.map_err(|e| {
-            error!(error = ?e, "Database pool error");
-            Error::internal("Database unavailable")
-        })?;
-
-        let (id, nonce) = conn
-            .exclusive_transaction(|conn| {
-                let pubkey = pubkey.clone();
-                let vault = vault.clone();
-                Box::pin(async move {
-                    let (id, new_nonce) = compute_current_nonce(conn, &pubkey).await?;
-                    if is_signing {
-                        resign_credentials(conn, &vault, id, &pubkey, new_nonce).await?;
-                    }
-                    Result::<_, Error>::Ok((id, new_nonce))
-                })
-            })
-            .await?;
+        let challenge = AuthChallenge::generate(&mut rand::rng());

        self.transport
-            .send(Ok(Outbound::AuthChallenge { nonce }))
+            .send(Ok(Outbound::AuthChallenge {
+                challenge: challenge.clone(),
+            }))
            .await
            .map_err(|e| {
                error!(?e, "Failed to send auth challenge");
@@ -232,98 +121,78 @@ where
            })?;

        Ok(ChallengeContext {
-            id,
-            challenge_nonce: nonce,
-            key: pubkey,
+            challenge,
+            pubkey,
+            bootstrap_token,
        })
    }

-    #[allow(missing_docs)]
-    #[allow(clippy::result_unit_err)]
-    async fn verify_bootstrap_token(
-        &mut self,
-        BootstrapAuthRequest { pubkey, token }: BootstrapAuthRequest,
-    ) -> Result<AuthCredentials, Self::Error> {
-        let token_ok: bool = self
-            .conn
-            .actors
-            .bootstrapper
-            .ask(ConsumeToken {
-                token: token.clone(),
-            })
-            .await
-            .map_err(|e| {
-                error!(?e, "Failed to consume bootstrap token");
-                Error::internal("Failed to consume bootstrap token")
-            })?;
-
-        if !token_ok {
-            error!("Invalid bootstrap token provided");
-            return Err(Error::InvalidBootstrapToken);
-        }
-
-        match token_ok {
-            true => {
-                let id = register_key(&self.conn.db, &pubkey).await?;
-                self.transport
-                    .send(Ok(Outbound::AuthSuccess))
-                    .await
-                    .map_err(|_| Error::Transport)?;
-                Ok(AuthCredentials {
-                    creds: Credentials { id, pubkey },
-                    new_nonce: NONCE_START,
-                })
-            }
-            false => {
-                error!("Invalid bootstrap token provided");
-                self.transport
-                    .send(Err(Error::InvalidBootstrapToken))
-                    .await
-                    .map_err(|_| Error::Transport)?;
-                Err(Error::InvalidBootstrapToken)
-            }
-        }
-    }
-
    #[allow(missing_docs)]
    #[allow(clippy::unused_unit)]
    async fn verify_solution(
        &mut self,
        ChallengeContext {
-            id,
-            challenge_nonce,
-            key,
+            challenge,
+            pubkey,
+            bootstrap_token,
        }: &ChallengeContext,
        ChallengeSolution { solution }: ChallengeSolution,
-    ) -> Result<AuthCredentials, Self::Error> {
+    ) -> Result<Credentials, 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 = key.verify(*challenge_nonce, USERAGENT_CONTEXT, &signature);
+        let valid = pubkey.verify(challenge, USERAGENT_CONTEXT, &signature);

-        match valid {
-            true => {
-                self.transport
-                    .send(Ok(Outbound::AuthSuccess))
-                    .await
-                    .map_err(|_| Error::Transport)?;
-                Ok(AuthCredentials {
-                    creds: Credentials {
-                        id: *id,
-                        pubkey: key.clone(),
-                    },
-                    new_nonce: *challenge_nonce,
-                })
-            }
-            false => {
-                self.transport
-                    .send(Err(Error::InvalidChallengeSolution))
-                    .await
-                    .map_err(|_| Error::Transport)?;
-                Err(Error::InvalidChallengeSolution)
-            }
+        if !valid {
+            self.transport
+                .send(Err(Error::InvalidChallengeSolution))
+                .await
+                .map_err(|_| Error::Transport)?;
+            return Err(Error::InvalidChallengeSolution);
        }
+
+        // Resolve client id: bootstrap (consume token + register) or lookup
+        let id = match bootstrap_token {
+            Some(token) => {
+                let token_ok: bool = self
+                    .conn
+                    .actors
+                    .bootstrapper
+                    .ask(ConsumeToken {
+                        token: token.clone(),
+                    })
+                    .await
+                    .map_err(|e| {
+                        error!(?e, "Failed to consume bootstrap token");
+                        Error::internal("Failed to consume bootstrap token")
+                    })?;
+
+                if !token_ok {
+                    error!("Invalid bootstrap token provided");
+                    self.transport
+                        .send(Err(Error::InvalidBootstrapToken))
+                        .await
+                        .map_err(|_| Error::Transport)?;
+                    return Err(Error::InvalidBootstrapToken);
+                }
+
+                register_key(&self.conn.db, pubkey).await?
+            }
+            None => get_client_id(&self.conn.db, pubkey)
+                .await?
+                .ok_or(Error::UnregisteredPublicKey)?,
+        };
+
+        self.transport
+            .send(Ok(Outbound::AuthSuccess))
+            .await
+            .map_err(|_| Error::Transport)?;
+
+        Ok(Credentials {
+            id,
+            pubkey: pubkey.clone(),
+        })
    }
 }
--- a/server/crates/arbiter-server/src/peers/user_agent/mod.rs
+++ b/server/crates/arbiter-server/src/peers/user_agent/mod.rs
@@ -1,58 +1,35 @@
 use crate::{
-    actors::GlobalActors,
-    crypto::integrity::{self, Integrable},
-    db,
+    actors::{
+        GlobalActors,
+        vault::{GetState, Vault},
+    },
+    crypto::integrity::{self, AttestationStatus, Integrable},
+    db::{self, DatabaseError, DatabasePool},
    peers::client::ClientProfile,
 };
 use arbiter_crypto::authn;
-
+use arbiter_macros::Hashable;
 use arbiter_proto::transport::{Bi, Sender};
-pub use auth::authenticate;
-use kameo::actor::{ActorRef, Spawn as _};
-pub use session::UserAgentSession;
-use tokio::sync::oneshot;
-use tracing::warn;
 use vault_gate::VaultGate;

-use crate::crypto::integrity::hashing::Hashable;
+use kameo::actor::{ActorRef, Spawn as _};
+use tokio::sync::oneshot;
+use tracing::{error, warn};
+
+pub use auth::authenticate;
+pub use session::UserAgentSession;

 pub mod auth;
 pub mod session;
 pub mod vault_gate;

-#[derive(Debug, Clone, Hash)]
+#[derive(Debug, Clone, Hashable)]
 pub struct Credentials {
    pub id: i32,
    pub pubkey: authn::PublicKey,
 }
-impl Hashable for Credentials {
-    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
-        self.id.hash(hasher);
-        self.pubkey.hash(hasher);
-    }
-}

-#[derive(Debug, Clone)]
-pub struct AuthCredentials {
-    pub creds: Credentials,
-    // denotes new nonce, not current
-    pub new_nonce: i32,
-}
-
-impl Hashable for authn::PublicKey {
-    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
-        hasher.update(self.to_bytes());
-    }
-}
-
-impl Hashable for AuthCredentials {
-    fn hash<H: sha2::Digest>(&self, hasher: &mut H) {
-        self.creds.hash(hasher);
-        self.new_nonce.hash(hasher);
-    }
-}
-
-impl Integrable for AuthCredentials {
+impl Integrable for Credentials {
    const KIND: &'static str = "useragent_credentials";
 }

@@ -83,6 +60,8 @@ pub enum Error {
    VaultGate(#[from] vault_gate::Error),
    #[error("transport closed unexpectedly")]
    Transport,
+    #[error("database error: {0}")]
+    Database(DatabaseError),
    #[error("internal: {0}")]
    Internal(String),
 }
@@ -93,38 +72,44 @@ impl From<auth::Error> for Error {
    }
 }

-pub async fn start<T>(
-    props: &mut UserAgentConnection,
-    mut transport: T,
-    oob_sender: Box<dyn Sender<OutOfBand>>,
-) -> Result<ActorRef<UserAgentSession>, Error>
-where
-    T: Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> + Send,
-    T: Bi<vault_gate::Inbound, Result<vault_gate::Outbound, vault_gate::Error>> + Send,
-{
-    let auth_creds = authenticate(props, &mut transport).await?;
-
-    let creds = if integrity::is_signing_available(&props.actors.vault)
+async fn verify_integrity(
+    db: &DatabasePool,
+    vault: &ActorRef<Vault>,
+    credentials: &Credentials,
+) -> Result<(), Error> {
+    let mut conn = db
+        .get()
        .await
-        .unwrap_or(false)
-    {
-        auth_creds.creds
-    } else {
-        run_vault_gate(props, &mut transport, auth_creds).await?
-    };
+        .map_err(|_| Error::Internal("DB unavailable".into()))?;
+    match integrity::verify_entity(&mut conn, &vault, credentials, credentials.id).await {
+        Ok(AttestationStatus::Attested) => Ok(()),
+        Ok(AttestationStatus::Unavailable) => {
+            Err(Error::Internal("Vault sealed during promotion".into()))
+        }
+        Err(e) => {
+            error!(?e, "Integrity verification failed during unseal promotion");
+            Err(Error::Internal("Integrity check failed".into()))
+        }
+    }
+}

