refactor(server): rework envelopes and integrity check

server/crates/arbiter-server/src/actors/evm/mod.rs

@@ -8,19 +8,18 @@ use rand::{SeedableRng, rng, rngs::StdRng};
 
 use crate::{
     actors::keyholder::{CreateNew, Decrypt, GetState, KeyHolder, KeyHolderState},
+    crypto::integrity,
     db::{
         DatabaseError, DatabasePool,
         models::{self, SqliteTimestamp},
         schema,
     },
     evm::{
-        self, RunKind,
-        policies::{
-            FullGrant, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning,
+        self, ListError, RunKind, policies::{
+            CombinedSettings, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning,
             ether_transfer::EtherTransfer, token_transfers::TokenTransfer,
-        },
+        }
     },
-    integrity,
     safe_cell::{SafeCell, SafeCellHandle as _},
 };
 
@@ -58,8 +57,8 @@ pub enum Error {
     #[error("Database error: {0}")]
     Database(#[from] DatabaseError),
 
-    #[error("Vault is sealed")]
-    VaultSealed,
+    #[error("Integrity violation: {0}")]
+    Integrity(#[from] integrity::Error),
 }
 
 #[derive(Actor)]
@@ -83,20 +82,6 @@ impl EvmActor {
             engine,
         }
     }
-
-    async fn ensure_unsealed(&self) -> Result<(), Error> {
-        let state = self
-            .keyholder
-            .ask(GetState)
-            .await
-            .map_err(|_| Error::KeyholderSend)?;
-
-        if state != KeyHolderState::Unsealed {
-            return Err(Error::VaultSealed);
-        }
-
-        Ok(())
-    }
 }
 
 #[messages]
@@ -151,62 +136,58 @@ impl EvmActor {
         basic: SharedGrantSettings,
         grant: SpecificGrant,
     ) -> Result<i32, Error> {
-        self.ensure_unsealed().await?;
-
         match grant {
-            SpecificGrant::EtherTransfer(settings) => {
-                self.engine
-                    .create_grant::<EtherTransfer>(FullGrant {
-                        basic,
-                        specific: settings,
-                    })
-                    .await
-                    .map_err(Error::from)
-            }
-            SpecificGrant::TokenTransfer(settings) => {
-                self.engine
-                    .create_grant::<TokenTransfer>(FullGrant {
-                        basic,
-                        specific: settings,
-                    })
-                    .await
-                    .map_err(Error::from)
-            }
+            SpecificGrant::EtherTransfer(settings) => self
+                .engine
+                .create_grant::<EtherTransfer>(CombinedSettings {
+                    shared: basic,
+                    specific: settings,
+                })
+                .await
+                .map_err(Error::from),
+            SpecificGrant::TokenTransfer(settings) => self
+                .engine
+                .create_grant::<TokenTransfer>(CombinedSettings {
+                    shared: basic,
+                    specific: settings,
+                })
+                .await
+                .map_err(Error::from),
         }
     }
 
     #[message]
     pub async fn useragent_delete_grant(&mut self, grant_id: i32) -> Result<(), Error> {
-        self.ensure_unsealed().await?;
+        // let mut conn = self.db.get().await.map_err(DatabaseError::from)?;
+        // let keyholder = self.keyholder.clone();
 
-        let mut conn = self.db.get().await.map_err(DatabaseError::from)?;
-        let keyholder = self.keyholder.clone();
+        // diesel_async::AsyncConnection::transaction(&mut conn, |conn| {
+        //     Box::pin(async move {
+        //         diesel::update(schema::evm_basic_grant::table)
+        //             .filter(schema::evm_basic_grant::id.eq(grant_id))
+        //             .set(schema::evm_basic_grant::revoked_at.eq(SqliteTimestamp::now()))
+        //             .execute(conn)
+        //             .await?;
 
