Pin announce signing keys to stop mesh identity spoofing (#1349)

TOFU-pins the Ed25519 signing key per noise key so a self-consistent announce that reuses a victim's peerID+noise key with the attacker's signing key/nickname is rejected instead of overwriting the registry and persisted identity. Complements #1432: that PR's signed-LEAVE verification reads the stored signing key this PR protects from announce-path poisoning. Rebased onto main as a single commit; swift build --build-tests green, 40/40 targeted tests incl. the spoofing e2e cases, and #1432's suites 50/50 unaffected.
2026-07-27 15:25:22 +00:00 · 2026-07-26 11:38:24 +02:00
parent d326cecb63
commit b96a41054e
11 changed files with 885 additions and 76 deletions
@@ -6,10 +6,13 @@ import Testing
 struct BLEAnnounceHandlerTests {
    private final class Recorder {
        var existingNoisePublicKey: Data?
+        var existingSigningPublicKey: Data?
+        var persistedSigningPublicKey: Data?
+        var persistedSigningKeyQueries: [PeerID] = []
        var signatureValid = true
        var linkState: (hasPeripheral: Bool, hasCentral: Bool) = (false, false)
        var linkBoundToOtherPeer = false
-        var upsertResult = BLEPeerAnnounceUpdate(isNewPeer: false, wasDisconnected: false, previousNickname: nil)
+        var upsertResult: BLEPeerAnnounceUpdate? = BLEPeerAnnounceUpdate(isNewPeer: false, wasDisconnected: false, previousNickname: nil)
        var dedupSeenIDs: Set<String> = []
        var shouldEmitReconnectLogResult = true

@@ -36,7 +39,11 @@ struct BLEAnnounceHandlerTests {
            localPeerID: { localPeerID },
            messageTTL: TransportConfig.messageTTLDefault,
            now: { now },
-            existingNoisePublicKey: { _ in recorder.existingNoisePublicKey },
+            existingPeerKeys: { _ in (recorder.existingNoisePublicKey, recorder.existingSigningPublicKey) },
+            persistedSigningPublicKey: { peerID in
+                recorder.persistedSigningKeyQueries.append(peerID)
+                return recorder.persistedSigningPublicKey
+            },
            verifySignature: { packet, signingPublicKey in
                recorder.verifySignatureCalls.append((packet, signingPublicKey))
                return recorder.signatureValid
@@ -482,6 +489,168 @@ struct BLEAnnounceHandlerTests {
        #expect(recorder.topologyUpdates.first?.neighbors == neighbors)
    }