-    Ok(UserAgentSession::spawn(UserAgentSession::new(
-        props.clone(),
-        creds,
-        oob_sender,
-    )))
+async fn should_run_gate(vault: &ActorRef<Vault>) -> Result<bool, Error> {
+    let vault_state = vault
+        .ask(GetState {})
+        .await
+        .map_err(|_| Error::Internal("Failed to contact the vault".into()))?;
+
+    Ok(!matches!(
+        vault_state,
+        crate::actors::vault::VaultState::Unsealed
+    ))
 }

 async fn run_vault_gate<T>(
    props: &UserAgentConnection,
    transport: &mut T,
-    auth_creds: AuthCredentials,
-) -> Result<Credentials, Error>
+    auth_creds: Credentials,
+) -> Result<(), Error>
 where
    T: Bi<vault_gate::Inbound, Result<vault_gate::Outbound, vault_gate::Error>> + Send + ?Sized,
 {
@@ -173,3 +158,28 @@ where
    gate.kill();
    result
 }
+
+pub async fn start<T>(
+    props: &mut UserAgentConnection,
+    mut transport: T,
+    oob_sender: Box<dyn Sender<OutOfBand>>,
+) -> Result<ActorRef<UserAgentSession>, Error>
+where
+    T: Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> + Send,
+    T: Bi<vault_gate::Inbound, Result<vault_gate::Outbound, vault_gate::Error>> + Send,
+{
+    let creds = authenticate(props, &mut transport).await?;
+
+    // should run vault gate only if sealed / unbootstrapped
+    if should_run_gate(&props.actors.vault).await? {
+        run_vault_gate(props, &mut transport, creds.clone()).await?;
+    }
+
+    // checking the integrity
+    verify_integrity(&props.db, &props.actors.vault, &creds).await?;
+
+    Ok(UserAgentSession::spawn(UserAgentSession::new(
+        props.clone(),
+        oob_sender,
+    )))
+}
--- a/server/crates/arbiter-server/src/peers/user_agent/session/handlers.rs
+++ b/server/crates/arbiter-server/src/peers/user_agent/session/handlers.rs
@@ -1,37 +1,21 @@
-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};
-use kameo::error::SendError;
-use kameo::messages;
-use kameo::prelude::Context;
-use tracing::{error, info};
-use x25519_dalek::{EphemeralSecret, PublicKey};
-
-use crate::actors::flow_coordinator::client_connect_approval::ClientApprovalAnswer;
-use crate::actors::{
-    evm::{
+use super::{Error, UserAgentSession};
+use crate::{
+    actors::evm::{
        ClientSignTransaction, Generate, ListWallets, SignTransactionError as EvmSignError,
        UseragentCreateGrant, UseragentListGrants,
    },
-    vault::{self, Bootstrap, TryUnseal},
-};
-use crate::db::models::{
-    EvmWalletAccess, NewEvmWalletAccess, ProgramClient, ProgramClientMetadata,
-};
-use crate::evm::policies::{Grant, SpecificGrant};
-use crate::{
+    actors::flow_coordinator::client_connect_approval::ClientApprovalAnswer,
    actors::vault::VaultState,
+    db::models::{EvmWalletAccess, NewEvmWalletAccess, ProgramClient, ProgramClientMetadata},
+    evm::policies::{Grant, SpecificGrant},
 };
+use arbiter_crypto::authn;

-use super::{Error, UserAgentSession};
-
+use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
+use diesel::{ExpressionMethods as _, QueryDsl as _, SelectableHelper};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use kameo::{error::SendError, messages, prelude::Context};
+use tracing::error;

 #[derive(Debug, Error)]
 pub enum SignTransactionError {
--- a/server/crates/arbiter-server/src/peers/user_agent/session/mod.rs
+++ b/server/crates/arbiter-server/src/peers/user_agent/session/mod.rs
@@ -1,23 +1,18 @@
-use arbiter_crypto::authn;
-use diesel::{ExpressionMethods, QueryDsl};
-use diesel_async::{RunQueryDsl};
-use kameo_actors::message_bus::Register;
-
-use std::{borrow::Cow, collections::HashMap};
-
-use arbiter_proto::transport::Sender;
-use kameo::{Actor, actor::ActorRef, messages, prelude::Message};
-use thiserror::Error;
-use tracing::error;
-
+use super::{OutOfBand, UserAgentConnection};
 use crate::{
    actors::{
-        flow_coordinator::{RegisterUserAgent, client_connect_approval::ClientApprovalController},
-        vault::events,
-    }, crypto::integrity, db::schema::useragent_client, peers::{client::ClientProfile, user_agent::{AuthCredentials, Credentials}}
+        flow_coordinator::client_connect_approval::ClientApprovalController,
+        useragent_registry::ConnectUseragent,
+    },
+    peers::client::ClientProfile,
 };
+use arbiter_crypto::authn;
+use arbiter_proto::transport::Sender;

-use super::{OutOfBand, UserAgentConnection};
+use kameo::{Actor, actor::ActorRef, messages};
+use std::{borrow::Cow, collections::HashMap};
+use thiserror::Error;
+use tracing::error;

 #[derive(Debug, Error)]
 pub enum Error {
@@ -55,7 +50,6 @@ pub struct PendingClientApproval {
 }

 pub struct UserAgentSession {
-    creds: Credentials,
    props: UserAgentConnection,
    sender: Box<dyn Sender<OutOfBand>>,

@@ -65,13 +59,8 @@ pub struct UserAgentSession {
 pub mod handlers;

 impl UserAgentSession {
-    pub(crate) fn new(
-        props: UserAgentConnection,
-        creds: Credentials,
-        sender: Box<dyn Sender<OutOfBand>>,
-    ) -> Self {
+    pub(crate) fn new(props: UserAgentConnection, sender: Box<dyn Sender<OutOfBand>>) -> Self {
        Self {
-            creds,
            props,
            sender,
            pending_client_approvals: Default::default(),
@@ -123,17 +112,17 @@ impl Actor for UserAgentSession {
    ) -> Result<Self, Self::Error> {
        args.props
            .actors
-            .flow_coordinator
-            .ask(RegisterUserAgent {
+            .useragent_registry
+            .ask(ConnectUseragent {
                actor: this.clone(),
            })
            .await
            .map_err(|err| {
                error!(
                    ?err,
-                    "Failed to register user agent connection with flow coordinator"
+                    "Failed to register user agent connection with user agent registry"
                );
-                Error::internal("Failed to register user agent connection with flow coordinator")
+                Error::internal("Failed to register user agent connection with user agent registry")
            })?;
        Ok(args)
    }
--- a/server/crates/arbiter-server/src/peers/user_agent/vault_gate/mod.rs
+++ b/server/crates/arbiter-server/src/peers/user_agent/vault_gate/mod.rs
@@ -1,4 +1,15 @@
+use super::Credentials;
+use crate::{
+    actors::{
+        GlobalActors,
+        vault::{self, Bootstrap, GetState, TryUnseal, VaultState, events},
+    },
+    crypto::integrity::{self},
+    db::DatabasePool,
+};
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use state::*;
+
 use chacha20poly1305::{AeadInPlace, KeyInit as _, XChaCha20Poly1305, XNonce};
 use kameo::{Actor, error::SendError, messages, prelude::Message};
 use kameo_actors::message_bus::Register;
@@ -7,17 +18,6 @@ use tracing::{error, info};
 use x25519_dalek::{EphemeralSecret, PublicKey, SharedSecret};

 pub mod state;
-use state::*;
-
-use super::{AuthCredentials, Credentials};
-use crate::{
-    actors::{
-        GlobalActors,
-        vault::{self, Bootstrap, TryUnseal, events},
-    },
-    crypto::integrity::{self, AttestationStatus},
-    db::DatabasePool,
-};

 #[derive(Debug, thiserror::Error)]
 pub enum Error {
@@ -43,8 +43,8 @@ pub struct HandshakeResponse {
 }

 pub struct VaultGate {
-    pub auth_creds: AuthCredentials,
-    pub promotion_tx: Option<oneshot::Sender<Result<Credentials, Error>>>,
+    pub auth_creds: Credentials,
+    pub promotion_tx: Option<oneshot::Sender<Result<(), Error>>>,
    pub state: State,
    pub actors: GlobalActors,
    pub db: DatabasePool,
@@ -52,10 +52,10 @@ pub struct VaultGate {

 impl VaultGate {
    pub fn new(
-        auth_creds: AuthCredentials,
+        auth_creds: Credentials,
        actors: GlobalActors,
        db: DatabasePool,
-        promotion_tx: oneshot::Sender<Result<Credentials, Error>>,
+        promotion_tx: oneshot::Sender<Result<(), Error>>,
    ) -> Self {
        Self {
            auth_creds,
@@ -228,6 +228,18 @@ impl VaultGate {
            }
        }
    }
+
+    #[message]
+    pub async fn handle_vault_state(&mut self) -> Result<VaultState, Error> {
+        let answer = self
+            .actors
+            .vault
+            .ask(GetState {})
+            .await
+            .map_err(|_| Error::internal("failed to query vault"))?;
+
+        Ok(answer)
+    }
 }

 impl Message<events::Bootstrapped> for VaultGate {
@@ -239,14 +251,23 @@ impl Message<events::Bootstrapped> for VaultGate {
        ctx: &mut kameo::prelude::Context<Self, Self::Reply>,
    ) -> Self::Reply {
        let result = async {
-            let mut conn = self.db.get().await.map_err(|_| Error::internal("DB unavailable"))?;
-            integrity::sign_entity(&mut conn, &self.actors.vault, &self.auth_creds, self.auth_creds.creds.id)
+            let mut conn = self
+                .db
+                .get()
                .await
-                .map_err(|e| {
-                    error!(?e, "Failed to sign integrity envelope on bootstrap");
-                    Error::internal("Integrity sign failed")
-                })?;
-            Ok(self.auth_creds.creds.clone())
+                .map_err(|_| Error::internal("DB unavailable"))?;
+            integrity::sign_entity(
+                &mut conn,
+                &self.actors.vault,
+                &self.auth_creds,
+                self.auth_creds.id,
+            )
+            .await
+            .map_err(|e| {
+                error!(?e, "Failed to sign integrity envelope on bootstrap");
+                Error::internal("Integrity sign failed")
+            })?;
+            Ok(())
        }
        .await;