-        diesel_async::AsyncConnection::transaction(&mut conn, |conn| {
-            Box::pin(async move {
-                diesel::update(schema::evm_basic_grant::table)
-                    .filter(schema::evm_basic_grant::id.eq(grant_id))
-                    .set(schema::evm_basic_grant::revoked_at.eq(SqliteTimestamp::now()))
-                    .execute(conn)
-                    .await?;
+        //         let signed = integrity::evm::load_signed_grant_by_basic_id(conn, grant_id).await?;
 
-                let signed = integrity::evm::load_signed_grant_by_basic_id(conn, grant_id).await?;
-                integrity::sign_entity(conn, &keyholder, &signed)
-                    .await
-                    .map_err(|_| diesel::result::Error::RollbackTransaction)?;
+        //         diesel::result::QueryResult::Ok(())
+        //     })
+        // })
+        // .await
+        // .map_err(DatabaseError::from)?;
 
-                diesel::result::QueryResult::Ok(())
-            })
-        })
-        .await
-        .map_err(DatabaseError::from)?;
-
-        Ok(())
+        // Ok(())
+        todo!()
     }
 
     #[message]
     pub async fn useragent_list_grants(&mut self) -> Result<Vec<Grant<SpecificGrant>>, Error> {
-        Ok(self.engine.list_all_grants().await?)
+        match self.engine.list_all_grants().await {
+            Ok(grants) => Ok(grants),
+            Err(ListError::Database(db_err)) => Err(Error::Database(db_err)),
+            Err(ListError::Integrity(integrity_err)) => Err(Error::Integrity(integrity_err)),
+        }
     }
 
     #[message]

server/crates/arbiter-server/src/actors/keyholder/mod.rs

@@ -4,9 +4,8 @@ use diesel::{
     dsl::{insert_into, update},
 };
 use diesel_async::{AsyncConnection, RunQueryDsl};
-use hmac::{Hmac, Mac as _};
+use hmac::Mac as _;
 use kameo::{Actor, Reply, messages};
-use sha2::Sha256;
 use strum::{EnumDiscriminants, IntoDiscriminant};
 use tracing::{error, info};
 
@@ -14,7 +13,7 @@ use crate::{
     crypto::{
         KeyCell, derive_key,
         encryption::v1::{self, Nonce},
-        integrity::v1::compute_integrity_tag,
+        integrity::v1::HmacSha256,
     },
     safe_cell::SafeCell,
 };
@@ -26,13 +25,6 @@ use crate::{
     },
     safe_cell::SafeCellHandle as _,
 };
-use encryption::v1::{self, KeyCell, Nonce};
-
-type HmacSha256 = Hmac<Sha256>;
-
-const INTEGRITY_SUBKEY_TAG: &[u8] = b"arbiter/db-integrity-key/v1";
-
-pub mod encryption;
 
 #[derive(Default, EnumDiscriminants)]
 #[strum_discriminants(derive(Reply), vis(pub), name(KeyHolderState))]
@@ -142,19 +134,6 @@ impl KeyHolder {
         Ok(nonce)
     }
 
-    fn derive_integrity_key(root_key: &mut KeyCell) -> [u8; 32] {
-        root_key.0.read_inline(|root_key_bytes| {
-            let mut hmac = match HmacSha256::new_from_slice(root_key_bytes.as_slice()) {
-                Ok(v) => v,
-                Err(_) => unreachable!("HMAC accepts keys of any size"),
-            };
-            hmac.update(INTEGRITY_SUBKEY_TAG);
-            let mut out = [0u8; 32];
-            out.copy_from_slice(&hmac.finalize().into_bytes());
-            out
-        })
-    }
-
     #[message]
     pub async fn bootstrap(&mut self, seal_key_raw: SafeCell<Vec<u8>>) -> Result<(), Error> {
         if !matches!(self.state, State::Unbootstrapped) {
@@ -272,22 +251,6 @@ impl KeyHolder {
         Ok(())
     }
 
-    // Signs a generic integrity payload using the vault-derived integrity key
-    #[message]
-    pub fn sign_integrity_tag(
-        &mut self,
-        purpose_tag: Vec<u8>,
-        data_parts: Vec<Vec<u8>>,
-    ) -> Result<Vec<u8>, Error> {
-        let State::Unsealed { root_key, .. } = &mut self.state else {
-            return Err(Error::NotBootstrapped);
-        };
-
-        let tag =
-            compute_integrity_tag(root_key, &purpose_tag, data_parts.iter().map(Vec::as_slice));
-        Ok(tag.to_vec())
-    }
-
     #[message]
     pub async fn decrypt(&mut self, aead_id: i32) -> Result<SafeCell<Vec<u8>>, Error> {
         let State::Unsealed { root_key, .. } = &mut self.state else {
@@ -371,12 +334,12 @@ impl KeyHolder {
             return Err(Error::NotBootstrapped);
         };
 
-        let integrity_key = Self::derive_integrity_key(root_key);
-
-        let mut hmac = match HmacSha256::new_from_slice(&integrity_key) {
-            Ok(v) => v,
-            Err(_) => unreachable!("HMAC accepts keys of any size"),
-        };
+        let mut hmac = root_key
+            .0
+            .read_inline(|k| match HmacSha256::new_from_slice(k) {
+                Ok(v) => v,
+                Err(_) => unreachable!("HMAC accepts keys of any size"),
+            });
         hmac.update(&root_key_history_id.to_be_bytes());
         hmac.update(&mac_input);
 
@@ -403,11 +366,12 @@ impl KeyHolder {
             return Ok(false);
         }
 
-        let integrity_key = Self::derive_integrity_key(root_key);
-        let mut hmac = match HmacSha256::new_from_slice(&integrity_key) {
-            Ok(v) => v,
-            Err(_) => unreachable!("HMAC accepts keys of any size"),
-        };
+        let mut hmac = root_key
+            .0
+            .read_inline(|k| match HmacSha256::new_from_slice(k) {
+                Ok(v) => v,
+                Err(_) => unreachable!("HMAC accepts keys of any size"),
+            });
         hmac.update(&key_version.to_be_bytes());
         hmac.update(&mac_input);
 

server/crates/arbiter-server/src/actors/user_agent/auth.rs

@@ -37,6 +37,13 @@ impl Error {
     }
 }
 
+impl From<diesel::result::Error> for Error {
+    fn from(e: diesel::result::Error) -> Self {
+        error!(?e, "Database error");
+        Self::internal("Database error")
+    }
+}
+
 #[derive(Debug, Clone)]
 pub enum Outbound {
     AuthChallenge { nonce: i32 },

server/crates/arbiter-server/src/actors/user_agent/auth/state.rs

@@ -1,27 +1,20 @@
 use arbiter_proto::transport::Bi;
 use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, update};
-use diesel_async::RunQueryDsl;
-use kameo::error::SendError;
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use kameo::{actor::ActorRef, error::SendError};
 use tracing::error;
 
 use super::Error;
 use crate::{
     actors::{
         bootstrap::ConsumeToken,
-        keyholder::{self, SignIntegrityTag},
-        user_agent::{AuthPublicKey, UserAgentConnection, auth::Outbound},
+        keyholder::KeyHolder,
+        user_agent::{AuthPublicKey, UserAgentConnection, UserAgentCredentials, auth::Outbound},
     },
-    crypto::integrity::v1::USERAGENT_INTEGRITY_TAG,
-    db::schema,
+    crypto::integrity::{self, AttestationStatus},
+    db::{DatabasePool, schema::useragent_client},
 };
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum AttestationStatus {
-    Attested,
-    NotAttested,
-    Unavailable,
-}
-
 pub struct ChallengeRequest {
     pub pubkey: AuthPublicKey,
 }
@@ -50,11 +43,11 @@ smlang::statemachine!(
     }
 );
 