@@ -265,30 +286,8 @@ impl Message<events::Unsealed> for VaultGate {
        _: events::Unsealed,
        ctx: &mut kameo::prelude::Context<Self, Self::Reply>,
    ) -> Self::Reply {
-        let result = async {
-            let mut conn = self.db.get().await.map_err(|_| Error::internal("DB unavailable"))?;
-            match integrity::verify_entity(
-                &mut conn,
-                &self.actors.vault,
-                &self.auth_creds,
-                self.auth_creds.creds.id,
-            )
-            .await
-            {
-                Ok(AttestationStatus::Attested) => Ok(self.auth_creds.creds.clone()),
-                Ok(AttestationStatus::Unavailable) => {
-                    Err(Error::internal("Vault sealed during promotion"))
-                }
-                Err(e) => {
-                    error!(?e, "Integrity verification failed during unseal promotion");
-                    Err(Error::InvalidKey)
-                }
-            }
-        }
-        .await;
-
        if let Some(tx) = self.promotion_tx.take() {
-            let _ = tx.send(result);
+            let _ = tx.send(Ok(()));
        }
        ctx.stop();
    }
--- a/server/crates/arbiter-server/src/peers/user_agent/vault_gate/state.rs
+++ b/server/crates/arbiter-server/src/peers/user_agent/vault_gate/state.rs
@@ -1,10 +1,4 @@
-use std::sync::Mutex;
-
-use x25519_dalek::{EphemeralSecret, PublicKey, SharedSecret};
-
-pub struct Handshake {
-    client_pubkey: PublicKey,
-}
+use x25519_dalek::{PublicKey, SharedSecret};

 #[derive(Default)]
 pub enum State {
--- a/server/crates/arbiter-server/tests/client/auth.rs
+++ b/server/crates/arbiter-server/tests/client/auth.rs
@@ -1,21 +1,23 @@
+use super::common::ChannelTransport;
 use arbiter_crypto::{
-    authn::{self, CLIENT_CONTEXT, format_challenge},
+    authn::{self, AuthChallenge, CLIENT_CONTEXT},
    safecell::{SafeCell, SafeCellHandle as _},
 };
-use arbiter_proto::ClientMetadata;
-use arbiter_proto::transport::{Receiver, Sender};
+use arbiter_proto::{
+    ClientMetadata,
+    transport::{Receiver, Sender},
+};
 use arbiter_server::{
    actors::{GlobalActors, vault::Bootstrap},
    crypto::integrity,
    db::{self, schema},
    peers::client::{ClientConnection, ClientCredentials, auth, connect_client},
 };
+
 use diesel::{ExpressionMethods as _, NullableExpressionMethods as _, QueryDsl as _, insert_into};
 use diesel_async::RunQueryDsl;
 use ml_dsa::{KeyGen, MlDsa87, SigningKey, VerifyingKey, signature::Keypair as _};

-use super::common::ChannelTransport;
-
 fn metadata(name: &str, description: Option<&str>, version: Option<&str>) -> ClientMetadata {
    ClientMetadata {
        name: name.to_owned(),
@@ -58,7 +60,6 @@ async fn insert_registered_client(
        &actors.vault,
        &ClientCredentials {
            pubkey: pubkey.into(),
-            nonce: 1,
        },
        client_id,
    )
@@ -66,12 +67,8 @@ async fn insert_registered_client(
    .unwrap();
 }

-fn sign_client_challenge(
-    key: &SigningKey<MlDsa87>,
-    nonce: i32,
-    pubkey: &authn::PublicKey,
-) -> authn::Signature {
-    let challenge = format_challenge(nonce, &pubkey.to_bytes());
+fn sign_client_challenge(key: &SigningKey<MlDsa87>, challenge: &AuthChallenge) -> authn::Signature {
+    let challenge = challenge.format();
    key.signing_key()
        .sign_deterministic(&challenge, CLIENT_CONTEXT)
        .unwrap()
@@ -86,10 +83,7 @@ async fn insert_bootstrap_sentinel_useragent(db: &db::DatabasePool) {
        .to_vec();

    insert_into(schema::useragent_client::table)
-        .values((
-            schema::useragent_client::public_key.eq(sentinel_key),
-            schema::useragent_client::key_type.eq(1i32),
-        ))
+        .values((schema::useragent_client::public_key.eq(sentinel_key),))
        .execute(&mut conn)
        .await
        .unwrap();
@@ -111,7 +105,7 @@ async fn spawn_test_actors(db: &db::DatabasePool) -> GlobalActors {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_unregistered_pubkey_rejected() {
+async fn test_unregistered_pubkey_rejected() {
    let db = db::create_test_pool().await;

    let (server_transport, mut test_transport) = ChannelTransport::new();
@@ -138,7 +132,7 @@ pub async fn test_unregistered_pubkey_rejected() {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_challenge_auth() {
+async fn test_challenge_auth() {
    let db = db::create_test_pool().await;
    let actors = spawn_test_actors(&db).await;

@@ -175,14 +169,14 @@ pub async fn test_challenge_auth() {
        .expect("should receive challenge");
    let challenge = match response {
        Ok(resp) => match resp {
-            auth::Outbound::AuthChallenge { pubkey, nonce } => (pubkey, nonce),
+            auth::Outbound::AuthChallenge { challenge } => challenge,
            other => panic!("Expected AuthChallenge, got {other:?}"),
        },
        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
    };

    // Sign the challenge and send solution
-    let signature = sign_client_challenge(&new_key, challenge.1, &challenge.0);
+    let signature = sign_client_challenge(&new_key, &challenge);

    test_transport
        .send(auth::Inbound::AuthChallengeSolution { signature })
@@ -205,7 +199,7 @@ pub async fn test_challenge_auth() {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_metadata_unchanged_does_not_append_history() {
+async fn test_metadata_unchanged_does_not_append_history() {
    let db = db::create_test_pool().await;
    let actors = spawn_test_actors(&db).await;
    let new_key = MlDsa87::key_gen(&mut rand::rng());
@@ -230,11 +224,11 @@ pub async fn test_metadata_unchanged_does_not_append_history() {
        .unwrap();

    let response = test_transport.recv().await.unwrap().unwrap();
-    let (pubkey, nonce) = match response {
-        auth::Outbound::AuthChallenge { pubkey, nonce } => (pubkey, nonce),
+    let challenge = match response {
+        auth::Outbound::AuthChallenge { challenge } => challenge,
        other => panic!("Expected AuthChallenge, got {other:?}"),
    };
-    let signature = sign_client_challenge(&new_key, nonce, &pubkey);
+    let signature = sign_client_challenge(&new_key, &challenge);
    test_transport
        .send(auth::Inbound::AuthChallengeSolution { signature })
        .await
@@ -262,7 +256,7 @@ pub async fn test_metadata_unchanged_does_not_append_history() {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_metadata_change_appends_history_and_repoints_binding() {
+async fn test_metadata_change_appends_history_and_repoints_binding() {
    let db = db::create_test_pool().await;
    let actors = spawn_test_actors(&db).await;
    let new_key = MlDsa87::key_gen(&mut rand::rng());
@@ -292,11 +286,11 @@ pub async fn test_metadata_change_appends_history_and_repoints_binding() {
        .unwrap();

    let response = test_transport.recv().await.unwrap().unwrap();
-    let (pubkey, nonce) = match response {
-        auth::Outbound::AuthChallenge { pubkey, nonce } => (pubkey, nonce),
+    let challenge = match response {
+        auth::Outbound::AuthChallenge { challenge } => challenge,
        other => panic!("Expected AuthChallenge, got {other:?}"),
    };
-    let signature = sign_client_challenge(&new_key, nonce, &pubkey);
+    let signature = sign_client_challenge(&new_key, &challenge);
    test_transport
        .send(auth::Inbound::AuthChallengeSolution { signature })
        .await
@@ -349,7 +343,7 @@ 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() {
+async fn test_challenge_auth_rejects_integrity_tag_mismatch() {
    let db = db::create_test_pool().await;
    let actors = spawn_test_actors(&db).await;

--- a/server/crates/arbiter-server/tests/common/mod.rs
+++ b/server/crates/arbiter-server/tests/common/mod.rs
@@ -11,7 +11,7 @@ use diesel_async::RunQueryDsl;
 use tokio::sync::mpsc;

 #[allow(dead_code)]
-pub async fn bootstrapped_vault(db: &db::DatabasePool) -> Vault {
+pub(crate) async fn bootstrapped_vault(db: &db::DatabasePool) -> Vault {
    let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
        .await
        .unwrap();
@@ -23,7 +23,7 @@ pub async fn bootstrapped_vault(db: &db::DatabasePool) -> Vault {
 }

 #[allow(dead_code)]
-pub async fn root_key_history_id(db: &db::DatabasePool) -> i32 {
+pub(crate) async fn root_key_history_id(db: &db::DatabasePool) -> i32 {
    let mut conn = db.get().await.unwrap();
    let id = schema::arbiter_settings::table
        .select(schema::arbiter_settings::root_key_id)
@@ -34,14 +34,14 @@ pub async fn root_key_history_id(db: &db::DatabasePool) -> i32 {
 }