-async fn create_nonce(
-    db: &crate::db::DatabasePool,
-    pubkey_bytes: &[u8],
-    key_type: crate::db::models::KeyType,
-) -> Result<i32, Error> {
+/// Returns the current nonce, ready to use for the challenge nonce.
+async fn get_current_nonce_and_id(
+    db: &DatabasePool,
+    key: &AuthPublicKey,
+) -> Result<(i32, i32), Error> {
     let mut db_conn = db.get().await.map_err(|e| {
         error!(error = ?e, "Database pool error");
         Error::internal("Database unavailable")
@@ -62,21 +55,12 @@ async fn create_nonce(
     db_conn
         .exclusive_transaction(|conn| {
             Box::pin(async move {
-                let current_nonce = schema::useragent_client::table
-                    .filter(schema::useragent_client::public_key.eq(pubkey_bytes.to_vec()))
-                    .filter(schema::useragent_client::key_type.eq(key_type))
-                    .select(schema::useragent_client::nonce)
-                    .first::<i32>(conn)
-                    .await?;
-
-                update(schema::useragent_client::table)
-                    .filter(schema::useragent_client::public_key.eq(pubkey_bytes.to_vec()))
-                    .filter(schema::useragent_client::key_type.eq(key_type))
-                    .set(schema::useragent_client::nonce.eq(current_nonce + 1))
-                    .execute(conn)
-                    .await?;
-
-                Result::<_, diesel::result::Error>::Ok(current_nonce)
+                useragent_client::table
+                    .filter(useragent_client::public_key.eq(key.to_stored_bytes()))
+                    .filter(useragent_client::key_type.eq(key.key_type()))
+                    .select((useragent_client::id, useragent_client::nonce))
+                    .first::<(i32, i32)>(conn)
+                    .await
             })
         })
         .await
@@ -86,15 +70,98 @@ async fn create_nonce(
             Error::internal("Database operation failed")
         })?
         .ok_or_else(|| {
-            error!(?pubkey_bytes, "Public key not found in database");
+            error!(?key, "Public key not found in database");
             Error::UnregisteredPublicKey
         })
 }
 
-async fn register_key(
-    db: &crate::db::DatabasePool,
+async fn verify_integrity(
+    db: &DatabasePool,
+    keyholder: &ActorRef<KeyHolder>,
+    pubkey: &AuthPublicKey,
+) -> 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,
+        keyholder,
+        &UserAgentCredentials {
+            pubkey: pubkey.clone(),
+            nonce,
+        },
+        id,
+    )
+    .await
+    .map_err(|e| {
+        error!(?e, "Integrity verification failed");
+        Error::internal("Integrity verification failed")
+    })?;
+
+    match result {
+        AttestationStatus::Attested | AttestationStatus::Unavailable => Ok(()),
+        AttestationStatus::NotAttested => {
+            error!(?pubkey, "Integrity verification failed: not attested");
+            Err(Error::internal("Database tampering detected"))
+        }
+    }
+
+}
+
+async fn create_nonce(
+    db: &DatabasePool,
+    keyholder: &ActorRef<KeyHolder>,
+    pubkey: &AuthPublicKey,
+) -> Result<i32, Error> {
+    let mut db_conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::internal("Database unavailable")
+    })?;
+    let new_nonce = db_conn
+        .exclusive_transaction(|conn| {
+            Box::pin(async move {
+                let (id, new_nonce): (i32, i32) = update(useragent_client::table)
+                    .filter(useragent_client::public_key.eq(pubkey.to_stored_bytes()))
+                    .filter(useragent_client::key_type.eq(pubkey.key_type()))
+                    .set(useragent_client::nonce.eq(useragent_client::nonce + 1))
+                    .returning((useragent_client::id, useragent_client::nonce))
+                    .get_result(conn)
+                    .await
+                    .map_err(|e| {
+                        error!(error = ?e, "Database error");
+                        Error::internal("Database operation failed")
+                    })?;
+
+                integrity::sign_entity(
+                    conn,
+                    keyholder,
+                    &UserAgentCredentials {
+                        pubkey: pubkey.clone(),
+                        nonce: new_nonce,
+                    },
+                    id,
+                )
+                .await
+                .map_err(|e| {
+                    error!(?e, "Integrity signature update failed");
+                    Error::internal("Database error")
+                })?;
+
+                Result::<_, Error>::Ok(new_nonce)
+            })
+        })
+        .await?;
+    Ok(new_nonce)
+}
+
+async fn register_key(
+    db: &DatabasePool,
+    keyholder: &ActorRef<KeyHolder>,
     pubkey: &AuthPublicKey,
-    integrity_tag: Option<Vec<u8>>,
 ) -> Result<(), Error> {
     let pubkey_bytes = pubkey.to_stored_bytes();
     let key_type = pubkey.key_type();
@@ -103,19 +170,40 @@ async fn register_key(
         Error::internal("Database unavailable")
     })?;
 
-    diesel::insert_into(schema::useragent_client::table)
-        .values((
-            schema::useragent_client::public_key.eq(pubkey_bytes),
-            schema::useragent_client::nonce.eq(1),
-            schema::useragent_client::key_type.eq(key_type),
-            schema::useragent_client::pubkey_integrity_tag.eq(integrity_tag),
-        ))
-        .execute(&mut conn)
-        .await
-        .map_err(|e| {
-            error!(error = ?e, "Database error");
-            Error::internal("Database operation failed")
-        })?;
+    conn.transaction(|conn| {
+        Box::pin(async move {
+            const NONCE_START: i32 = 1;
+
+            let id: i32 = diesel::insert_into(useragent_client::table)
+                .values((
+                    useragent_client::public_key.eq(pubkey_bytes),
+                    useragent_client::nonce.eq(NONCE_START),
+                    useragent_client::key_type.eq(key_type),
+                ))
+                .returning(useragent_client::id)
+                .get_result(conn)
+                .await
+                .map_err(|e| {
+                    error!(error = ?e, "Database error");
+                    Error::internal("Database operation failed")
+                })?;
+
+            let entity = UserAgentCredentials {
+                pubkey: pubkey.clone(),
+                nonce: NONCE_START,
+            };
+
+            integrity::sign_entity(conn, &keyholder, &entity, id)
+                .await
+                .map_err(|e| {
+                    error!(error = ?e, "Failed to sign integrity tag for new user-agent key");
+                    Error::internal("Failed to register public key")
+                })?;
+
+            Result::<_, Error>::Ok(())
+        })
+    })
+    .await?;
 
     Ok(())
 }
@@ -141,15 +229,9 @@ where
         &mut self,
         ChallengeRequest { pubkey }: ChallengeRequest,
     ) -> Result<ChallengeContext, Self::Error> {
-        match self.verify_pubkey_attestation_status(&pubkey).await? {
-            AttestationStatus::Attested | AttestationStatus::Unavailable => {}
-            AttestationStatus::NotAttested => {
-                return Err(Error::InvalidChallengeSolution);
-            }
-        }
+        verify_integrity(&self.conn.db, &self.conn.actors.key_holder, &pubkey).await?;
 
-        let stored_bytes = pubkey.to_stored_bytes();
-        let nonce = create_nonce(&self.conn.db, &stored_bytes, pubkey.key_type()).await?;
+        let nonce = create_nonce(&self.conn.db, &self.conn.actors.key_holder, &pubkey).await?;
 
         self.transport
             .send(Ok(Outbound::AuthChallenge { nonce }))
@@ -189,22 +271,24 @@ where
             return Err(Error::InvalidBootstrapToken);
         }
 