 #[allow(dead_code)]
-pub struct ChannelTransport<T, Y> {
+pub(crate) struct ChannelTransport<T, Y> {
    receiver: mpsc::Receiver<T>,
    sender: mpsc::Sender<Y>,
 }

 impl<T, Y> ChannelTransport<T, Y> {
    #[allow(dead_code)]
-    pub fn new() -> (Self, ChannelTransport<Y, T>) {
+    pub(crate) fn new() -> (Self, ChannelTransport<Y, T>) {
        let (tx1, rx1) = mpsc::channel(10);
        let (tx2, rx2) = mpsc::channel(10);
        (
--- a/server/crates/arbiter-server/tests/user_agent/auth.rs
+++ b/server/crates/arbiter-server/tests/user_agent/auth.rs
@@ -1,36 +1,153 @@
+use super::common::ChannelTransport;
 use arbiter_crypto::{
-    authn::{self, USERAGENT_CONTEXT, format_challenge},
+    authn::{self, AuthChallenge, USERAGENT_CONTEXT},
    safecell::{SafeCell, SafeCellHandle as _},
 };
-
-use arbiter_proto::transport::{Receiver, Sender};
+use arbiter_proto::transport::{Error as TransportError, Receiver, Sender};
 use arbiter_server::{
    actors::{GlobalActors, bootstrap::GetToken, vault::Bootstrap},
    crypto::integrity,
    db::{self, schema},
-    peers::user_agent::{AuthCredentials, Credentials, UserAgentConnection, auth},
+    peers::user_agent::{self, Credentials, UserAgentConnection, auth, vault_gate},
 };
+
+use async_trait::async_trait;
 use diesel::{ExpressionMethods as _, QueryDsl, insert_into};
 use diesel_async::RunQueryDsl;
 use ml_dsa::{KeyGen, MlDsa87, SigningKey, signature::Keypair as _};
-
-use super::common::ChannelTransport;
+use tokio::sync::mpsc;

 fn sign_useragent_challenge(
    key: &SigningKey<MlDsa87>,
-    nonce: i32,
-    pubkey_bytes: &[u8],
+    challenge: &AuthChallenge,
 ) -> authn::Signature {
-    let challenge = format_challenge(nonce, pubkey_bytes);
+    let challenge = challenge.format();
    key.signing_key()
        .sign_deterministic(&challenge, USERAGENT_CONTEXT)
        .unwrap()
        .into()
 }

+fn tamper_challenge(challenge: &AuthChallenge) -> AuthChallenge {
+    let mut challenge = challenge.clone();
+    challenge.nonce[0] ^= 1;
+    challenge
+}
+
+struct NullOobSender;
+
+#[async_trait]
+impl Sender<user_agent::OutOfBand> for NullOobSender {
+    async fn send(&mut self, _item: user_agent::OutOfBand) -> Result<(), TransportError> {
+        Ok(())
+    }
+}
+
+struct StartServerTransport {
+    auth_rx: mpsc::Receiver<auth::Inbound>,
+    auth_tx: mpsc::Sender<Result<auth::Outbound, auth::Error>>,
+    vault_rx: mpsc::Receiver<vault_gate::Inbound>,
+    vault_tx: mpsc::Sender<Result<vault_gate::Outbound, vault_gate::Error>>,
+}
+
+struct StartTestTransport {
+    auth_rx: mpsc::Receiver<Result<auth::Outbound, auth::Error>>,
+    auth_tx: mpsc::Sender<auth::Inbound>,
+}
+
+fn start_transport_pair() -> (StartServerTransport, StartTestTransport) {
+    let (auth_in_tx, auth_in_rx) = mpsc::channel(10);
+    let (auth_out_tx, auth_out_rx) = mpsc::channel(10);
+    let (_vault_in_tx, vault_in_rx) = mpsc::channel(10);
+    let (vault_out_tx, _vault_out_rx) = mpsc::channel(10);
+
+    (
+        StartServerTransport {
+            auth_rx: auth_in_rx,
+            auth_tx: auth_out_tx,
+            vault_rx: vault_in_rx,
+            vault_tx: vault_out_tx,
+        },
+        StartTestTransport {
+            auth_rx: auth_out_rx,
+            auth_tx: auth_in_tx,
+        },
+    )
+}
+
+#[async_trait]
+impl Receiver<auth::Inbound> for StartServerTransport {
+    async fn recv(&mut self) -> Option<auth::Inbound> {
+        self.auth_rx.recv().await
+    }
+}
+
+#[async_trait]
+impl Sender<Result<auth::Outbound, auth::Error>> for StartServerTransport {
+    async fn send(
+        &mut self,
+        item: Result<auth::Outbound, auth::Error>,
+    ) -> Result<(), TransportError> {
+        self.auth_tx
+            .send(item)
+            .await
+            .map_err(|_| TransportError::ChannelClosed)
+    }
+}
+
+impl arbiter_proto::transport::Bi<auth::Inbound, Result<auth::Outbound, auth::Error>>
+    for StartServerTransport
+{
+}
+
+#[async_trait]
+impl Receiver<vault_gate::Inbound> for StartServerTransport {
+    async fn recv(&mut self) -> Option<vault_gate::Inbound> {
+        self.vault_rx.recv().await
+    }
+}
+
+#[async_trait]
+impl Sender<Result<vault_gate::Outbound, vault_gate::Error>> for StartServerTransport {
+    async fn send(
+        &mut self,
+        item: Result<vault_gate::Outbound, vault_gate::Error>,
+    ) -> Result<(), TransportError> {
+        self.vault_tx
+            .send(item)
+            .await
+            .map_err(|_| TransportError::ChannelClosed)
+    }
+}
+
+impl
+    arbiter_proto::transport::Bi<
+        vault_gate::Inbound,
+        Result<vault_gate::Outbound, vault_gate::Error>,
+    > for StartServerTransport
+{
+}
+
+#[async_trait]
+impl Receiver<Result<auth::Outbound, auth::Error>> for StartTestTransport {
+    async fn recv(&mut self) -> Option<Result<auth::Outbound, auth::Error>> {
+        self.auth_rx.recv().await
+    }
+}
+
+#[async_trait]
+impl Sender<auth::Inbound> for StartTestTransport {
+    async fn send(&mut self, item: auth::Inbound) -> Result<(), TransportError> {
+        self.auth_tx
+            .send(item)
+            .await
+            .map_err(|_| TransportError::ChannelClosed)
+    }
+}
+
 #[tokio::test]
 #[test_log::test]
-pub async fn test_bootstrap_token_auth() {
+async fn test_bootstrap_token_auth() {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
    actors
@@ -58,14 +175,29 @@ pub async fn test_bootstrap_token_auth() {
        .await
        .unwrap();

+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(auth::Outbound::AuthChallenge { challenge }) => challenge,
+        other => panic!("Expected AuthChallenge, got {other:?}"),
+    };
+
+    let signature = sign_useragent_challenge(&new_key, &challenge);
+
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution {
+            signature: signature.to_bytes(),
+        })
+        .await
+        .unwrap();
+
    let response = test_transport
        .recv()
        .await
        .expect("should receive auth result");
-    match response {
-        Ok(auth::Outbound::AuthSuccess) => {}
-        other => panic!("Expected AuthSuccess, got {other:?}"),
-    }
+    assert!(matches!(response, Ok(auth::Outbound::AuthSuccess)));

    task.await.unwrap().unwrap();

@@ -80,7 +212,7 @@ pub async fn test_bootstrap_token_auth() {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_bootstrap_invalid_token_auth() {
+async fn test_bootstrap_invalid_token_auth() {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();

@@ -100,6 +232,23 @@ pub async fn test_bootstrap_invalid_token_auth() {
        .await
        .unwrap();

+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(auth::Outbound::AuthChallenge { challenge }) => challenge,
+        other => panic!("Expected AuthChallenge, got {other:?}"),
+    };
+
+    let signature = sign_useragent_challenge(&new_key, &challenge);
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution {
+            signature: signature.to_bytes(),
+        })
+        .await
+        .unwrap();
+
    assert!(matches!(
        task.await.unwrap(),
        Err(auth::Error::InvalidBootstrapToken)
@@ -116,7 +265,7 @@ pub async fn test_bootstrap_invalid_token_auth() {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_challenge_auth() {
+async fn test_challenge_auth() {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
    actors
@@ -133,10 +282,7 @@ pub async fn test_challenge_auth() {
    {
        let mut conn = db.get().await.unwrap();
        let id: i32 = insert_into(schema::useragent_client::table)
-            .values((
-                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
-                schema::useragent_client::key_type.eq(1i32),
-            ))
+            .values((schema::useragent_client::public_key.eq(pubkey_bytes.clone()),))
            .returning(schema::useragent_client::id)
            .get_result(&mut conn)
            .await
@@ -144,12 +290,9 @@ pub async fn test_challenge_auth() {
        integrity::sign_entity(
            &mut conn,
            &actors.vault,
-            &AuthCredentials {
-                creds: Credentials {
-                    id,
-                    pubkey: new_key.verifying_key().into(),
-                },
-                new_nonce: 1,
+            &Credentials {
+                id,
+                pubkey: new_key.verifying_key().into(),
            },
            id,
        )
@@ -178,13 +321,13 @@ pub async fn test_challenge_auth() {
        .expect("should receive challenge");
    let challenge = match response {
        Ok(resp) => match resp {
-            auth::Outbound::AuthChallenge { nonce } => nonce,
+            auth::Outbound::AuthChallenge { challenge } => challenge,
            other => panic!("Expected AuthChallenge, got {other:?}"),
        },
        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
    };

-    let signature = sign_useragent_challenge(&new_key, challenge, &pubkey_bytes);
+    let signature = sign_useragent_challenge(&new_key, &challenge);

    test_transport
        .send(auth::Inbound::AuthChallengeSolution {
@@ -207,7 +350,7 @@ pub async fn test_challenge_auth() {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_challenge_auth_rejects_integrity_tag_mismatch_when_unsealed() {
+async fn test_challenge_auth_rejects_integrity_tag_mismatch_when_unsealed() {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();

@@ -225,20 +368,17 @@ pub async fn test_challenge_auth_rejects_integrity_tag_mismatch_when_unsealed()
    {
        let mut conn = db.get().await.unwrap();
        insert_into(schema::useragent_client::table)
-            .values((
-                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
-                schema::useragent_client::key_type.eq(1i32),
-            ))
+            .values((schema::useragent_client::public_key.eq(pubkey_bytes.clone()),))
            .execute(&mut conn)
            .await
            .unwrap();
    }

-    let (mut server_transport, mut test_transport) = ChannelTransport::new();
+    let (server_transport, mut test_transport) = start_transport_pair();
    let db_for_task = db.clone();
    let task = tokio::spawn(async move {
        let mut props = UserAgentConnection::new(db_for_task, actors);
-        auth::authenticate(&mut props, &mut server_transport).await
+        user_agent::start(&mut props, server_transport, Box::new(NullOobSender)).await
    });

    test_transport
@@ -249,15 +389,42 @@ pub async fn test_challenge_auth_rejects_integrity_tag_mismatch_when_unsealed()
        .await
        .unwrap();