-        let integrity_tag = self
-            .try_sign_pubkey_integrity_tag(&pubkey)
-            .await
-            .map_err(|err| {
-                error!(?err, "Failed to sign user-agent pubkey integrity tag");
-                Error::internal("Failed to sign user-agent pubkey integrity tag")
-            })?;
-
-        register_key(&self.conn.db, &pubkey, integrity_tag).await?;
-
-        self.transport
-            .send(Ok(Outbound::AuthSuccess))
-            .await
-            .map_err(|_| Error::Transport)?;
-
-        Ok(pubkey)
+        match token_ok {
+            true => {
+                register_key(&self.conn.db, &self.conn.actors.key_holder, &pubkey).await?;
+                self.transport
+                    .send(Ok(Outbound::AuthSuccess))
+                    .await
+                    .map_err(|_| Error::Transport)?;
+                Ok(pubkey)
+            }
+            false => {
+                error!("Invalid bootstrap token provided");
+                self.transport
+                    .send(Err(Error::InvalidBootstrapToken))
+                    .await
+                    .map_err(|_| Error::Transport)?;
+                Err(Error::InvalidBootstrapToken)
+            }
+        }
     }
 
     #[allow(missing_docs)]
@@ -264,93 +348,3 @@ where
         }
     }
 }
-
-impl<T> AuthContext<'_, T>
-where
-    T: Bi<super::Inbound, Result<super::Outbound, Error>> + Send,
-{
-    async fn try_sign_pubkey_integrity_tag(
-        &self,
-        pubkey: &AuthPublicKey,
-    ) -> Result<Option<Vec<u8>>, Error> {
-        let signed = self
-            .conn
-            .actors
-            .key_holder
-            .ask(SignIntegrityTag {
-                purpose_tag: USERAGENT_INTEGRITY_TAG.to_vec(),
-                data_parts: vec![
-                    (pubkey.key_type() as i32).to_be_bytes().to_vec(),
-                    pubkey.to_stored_bytes(),
-                ],
-            })
-            .await;
-
-        match signed {
-            Ok(tag) => Ok(Some(tag)),
-            Err(SendError::HandlerError(keyholder::Error::NotBootstrapped)) => Ok(None),
-            Err(SendError::HandlerError(err)) => {
-                error!(
-                    ?err,
-                    "Keyholder failed to sign user-agent pubkey integrity tag"
-                );
-                Err(Error::internal(
-                    "Keyholder failed to sign user-agent pubkey integrity tag",
-                ))
-            }
-            Err(err) => {
-                error!(
-                    ?err,
-                    "Failed to contact keyholder for user-agent pubkey integrity tag"
-                );
-                Err(Error::internal(
-                    "Failed to contact keyholder for user-agent pubkey integrity tag",
-                ))
-            }
-        }
-    }
-
-    async fn verify_pubkey_attestation_status(
-        &self,
-        pubkey: &AuthPublicKey,
-    ) -> Result<AttestationStatus, Error> {
-        let stored_tag: Option<Option<Vec<u8>>> = {
-            let mut conn = self.conn.db.get().await.map_err(|e| {
-                error!(error = ?e, "Database pool error");
-                Error::internal("Database unavailable")
-            })?;
-
-            schema::useragent_client::table
-                .filter(schema::useragent_client::public_key.eq(pubkey.to_stored_bytes()))
-                .filter(schema::useragent_client::key_type.eq(pubkey.key_type()))
-                .select(schema::useragent_client::pubkey_integrity_tag)
-                .first::<Option<Vec<u8>>>(&mut conn)
-                .await
-                .optional()
-                .map_err(|e| {
-                    error!(error = ?e, "Database error");
-                    Error::internal("Database operation failed")
-                })?
-        };
-
-        let Some(stored_tag) = stored_tag else {
-            return Err(Error::UnregisteredPublicKey);
-        };
-
-        let Some(expected_tag) = self.try_sign_pubkey_integrity_tag(pubkey).await? else {
-            return Ok(AttestationStatus::Unavailable);
-        };
-
-        match stored_tag {
-            Some(stored_tag) if stored_tag == expected_tag => Ok(AttestationStatus::Attested),
-            Some(_) => {
-                error!("User-agent pubkey integrity tag mismatch");
-                Ok(AttestationStatus::NotAttested)
-            }
-            None => {
-                error!("Missing pubkey integrity tag for registered key while vault is unsealed");
-                Ok(AttestationStatus::NotAttested)
-            }
-        }
-    }
-}

server/crates/arbiter-server/src/actors/user_agent/mod.rs

@@ -1,18 +1,65 @@
 use crate::{
-    actors::{GlobalActors, client::ClientProfile},
-    db::{self, models::KeyType},
+    actors::{GlobalActors, client::ClientProfile}, crypto::integrity::Integrable, db::{self, models::KeyType}
 };
 