+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(resp) => match resp {
+            auth::Outbound::AuthChallenge { challenge } => challenge,
+            other => panic!("Expected AuthChallenge, got {other:?}"),
+        },
+        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
+    };
+
+    let signature = sign_useragent_challenge(&new_key, &challenge);
+
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution {
+            signature: signature.to_bytes(),
+        })
+        .await
+        .unwrap();
+
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive auth result");
+    assert!(matches!(response, Ok(auth::Outbound::AuthSuccess)));
+
    assert!(matches!(
        task.await.unwrap(),
-        Err(auth::Error::Internal { .. })
+        Err(user_agent::Error::Internal(_))
    ));
 }

 #[tokio::test]
 #[test_log::test]
-pub async fn test_challenge_auth_rejects_invalid_signature() {
+async fn test_challenge_auth_rejects_invalid_signature() {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
    actors
@@ -274,10 +441,7 @@ pub async fn test_challenge_auth_rejects_invalid_signature() {
    {
        let mut conn = db.get().await.unwrap();
        let id: i32 = insert_into(schema::useragent_client::table)
-            .values((
-                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
-                schema::useragent_client::key_type.eq(1i32),
-            ))
+            .values((schema::useragent_client::public_key.eq(pubkey_bytes.clone()),))
            .returning(schema::useragent_client::id)
            .get_result(&mut conn)
            .await
@@ -285,12 +449,9 @@ pub async fn test_challenge_auth_rejects_invalid_signature() {
        integrity::sign_entity(
            &mut conn,
            &actors.vault,
-            &AuthCredentials {
-                creds: Credentials {
-                    id,
-                    pubkey: new_key.verifying_key().into(),
-                },
-                new_nonce: 1,
+            &Credentials {
+                id,
+                pubkey: new_key.verifying_key().into(),
            },
            id,
        )
@@ -319,13 +480,13 @@ pub async fn test_challenge_auth_rejects_invalid_signature() {
        .expect("should receive challenge");
    let challenge = match response {
        Ok(resp) => match resp {
-            auth::Outbound::AuthChallenge { nonce } => nonce,
+            auth::Outbound::AuthChallenge { challenge } => challenge,
            other => panic!("Expected AuthChallenge, got {other:?}"),
        },
        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
    };

-    let signature = sign_useragent_challenge(&new_key, challenge + 1, &pubkey_bytes);
+    let signature = sign_useragent_challenge(&new_key, &tamper_challenge(&challenge));

    test_transport
        .send(auth::Inbound::AuthChallengeSolution {
--- a/server/crates/arbiter-server/tests/user_agent/unseal.rs
+++ b/server/crates/arbiter-server/tests/user_agent/unseal.rs
@@ -9,8 +9,10 @@ use arbiter_server::{
    },
    db,
    peers::user_agent::{
-        AuthCredentials, Credentials,
-        vault_gate::{Error as VaultGateError, HandleHandshake, HandleUnsealEncryptedKey, VaultGate},
+        Credentials,
+        vault_gate::{
+            Error as VaultGateError, HandleHandshake, HandleUnsealEncryptedKey, VaultGate,
+        },
    },
 };

@@ -21,7 +23,11 @@ use x25519_dalek::{EphemeralSecret, PublicKey};

 async fn setup_sealed_gate(
    seal_key: &[u8],
-) -> (db::DatabasePool, kameo::actor::ActorRef<VaultGate>, oneshot::Receiver<Result<Credentials, VaultGateError>>) {
+) -> (
+    db::DatabasePool,
+    kameo::actor::ActorRef<VaultGate>,
+    oneshot::Receiver<Result<(), VaultGateError>>,
+) {
    let db = db::create_test_pool().await;
    let actors = GlobalActors::spawn(db.clone()).await.unwrap();

@@ -36,10 +42,7 @@ async fn setup_sealed_gate(

    let (promotion_tx, promotion_rx) = oneshot::channel();
    let pubkey = authn::SigningKey::generate().public_key();
-    let auth_creds = AuthCredentials {
-        creds: Credentials { id: 1, pubkey },
-        new_nonce: 1,
-    };
+    let auth_creds = Credentials { id: 1, pubkey };
    let gate = VaultGate::spawn(VaultGate::new(auth_creds, actors, db.clone(), promotion_tx));

    (db, gate, promotion_rx)
@@ -79,7 +82,7 @@ async fn client_dh_encrypt(

 #[tokio::test]
 #[test_log::test]
-pub async fn test_unseal_success() {
+async fn test_unseal_success() {
    let seal_key = b"test-seal-key";
    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;

@@ -91,7 +94,7 @@ pub async fn test_unseal_success() {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_unseal_wrong_seal_key() {
+async fn test_unseal_wrong_seal_key() {
    let (_db, gate, _promotion_rx) = setup_sealed_gate(b"correct-key").await;

    let encrypted_key = client_dh_encrypt(&gate, b"wrong-key").await;
@@ -107,7 +110,7 @@ pub async fn test_unseal_wrong_seal_key() {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_unseal_corrupted_ciphertext() {
+async fn test_unseal_corrupted_ciphertext() {
    let (_db, gate, _promotion_rx) = setup_sealed_gate(b"test-key").await;

    let client_secret = EphemeralSecret::random();
@@ -137,7 +140,7 @@ pub async fn test_unseal_corrupted_ciphertext() {

 #[tokio::test]
 #[test_log::test]
-pub async fn test_unseal_retry_after_invalid_key() {
+async fn test_unseal_retry_after_invalid_key() {
    let seal_key = b"real-seal-key";
    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;

--- a/server/crates/arbiter-server/tests/vault/concurrency.rs
+++ b/server/crates/arbiter-server/tests/vault/concurrency.rs
@@ -1,5 +1,4 @@
-use std::collections::{HashMap, HashSet};
-
+use crate::common;
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
    actors::{
@@ -12,10 +11,9 @@ use arbiter_server::{
 use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper, dsl::sql_query};
 use diesel_async::RunQueryDsl;
 use kameo::actor::{ActorRef, Spawn as _};
+use std::collections::{HashMap, HashSet};
 use tokio::task::JoinSet;

-use crate::common;
-
 async fn write_concurrently(
    actor: ActorRef<Vault>,
    prefix: &'static str,
--- a/server/crates/arbiter-server/tests/vault/lifecycle.rs
+++ b/server/crates/arbiter-server/tests/vault/lifecycle.rs
@@ -1,3 +1,4 @@
+use crate::common;
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
    actors::{
@@ -11,8 +12,6 @@ use arbiter_server::{
 use diesel::{QueryDsl, SelectableHelper};
 use diesel_async::RunQueryDsl;

-use crate::common;
-
 #[tokio::test]
 #[test_log::test]
 async fn test_bootstrap() {
@@ -87,7 +86,7 @@ async fn test_new_restores_sealed_state() {
        .await
        .unwrap();
    let err = actor2.decrypt(1).await.unwrap_err();
-    assert!(matches!(err, Error::NotBootstrapped));
+    assert!(matches!(err, Error::Sealed));
 }

 #[tokio::test]
--- a/server/crates/arbiter-server/tests/vault/storage.rs
+++ b/server/crates/arbiter-server/tests/vault/storage.rs
@@ -1,5 +1,4 @@
-use std::collections::HashSet;
-
+use crate::common;
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
    actors::vault::Error,
@@ -9,8 +8,7 @@ use arbiter_server::{

 use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper, dsl::update};
 use diesel_async::RunQueryDsl;
-
-use crate::common;
+use std::collections::HashSet;

 #[tokio::test]
 #[test_log::test]
--- a/useragent/lib/features/connection/auth.dart
+++ b/useragent/lib/features/connection/auth.dart
@@ -7,6 +7,7 @@ import 'package:arbiter/features/identity/pk_manager.dart';
 import 'package:arbiter/proto/arbiter.pbgrpc.dart';
 import 'package:arbiter/proto/user_agent/auth.pb.dart' as ua_auth;
 import 'package:arbiter/proto/user_agent.pb.dart';
+import 'package:arbiter/src/rust/api.dart';
 import 'package:grpc/grpc.dart';
 import 'package:mtcore/markettakers.dart';

@@ -92,7 +93,10 @@ Future<Connection> connectAndAuthorize(
      );
    }

-    final challenge = _formatChallenge(authResponse.challenge, pubkey);
+    final challenge = await formatChallenge(
+      random: authResponse.challenge.random,
+      timestamp: authResponse.challenge.timestampNanos.toInt(),
+    );
    talker.info(
      'Received auth challenge, signing with key ${base64Encode(pubkey)}',
    );
@@ -164,9 +168,3 @@ Future<Connection> _connect(StoredServerInfo serverInfo) async {

  return Connection(channel: channel, tx: tx, rx: rx);
 }
-
-List<int> _formatChallenge(ua_auth.AuthChallenge challenge, List<int> pubkey) {
-  final encodedPubkey = base64Encode(pubkey);
-  final payload = "${challenge.nonce}:$encodedPubkey";
-  return utf8.encode(payload);
-}
--- a/useragent/lib/proto/client/auth.pb.dart
+++ b/useragent/lib/proto/client/auth.pb.dart
@@ -12,6 +12,7 @@

 import 'dart:core' as $core;

+import 'package:fixnum/fixnum.dart' as $fixnum;
 import 'package:protobuf/protobuf.dart' as $pb;

 import '../shared/client.pb.dart' as $0;
@@ -94,12 +95,12 @@ class AuthChallengeRequest extends $pb.GeneratedMessage {

 class AuthChallenge extends $pb.GeneratedMessage {
  factory AuthChallenge({
-    $core.List<$core.int>? pubkey,
-    $core.int? nonce,
+    $fixnum.Int64? timestampNanos,
+    $core.List<$core.int>? random,
  }) {
    final result = create();
-    if (pubkey != null) result.pubkey = pubkey;
-    if (nonce != null) result.nonce = nonce;
+    if (timestampNanos != null) result.timestampNanos = timestampNanos;
+    if (random != null) result.random = random;
    return result;
  }

@@ -117,9 +118,11 @@ class AuthChallenge extends $pb.GeneratedMessage {
      package:
          const $pb.PackageName(_omitMessageNames ? '' : 'arbiter.client.auth'),
      createEmptyInstance: create)
+    ..a<$fixnum.Int64>(
+        1, _omitFieldNames ? '' : 'timestampNanos', $pb.PbFieldType.OU6,
+        defaultOrMaker: $fixnum.Int64.ZERO)
    ..a<$core.List<$core.int>>(
-        1, _omitFieldNames ? '' : 'pubkey', $pb.PbFieldType.OY)
-    ..aI(2, _omitFieldNames ? '' : 'nonce')
+        2, _omitFieldNames ? '' : 'random', $pb.PbFieldType.OY)
    ..hasRequiredFields = false;

  @$core.Deprecated('See https://github.com/google/protobuf.dart/issues/998.')
@@ -142,22 +145,22 @@ class AuthChallenge extends $pb.GeneratedMessage {
  static AuthChallenge? _defaultInstance;

  @$pb.TagNumber(1)
-  $core.List<$core.int> get pubkey => $_getN(0);
+  $fixnum.Int64 get timestampNanos => $_getI64(0);
  @$pb.TagNumber(1)
-  set pubkey($core.List<$core.int> value) => $_setBytes(0, value);
+  set timestampNanos($fixnum.Int64 value) => $_setInt64(0, value);
  @$pb.TagNumber(1)
-  $core.bool hasPubkey() => $_has(0);
+  $core.bool hasTimestampNanos() => $_has(0);
  @$pb.TagNumber(1)
-  void clearPubkey() => $_clearField(1);
+  void clearTimestampNanos() => $_clearField(1);

  @$pb.TagNumber(2)
-  $core.int get nonce => $_getIZ(1);
+  $core.List<$core.int> get random => $_getN(1);
  @$pb.TagNumber(2)
-  set nonce($core.int value) => $_setSignedInt32(1, value);
+  set random($core.List<$core.int> value) => $_setBytes(1, value);
  @$pb.TagNumber(2)
-  $core.bool hasNonce() => $_has(1);
+  $core.bool hasRandom() => $_has(1);
  @$pb.TagNumber(2)
-  void clearNonce() => $_clearField(2);
+  void clearRandom() => $_clearField(2);
 }

 class AuthChallengeSolution extends $pb.GeneratedMessage {
--- a/useragent/lib/proto/client/auth.pbjson.dart
+++ b/useragent/lib/proto/client/auth.pbjson.dart
@@ -62,15 +62,15 @@ final $typed_data.Uint8List authChallengeRequestDescriptor = $convert.base64Deco
 const AuthChallenge$json = {
  '1': 'AuthChallenge',
  '2': [
-    {'1': 'pubkey', '3': 1, '4': 1, '5': 12, '10': 'pubkey'},
-    {'1': 'nonce', '3': 2, '4': 1, '5': 5, '10': 'nonce'},
+    {'1': 'timestamp_nanos', '3': 1, '4': 1, '5': 4, '10': 'timestampNanos'},
+    {'1': 'random', '3': 2, '4': 1, '5': 12, '10': 'random'},
  ],
 };

 /// Descriptor for `AuthChallenge`. Decode as a `google.protobuf.DescriptorProto`.
 final $typed_data.Uint8List authChallengeDescriptor = $convert.base64Decode(
-    'Cg1BdXRoQ2hhbGxlbmdlEhYKBnB1YmtleRgBIAEoDFIGcHVia2V5EhQKBW5vbmNlGAIgASgFUg'
-    'Vub25jZQ==');
+    'Cg1BdXRoQ2hhbGxlbmdlEicKD3RpbWVzdGFtcF9uYW5vcxgBIAEoBFIOdGltZXN0YW1wTmFub3'
+    'MSFgoGcmFuZG9tGAIgASgMUgZyYW5kb20=');

@$core.Deprecated('Use authChallengeSolutionDescriptor instead')
 const AuthChallengeSolution$json = {
--- a/useragent/lib/proto/user_agent/auth.pb.dart
+++ b/useragent/lib/proto/user_agent/auth.pb.dart
@@ -12,6 +12,7 @@

 import 'dart:core' as $core;

+import 'package:fixnum/fixnum.dart' as $fixnum;
 import 'package:protobuf/protobuf.dart' as $pb;

 import 'auth.pbenum.dart';
@@ -90,10 +91,12 @@ class AuthChallengeRequest extends $pb.GeneratedMessage {

 class AuthChallenge extends $pb.GeneratedMessage {
  factory AuthChallenge({
-    $core.int? nonce,
+    $fixnum.Int64? timestampNanos,
+    $core.List<$core.int>? random,
  }) {
    final result = create();
-    if (nonce != null) result.nonce = nonce;
+    if (timestampNanos != null) result.timestampNanos = timestampNanos;
+    if (random != null) result.random = random;
    return result;
  }

@@ -111,7 +114,11 @@ class AuthChallenge extends $pb.GeneratedMessage {
      package: const $pb.PackageName(
          _omitMessageNames ? '' : 'arbiter.user_agent.auth'),
      createEmptyInstance: create)
-    ..aI(1, _omitFieldNames ? '' : 'nonce')
+    ..a<$fixnum.Int64>(
+        1, _omitFieldNames ? '' : 'timestampNanos', $pb.PbFieldType.OU6,
+        defaultOrMaker: $fixnum.Int64.ZERO)
+    ..a<$core.List<$core.int>>(
+        2, _omitFieldNames ? '' : 'random', $pb.PbFieldType.OY)
    ..hasRequiredFields = false;

  @$core.Deprecated('See https://github.com/google/protobuf.dart/issues/998.')
@@ -134,13 +141,22 @@ class AuthChallenge extends $pb.GeneratedMessage {
  static AuthChallenge? _defaultInstance;

  @$pb.TagNumber(1)
-  $core.int get nonce => $_getIZ(0);
+  $fixnum.Int64 get timestampNanos => $_getI64(0);
  @$pb.TagNumber(1)
-  set nonce($core.int value) => $_setSignedInt32(0, value);
+  set timestampNanos($fixnum.Int64 value) => $_setInt64(0, value);
  @$pb.TagNumber(1)
-  $core.bool hasNonce() => $_has(0);
+  $core.bool hasTimestampNanos() => $_has(0);
  @$pb.TagNumber(1)
-  void clearNonce() => $_clearField(1);
+  void clearTimestampNanos() => $_clearField(1);
+
+  @$pb.TagNumber(2)
+  $core.List<$core.int> get random => $_getN(1);
+  @$pb.TagNumber(2)
+  set random($core.List<$core.int> value) => $_setBytes(1, value);
+  @$pb.TagNumber(2)
+  $core.bool hasRandom() => $_has(1);
+  @$pb.TagNumber(2)
+  void clearRandom() => $_clearField(2);
 }

 class AuthChallengeSolution extends $pb.GeneratedMessage {
--- a/useragent/lib/proto/user_agent/auth.pbjson.dart
+++ b/useragent/lib/proto/user_agent/auth.pbjson.dart
@@ -67,13 +67,15 @@ final $typed_data.Uint8List authChallengeRequestDescriptor = $convert.base64Deco
 const AuthChallenge$json = {
  '1': 'AuthChallenge',
  '2': [
-    {'1': 'nonce', '3': 1, '4': 1, '5': 5, '10': 'nonce'},
+    {'1': 'timestamp_nanos', '3': 1, '4': 1, '5': 4, '10': 'timestampNanos'},
+    {'1': 'random', '3': 2, '4': 1, '5': 12, '10': 'random'},
  ],
 };

 /// Descriptor for `AuthChallenge`. Decode as a `google.protobuf.DescriptorProto`.
-final $typed_data.Uint8List authChallengeDescriptor = $convert
-    .base64Decode('Cg1BdXRoQ2hhbGxlbmdlEhQKBW5vbmNlGAEgASgFUgVub25jZQ==');
+final $typed_data.Uint8List authChallengeDescriptor = $convert.base64Decode(
+    'Cg1BdXRoQ2hhbGxlbmdlEicKD3RpbWVzdGFtcF9uYW5vcxgBIAEoBFIOdGltZXN0YW1wTmFub3'
+    'MSFgoGcmFuZG9tGAIgASgMUgZyYW5kb20=');

@$core.Deprecated('Use authChallengeSolutionDescriptor instead')
 const AuthChallengeSolution$json = {
--- a/useragent/lib/src/rust/api.dart
+++ b/useragent/lib/src/rust/api.dart
@@ -6,6 +6,14 @@
 import 'frb_generated.dart';
 import 'package:flutter_rust_bridge/flutter_rust_bridge_for_generated.dart';

+Future<Uint8List> formatChallenge({
+  required List<int> random,
+  required PlatformInt64 timestamp,
+}) => RustLib.instance.api.crateApiFormatChallenge(
+  random: random,
+  timestamp: timestamp,
+);
+
 // Rust type: RustOpaqueMoi<flutter_rust_bridge::for_generated::RustAutoOpaqueInner<MldsaKey>>
 abstract class MldsaKey implements RustOpaqueInterface {
  static Future<MldsaKey> fromBytes({required List<int> bytes}) =>
--- a/useragent/lib/src/rust/frb_generated.dart
+++ b/useragent/lib/src/rust/frb_generated.dart
@@ -64,7 +64,7 @@ class RustLib extends BaseEntrypoint<RustLibApi, RustLibApiImpl, RustLibWire> {
  String get codegenVersion => '2.12.0';

  @override
-  int get rustContentHash => -437661335;
+  int get rustContentHash => 1247923898;

  static const kDefaultExternalLibraryLoaderConfig =
      ExternalLibraryLoaderConfig(
@@ -89,6 +89,11 @@ abstract class RustLibApi extends BaseApi {

  Future<Uint8List> crateApiMldsaKeyToBytes({required MldsaKey that});

+  Future<Uint8List> crateApiFormatChallenge({
+    required List<int> random,
+    required PlatformInt64 timestamp,
+  });
+
  RustArcIncrementStrongCountFnType
  get rust_arc_increment_strong_count_MldsaKey;