+fn serialize_ecdsa<S>(key: &k256::ecdsa::VerifyingKey, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: serde::Serializer,
+{
+    // Serialize as hex string for easier debugging (33 bytes compressed SEC1 format)
+    let key = key.to_encoded_point(true);
+    let bytes = key.as_bytes();
+    serializer.serialize_bytes(bytes)
+}
+
+fn deserialize_ecdsa<'de, D>(deserializer: D) -> Result<k256::ecdsa::VerifyingKey, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    struct EcdsaVisitor;
+
+    impl<'de> serde::de::Visitor<'de> for EcdsaVisitor {
+        type Value = k256::ecdsa::VerifyingKey;
+
+        fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+            formatter.write_str("a compressed SEC1-encoded ECDSA public key")
+        }
+
+        fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
+        where
+            E: serde::de::Error,
+        {
+            let point = k256::EncodedPoint::from_bytes(v)
+                .map_err(|_| E::custom("invalid compressed SEC1 format"))?;
+            k256::ecdsa::VerifyingKey::from_encoded_point(&point)
+                .map_err(|_| E::custom("invalid ECDSA public key"))
+        }
+    }
+
+    deserializer.deserialize_bytes(EcdsaVisitor)
+}
+
 /// Abstraction over Ed25519 / ECDSA-secp256k1 / RSA public keys used during the auth handshake.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Serialize)]
 pub enum AuthPublicKey {
     Ed25519(ed25519_dalek::VerifyingKey),
     /// Compressed SEC1 public key; signature bytes are raw 64-byte (r||s).
+    #[serde(serialize_with = "serialize_ecdsa", deserialize_with = "deserialize_ecdsa")]
     EcdsaSecp256k1(k256::ecdsa::VerifyingKey),
     /// RSA-2048+ public key (Windows Hello / KeyCredentialManager); signature bytes are PSS+SHA-256.
     Rsa(rsa::RsaPublicKey),
 }
 
+#[derive(Debug, Serialize)]
+pub struct UserAgentCredentials {
+    pub pubkey: AuthPublicKey,
+    pub nonce: i32
+}
+
+impl Integrable for UserAgentCredentials {
+    const KIND: &'static str = "useragent_credentials";
+}
+
 impl AuthPublicKey {
     /// Canonical bytes stored in DB and echoed back in the challenge.
     /// Ed25519: raw 32 bytes. ECDSA: SEC1 compressed 33 bytes. RSA: DER-encoded SPKI.
@@ -91,4 +138,5 @@ pub mod auth;
 pub mod session;
 
 pub use auth::authenticate;
+use serde::Serialize;
 pub use session::UserAgentSession;

server/crates/arbiter-server/src/actors/user_agent/session/connection.rs

@@ -349,9 +349,6 @@ impl UserAgentSession {
             .await
         {
             Ok(grant_id) => Ok(grant_id),
-            Err(SendError::HandlerError(crate::actors::evm::Error::VaultSealed)) => {
-                Err(GrantMutationError::VaultSealed)
-            }
             Err(err) => {
                 error!(?err, "EVM grant create failed");
                 Err(GrantMutationError::Internal)
@@ -372,9 +369,6 @@ impl UserAgentSession {
             .await
         {
             Ok(()) => Ok(()),
-            Err(SendError::HandlerError(crate::actors::evm::Error::VaultSealed)) => {
-                Err(GrantMutationError::VaultSealed)
-            }
             Err(err) => {
                 error!(?err, "EVM grant delete failed");
                 Err(GrantMutationError::Internal)