@@ -267,6 +272,40 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
  TaskConstMeta get kCrateApiMldsaKeyToBytesConstMeta =>
      const TaskConstMeta(debugName: "MldsaKey_to_bytes", argNames: ["that"]);

+  @override
+  Future<Uint8List> crateApiFormatChallenge({
+    required List<int> random,
+    required PlatformInt64 timestamp,
+  }) {
+    return handler.executeNormal(
+      NormalTask(
+        callFfi: (port_) {
+          final serializer = SseSerializer(generalizedFrbRustBinding);
+          sse_encode_list_prim_u_8_loose(random, serializer);
+          sse_encode_i_64(timestamp, serializer);
+          pdeCallFfi(
+            generalizedFrbRustBinding,
+            serializer,
+            funcId: 6,
+            port: port_,
+          );
+        },
+        codec: SseCodec(
+          decodeSuccessData: sse_decode_list_prim_u_8_strict,
+          decodeErrorData: sse_decode_String,
+        ),
+        constMeta: kCrateApiFormatChallengeConstMeta,
+        argValues: [random, timestamp],
+        apiImpl: this,
+      ),
+    );
+  }
+
+  TaskConstMeta get kCrateApiFormatChallengeConstMeta => const TaskConstMeta(
+    debugName: "format_challenge",
+    argNames: ["random", "timestamp"],
+  );
+
  RustArcIncrementStrongCountFnType
  get rust_arc_increment_strong_count_MldsaKey => wire
      .rust_arc_increment_strong_count_RustOpaque_flutter_rust_bridgefor_generatedRustAutoOpaqueInnerMldsaKey;
@@ -314,6 +353,12 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
    return raw as String;
  }

+  @protected
+  PlatformInt64 dco_decode_i_64(dynamic raw) {
+    // Codec=Dco (DartCObject based), see doc to use other codecs
+    return dcoDecodeI64(raw);
+  }
+
  @protected
  List<int> dco_decode_list_prim_u_8_loose(dynamic raw) {
    // Codec=Dco (DartCObject based), see doc to use other codecs
@@ -394,6 +439,12 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
    return utf8.decoder.convert(inner);
  }

+  @protected
+  PlatformInt64 sse_decode_i_64(SseDeserializer deserializer) {
+    // Codec=Sse (Serialization based), see doc to use other codecs
+    return deserializer.buffer.getPlatformInt64();
+  }
+
  @protected
  List<int> sse_decode_list_prim_u_8_loose(SseDeserializer deserializer) {
    // Codec=Sse (Serialization based), see doc to use other codecs
@@ -491,6 +542,12 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
    sse_encode_list_prim_u_8_strict(utf8.encoder.convert(self), serializer);
  }

+  @protected
+  void sse_encode_i_64(PlatformInt64 self, SseSerializer serializer) {
+    // Codec=Sse (Serialization based), see doc to use other codecs
+    serializer.buffer.putPlatformInt64(self);
+  }
+
  @protected
  void sse_encode_list_prim_u_8_loose(
    List<int> self,
--- a/useragent/lib/src/rust/frb_generated.io.dart
+++ b/useragent/lib/src/rust/frb_generated.io.dart
@@ -46,6 +46,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
  @protected
  String dco_decode_String(dynamic raw);

+  @protected
+  PlatformInt64 dco_decode_i_64(dynamic raw);
+
  @protected
  List<int> dco_decode_list_prim_u_8_loose(dynamic raw);

@@ -85,6 +88,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
  @protected
  String sse_decode_String(SseDeserializer deserializer);

+  @protected
+  PlatformInt64 sse_decode_i_64(SseDeserializer deserializer);
+
  @protected
  List<int> sse_decode_list_prim_u_8_loose(SseDeserializer deserializer);

@@ -136,6 +142,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
  @protected
  void sse_encode_String(String self, SseSerializer serializer);

+  @protected
+  void sse_encode_i_64(PlatformInt64 self, SseSerializer serializer);
+
  @protected
  void sse_encode_list_prim_u_8_loose(List<int> self, SseSerializer serializer);

--- a/useragent/lib/src/rust/frb_generated.web.dart
+++ b/useragent/lib/src/rust/frb_generated.web.dart
@@ -48,6 +48,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
  @protected
  String dco_decode_String(dynamic raw);

+  @protected
+  PlatformInt64 dco_decode_i_64(dynamic raw);
+
  @protected
  List<int> dco_decode_list_prim_u_8_loose(dynamic raw);

@@ -87,6 +90,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
  @protected
  String sse_decode_String(SseDeserializer deserializer);

+  @protected
+  PlatformInt64 sse_decode_i_64(SseDeserializer deserializer);
+
  @protected
  List<int> sse_decode_list_prim_u_8_loose(SseDeserializer deserializer);

@@ -138,6 +144,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
  @protected
  void sse_encode_String(String self, SseSerializer serializer);

+  @protected
+  void sse_encode_i_64(PlatformInt64 self, SseSerializer serializer);
+
  @protected
  void sse_encode_list_prim_u_8_loose(List<int> self, SseSerializer serializer);

--- a/useragent/mise.toml
+++ b/useragent/mise.toml
@@ -0,0 +1,4 @@
+[tasks.codegen]
+run = '''
+  flutter_rust_bridge_codegen generate 
+'''
--- a/useragent/rust/Cargo.lock
+++ b/useragent/rust/Cargo.lock
@@ -232,10 +232,11 @@ checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
 name = "arbiter-crypto"
 version = "0.1.0"
 dependencies = [
- "base64",
+ "chrono",
 "memsafe",
 "ml-dsa",
 "rand",
+ "x-wing",
 ]

 [[package]]
@@ -486,12 +487,6 @@ dependencies = [
 "rustc-demangle",
 ]

-[[package]]
-name = "base64"
-version = "0.22.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
-
 [[package]]
 name = "base64ct"
 version = "1.8.3"
@@ -713,10 +708,24 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6f8d983286843e49675a4b7a2d174efe136dc93a18d69130dd18198a6c167601"
 dependencies = [
 "cfg-if",
- "cpufeatures",
+ "cpufeatures 0.3.0",
 "rand_core",
 ]

+[[package]]
+name = "chrono"
+version = "0.4.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c673075a2e0e5f4a1dde27ce9dee1ea4558c7ffe648f576438a20ca1d2acc4b0"
+dependencies = [
+ "iana-time-zone",
+ "js-sys",
+ "num-traits",
+ "serde",
+ "wasm-bindgen",
+ "windows-link",
+]
+
 [[package]]
 name = "clipboard-win"
 version = "5.4.1"
@@ -837,6 +846,15 @@ dependencies = [
 "libc",
 ]

+[[package]]
+name = "cpufeatures"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59ed5838eebb26a2bb2e58f6d5b5316989ae9d08bab10e0e6d103e656d1b0280"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "cpufeatures"
 version = "0.3.0"
@@ -884,6 +902,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "77727bb15fa921304124b128af125e7e3b968275d1b108b379190264f4423710"
 dependencies = [
 "hybrid-array",
+ "rand_core",
 ]

 [[package]]
@@ -901,6 +920,32 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f27ae1dd37df86211c42e150270f82743308803d90a6f6e6651cd730d5e1732f"

+[[package]]
+name = "curve25519-dalek"
+version = "5.0.0-pre.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "335f1947f241137a14106b6f5acc5918a5ede29c9d71d3f2cb1678d5075d9fc3"
+dependencies = [
+ "cfg-if",
+ "cpufeatures 0.2.17",
+ "curve25519-dalek-derive",
+ "fiat-crypto",
+ "rustc_version",
+ "subtle",
+ "zeroize",
+]
+
+[[package]]
+name = "curve25519-dalek-derive"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f46882e17999c6cc590af592290432be3bce0428cb0d5f8b6715e4dc7b383eb3"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "dart-sys"
 version = "4.1.5"
@@ -1314,6 +1359,12 @@ dependencies = [
 "bytemuck",
 ]

+[[package]]
+name = "fiat-crypto"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "64cd1e32ddd350061ae6edb1b082d7c54915b5c672c389143b9a63403a109f24"
+
 [[package]]
 name = "flate2"
 version = "1.1.9"
@@ -1773,10 +1824,35 @@ version = "0.4.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3944cf8cf766b40e2a1a333ee5e9b563f854d5fa49d6a8ca2764e97c6eddb214"
 dependencies = [
+ "ctutils",
 "typenum",
 "zeroize",
 ]

+[[package]]
+name = "iana-time-zone"
+version = "0.1.65"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e31bc9ad994ba00e440a8aa5c9ef0ec67d5cb5e5cb0cc7f8b744a35b389cc470"
+dependencies = [
+ "android_system_properties",
+ "core-foundation-sys",
+ "iana-time-zone-haiku",
+ "js-sys",
+ "log",
+ "wasm-bindgen",
+ "windows-core",
+]
+
+[[package]]
+name = "iana-time-zone-haiku"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f31827a206f56af32e590ba56d5d2d085f558508192593743f16b2306495269f"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "icu_collections"
 version = "2.2.0"
@@ -2005,7 +2081,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9e24a010dd405bd7ed803e5253182815b41bf2e6a80cc3bfc066658e03a198aa"
 dependencies = [
 "cfg-if",
- "cpufeatures",
+ "cpufeatures 0.3.0",
+]
+
+[[package]]
+name = "kem"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "01737161ba802849cfd486b5bd209d38ba4943494c249a8126005170c7621edd"
+dependencies = [
+ "crypto-common 0.2.1",
+ "rand_core",
 ]

 [[package]]
@@ -2207,12 +2293,27 @@ dependencies = [
 "zeroize",
 ]

+[[package]]
+name = "ml-kem"
+version = "0.3.0-rc.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "04437cb1a66c0b78740927b76cc61f218344b9f6ef3dd430e283274a718ef0e9"
+dependencies = [
+ "hybrid-array",
+ "kem",
+ "module-lattice",
+ "rand_core",
+ "sha3",
+ "zeroize",
+]
+
 [[package]]
 name = "module-lattice"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "164eb3faeaecbd14b0b2a917c1b4d0c035097a9c559b0bed85c2cdd032bc8faa"
 dependencies = [
+ "ctutils",
 "hybrid-array",
 "num-traits",
 "zeroize",
@@ -3488,6 +3589,12 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6637bab7722d379c8b41ba849228d680cc12d0a45ba1fa2b48f2a30577a06731"

+[[package]]
+name = "subtle"
+version = "2.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292"
+
 [[package]]
 name = "syn"
 version = "2.0.117"
@@ -4761,6 +4868,20 @@ version = "0.6.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1ffae5123b2d3fc086436f8834ae3ab053a283cfac8fe0a0b8eaae044768a4c4"

+[[package]]
+name = "x-wing"
+version = "0.1.0-rc.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e17d0d5f4d1f26b9b9e7477af1d3bef960e1d1fb64edab7912fde472a8a8432e"
+dependencies = [
+ "kem",
+ "ml-kem",
+ "rand_core",
+ "sha3",
+ "x25519-dalek",
+ "zeroize",
+]
+
 [[package]]
 name = "x11-dl"
 version = "2.21.0"
@@ -4793,6 +4914,17 @@ version = "0.13.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ea6fc2961e4ef194dcbfe56bb845534d0dc8098940c7e5c012a258bfec6701bd"

+[[package]]
+name = "x25519-dalek"
+version = "3.0.0-pre.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b3d5d6ff67acd3945b933e592bfa7143db4fcbb2f871754b6b9fbd7847fc5aea"
+dependencies = [
+ "curve25519-dalek",
+ "rand_core",
+ "zeroize",
+]
+
 [[package]]
 name = "xcursor"
 version = "0.3.10"
--- a/useragent/rust/src/api/mod.rs
+++ b/useragent/rust/src/api/mod.rs
@@ -1,13 +1,15 @@
 use anyhow::anyhow;
+use arbiter_crypto::authn::{self, AuthChallenge, USERAGENT_CONTEXT};
 use flutter_rust_bridge::frb;
-use arbiter_crypto::authn::{self, USERAGENT_CONTEXT};

 #[frb(opaque)]
 pub struct MldsaKey(authn::SigningKey);

 impl MldsaKey {
    pub fn from_bytes(bytes: &[u8]) -> anyhow::Result<Self> {
-        let bytes: [u8; 32] = bytes.try_into().map_err(|_| anyhow!("Invalid key length"))?;
+        let bytes: [u8; 32] = bytes
+            .try_into()
+            .map_err(|_| anyhow!("Invalid key length"))?;
        Ok(Self(authn::SigningKey::from_seed(bytes)))
    }

@@ -26,4 +28,11 @@ impl MldsaKey {
    pub fn get_public_key(&self) -> Vec<u8> {
        self.0.public_key().to_bytes().to_vec()
    }
-}
+}
+
+pub fn format_challenge(random: Vec<u8>, timestamp: i64) -> Result<Vec<u8>, String> {
+    let challenge = AuthChallenge::from_parts(&random, timestamp)
+        .map_err(|_| "Invalid nonce length".to_string())?;
+
+    Ok(challenge.format())
+}
--- a/useragent/rust/src/frb_generated.rs
+++ b/useragent/rust/src/frb_generated.rs
@@ -39,7 +39,7 @@ flutter_rust_bridge::frb_generated_boilerplate!(
    default_rust_auto_opaque = RustAutoOpaqueMoi,
 );
 pub(crate) const FLUTTER_RUST_BRIDGE_CODEGEN_VERSION: &str = "2.12.0";
-pub(crate) const FLUTTER_RUST_BRIDGE_CODEGEN_CONTENT_HASH: i32 = -437661335;
+pub(crate) const FLUTTER_RUST_BRIDGE_CODEGEN_CONTENT_HASH: i32 = 1247923898;

 // Section: executor

@@ -267,6 +267,40 @@ fn wire__crate__api__MldsaKey_to_bytes_impl(
        },
    )
 }
+fn wire__crate__api__format_challenge_impl(
+    port_: flutter_rust_bridge::for_generated::MessagePort,
+    ptr_: flutter_rust_bridge::for_generated::PlatformGeneralizedUint8ListPtr,
+    rust_vec_len_: i32,
+    data_len_: i32,
+) {
+    FLUTTER_RUST_BRIDGE_HANDLER.wrap_normal::<flutter_rust_bridge::for_generated::SseCodec, _, _>(
+        flutter_rust_bridge::for_generated::TaskInfo {
+            debug_name: "format_challenge",
+            port: Some(port_),
+            mode: flutter_rust_bridge::for_generated::FfiCallMode::Normal,
+        },
+        move || {
+            let message = unsafe {
+                flutter_rust_bridge::for_generated::Dart2RustMessageSse::from_wire(
+                    ptr_,
+                    rust_vec_len_,
+                    data_len_,
+                )
+            };
+            let mut deserializer =
+                flutter_rust_bridge::for_generated::SseDeserializer::new(message);
+            let api_random = <Vec<u8>>::sse_decode(&mut deserializer);
+            let api_timestamp = <i64>::sse_decode(&mut deserializer);
+            deserializer.end();
+            move |context| {
+                transform_result_sse::<_, String>((move || {
+                    let output_ok = crate::api::format_challenge(api_random, api_timestamp)?;
+                    Ok(output_ok)
+                })())
+            }
+        },
+    )
+}

 // Section: related_funcs

@@ -312,6 +346,13 @@ impl SseDecode for String {
    }
 }

+impl SseDecode for i64 {
+    // Codec=Sse (Serialization based), see doc to use other codecs
+    fn sse_decode(deserializer: &mut flutter_rust_bridge::for_generated::SseDeserializer) -> Self {
+        deserializer.cursor.read_i64::<NativeEndian>().unwrap()
+    }
+}
+
 impl SseDecode for Vec<u8> {
    // Codec=Sse (Serialization based), see doc to use other codecs
    fn sse_decode(deserializer: &mut flutter_rust_bridge::for_generated::SseDeserializer) -> Self {
@@ -371,6 +412,7 @@ fn pde_ffi_dispatcher_primary_impl(
        3 => wire__crate__api__MldsaKey_get_public_key_impl(port, ptr, rust_vec_len, data_len),
        4 => wire__crate__api__MldsaKey_sign_impl(port, ptr, rust_vec_len, data_len),
        5 => wire__crate__api__MldsaKey_to_bytes_impl(port, ptr, rust_vec_len, data_len),
+        6 => wire__crate__api__format_challenge_impl(port, ptr, rust_vec_len, data_len),
        _ => unreachable!(),
    }
 }
@@ -436,6 +478,13 @@ impl SseEncode for String {
    }
 }

+impl SseEncode for i64 {
+    // Codec=Sse (Serialization based), see doc to use other codecs
+    fn sse_encode(self, serializer: &mut flutter_rust_bridge::for_generated::SseSerializer) {
+        serializer.cursor.write_i64::<NativeEndian>(self).unwrap();
+    }
+}
+
 impl SseEncode for Vec<u8> {
    // Codec=Sse (Serialization based), see doc to use other codecs
    fn sse_encode(self, serializer: &mut flutter_rust_bridge::for_generated::SseSerializer) {
Author	SHA1	Message	Date
Skipper	929d50b589	housekeeping(server): clean too-broad visibility markers and organize imports Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-test Pipeline failed Details ci/woodpecker/pr/useragent-analyze Pipeline failed Details	2026-04-18 13:30:09 +02:00
Skipper	70acfc99b5	merge: refactor-integrity-check into main	2026-04-18 13:19:13 +02:00
Skipper	4a8e51ef32	docs: updated to new auth challenge format and removed stale TOCTOU race condition note Some checks failed ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/server-audit Pipeline failed Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-test Pipeline was successful Details ci/woodpecker/pr/useragent-analyze Pipeline failed Details	2026-04-17 18:25:55 +02:00
Skipper	9ee86afc19	fix(useragent): now using new challenge format	2026-04-17 18:19:51 +02:00
Skipper	790026e93b	fix(server::tests): api surface of auth challenge changed	2026-04-17 17:58:22 +02:00
Skipper	0e09afda5d	refactor(server::{useragent::auth, client::auth}): use random based + timestamp nonce instead of monotonic counter in database	2026-04-17 17:44:42 +02:00
Skipper	51e6571d80	refactor(server): now keeps track of useragents, instead of	2026-04-17 00:00:43 +02:00
Skipper	3b828d5874	refactor(server::grpc::vault_gate): standard approach using / traits	2026-04-16 22:15:18 +02:00
Skipper	a6f94e3115	fix(server): sending fixed vault state when on stage	2026-04-16 19:36:41 +02:00
hdbg	f49e995c2f	WIP: `kameo::messages` wiring for transport generalization Some checks failed ci/woodpecker/pr/server-test Pipeline failed Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-audit Pipeline failed Details ci/woodpecker/pr/server-lint Pipeline failed Details ci/woodpecker/pr/useragent-analyze Pipeline failed Details	2026-04-16 17:18:46 +02:00
Stas	62dff3f810	Merge pull request 'refactor(hashing): introduce Hashable derive macro and migrate server types' (#82 ) from hashing-proc-macro into main Some checks failed ci/woodpecker/push/server-audit Pipeline was successful Details ci/woodpecker/push/server-lint Pipeline was successful Details ci/woodpecker/push/server-vet Pipeline failed Details ci/woodpecker/push/server-test Pipeline was successful Details Reviewed-on: #82 Reviewed-by: Stas <business@jexter.tech>	2026-04-08 00:18:40 +00:00
CleverWild	6e22f368c9	refactor(hashing): introduce Hashable derive macro and migrate server types Some checks failed ci/woodpecker/pr/server-audit Pipeline was successful Details ci/woodpecker/pr/server-vet Pipeline failed Details ci/woodpecker/pr/server-lint Pipeline was successful Details ci/woodpecker/pr/server-test Pipeline was successful Details	2026-04-08 01:32:59 +02:00