+    @Test
+    func matchingPinnedSigningKeyIsAccepted() throws {
+        let now = Date(timeIntervalSince1970: 1_000)
+        let noiseKey = Data(repeating: 0x9A, count: 32)
+        let peerID = PeerID(publicKey: noiseKey)
+        let packet = try makeAnnouncePacket(
+            noisePublicKey: noiseKey,
+            peerID: peerID,
+            timestamp: timestamp(now),
+            signature: Data(repeating: 0xEE, count: 64)
+        )
+
+        let recorder = Recorder()
+        recorder.existingNoisePublicKey = noiseKey
+        // Matches the signing key encoded by makeAnnouncePacket.
+        recorder.existingSigningPublicKey = Data(repeating: 0x99, count: 32)
+        let handler = makeHandler(recorder: recorder, now: now)
+
+        handler.handle(packet, from: peerID)
+
+        #expect(recorder.upsertCalls.count == 1)
+        #expect(recorder.persistedIdentities.count == 1)
+    }
+
+    @Test
+    func signingKeyMismatchWithPinnedKeySkipsUpsertAndIdentityPersistence() throws {
+        let now = Date(timeIntervalSince1970: 1_000)
+        let noiseKey = Data(repeating: 0x9B, count: 32)
+        let peerID = PeerID(publicKey: noiseKey)
+        // Attacker announce: victim's noiseKey/peerID, attacker's signing key
+        // (0x99 from makeAnnouncePacket) with a "valid" self-signature.
+        let packet = try makeAnnouncePacket(
+            noisePublicKey: noiseKey,
+            peerID: peerID,
+            timestamp: timestamp(now),
+            signature: Data(repeating: 0xEE, count: 64)
+        )
+
+        let recorder = Recorder()
+        recorder.existingNoisePublicKey = noiseKey
+        recorder.existingSigningPublicKey = Data(repeating: 0x42, count: 32) // victim's pinned key
+        recorder.signatureValid = true
+        let handler = makeHandler(recorder: recorder, now: now)
+
+        handler.handle(packet, from: peerID)
+
+        #expect(recorder.upsertCalls.isEmpty)
+        #expect(recorder.persistedIdentities.isEmpty)
+        #expect(recorder.topologyUpdates.isEmpty)
+        #expect(recorder.uiEventDeliveries.count == 1)
+        #expect(recorder.uiEventDeliveries.first?.notifyPeerConnected == false)
+    }
+
+    @Test
+    func persistedSigningKeyMismatchWithoutRegistryEntryIsRejected() throws {
+        // Registry has no entry (app restart or offline-peer eviction), but
+        // the persisted cryptographic identity still pins the victim's
+        // signing key. An attacker replaying the victim's noiseKey/peerID
+        // with their own signing key must not be treated as first contact.
+        let now = Date(timeIntervalSince1970: 1_000)
+        let noiseKey = Data(repeating: 0x9D, count: 32)
+        let peerID = PeerID(publicKey: noiseKey)
+        let packet = try makeAnnouncePacket(
+            noisePublicKey: noiseKey,
+            peerID: peerID,
+            timestamp: timestamp(now),
+            signature: Data(repeating: 0xEE, count: 64)
+        )
+
+        let recorder = Recorder()
+        recorder.existingNoisePublicKey = nil
+        recorder.existingSigningPublicKey = nil
+        recorder.persistedSigningPublicKey = Data(repeating: 0x42, count: 32) // victim's persisted pin
+        let handler = makeHandler(recorder: recorder, now: now)
+
+        handler.handle(packet, from: peerID)
+
+        #expect(recorder.persistedSigningKeyQueries == [peerID])
+        #expect(recorder.upsertCalls.isEmpty)
+        #expect(recorder.persistedIdentities.isEmpty)
+        #expect(recorder.topologyUpdates.isEmpty)
+        #expect(recorder.uiEventDeliveries.count == 1)
+        #expect(recorder.uiEventDeliveries.first?.notifyPeerConnected == false)
+    }
+
+    @Test
+    func persistedSigningKeyMatchWithoutRegistryEntryIsAccepted() throws {
+        // Legitimate returning peer: registry entry evicted, persisted pin
+        // matches the announced signing key — accepted like a normal announce.
+        let now = Date(timeIntervalSince1970: 1_000)
+        let noiseKey = Data(repeating: 0x9E, count: 32)
+        let peerID = PeerID(publicKey: noiseKey)
+        let packet = try makeAnnouncePacket(
+            noisePublicKey: noiseKey,
+            peerID: peerID,
+            timestamp: timestamp(now),
+            signature: Data(repeating: 0xEE, count: 64)
+        )
+
+        let recorder = Recorder()
+        // Matches the signing key encoded by makeAnnouncePacket.
+        recorder.persistedSigningPublicKey = Data(repeating: 0x99, count: 32)
+        let handler = makeHandler(recorder: recorder, now: now)
+
+        handler.handle(packet, from: peerID)
+
+        #expect(recorder.upsertCalls.count == 1)
+        #expect(recorder.persistedIdentities.count == 1)
+    }
+
+    @Test
+    func registryPinnedSigningKeySkipsPersistedLookup() throws {
+        let now = Date(timeIntervalSince1970: 1_000)
+        let noiseKey = Data(repeating: 0x9F, count: 32)
+        let peerID = PeerID(publicKey: noiseKey)
+        let packet = try makeAnnouncePacket(
+            noisePublicKey: noiseKey,
+            peerID: peerID,
+            timestamp: timestamp(now),
+            signature: Data(repeating: 0xEE, count: 64)
+        )
+
+        let recorder = Recorder()
+        recorder.existingNoisePublicKey = noiseKey
+        recorder.existingSigningPublicKey = Data(repeating: 0x99, count: 32)
+        let handler = makeHandler(recorder: recorder, now: now)
+
+        handler.handle(packet, from: peerID)
+
+        #expect(recorder.persistedSigningKeyQueries.isEmpty)
+        #expect(recorder.upsertCalls.count == 1)
+    }
+
+    @Test
+    func registryPinRejectionSkipsTopologyAndIdentityPersistence() throws {
+        let now = Date(timeIntervalSince1970: 1_000)
+        let noiseKey = Data(repeating: 0x9C, count: 32)
+        let peerID = PeerID(publicKey: noiseKey)
+        let packet = try makeAnnouncePacket(
+            noisePublicKey: noiseKey,
+            peerID: peerID,
+            timestamp: timestamp(now),
+            signature: Data(repeating: 0xEE, count: 64),
+            directNeighbors: [Data(repeating: 0xAB, count: 8)]
+        )
+
+        // Pre-barrier trust check sees no pinned key (e.g. concurrent race),
+        // but the registry itself refuses to replace its pinned signing key.
+        let recorder = Recorder()
+        recorder.upsertResult = nil
+        let handler = makeHandler(recorder: recorder, now: now)
+
+        handler.handle(packet, from: peerID)
+
+        #expect(recorder.upsertCalls.count == 1)
+        #expect(recorder.persistedIdentities.isEmpty)
+        #expect(recorder.topologyUpdates.isEmpty)
+        #expect(recorder.uiEventDeliveries.count == 1)
+        #expect(recorder.uiEventDeliveries.first?.notifyPeerConnected == false)
+        #expect(recorder.afterglowDelays.isEmpty)
+    }
+
    @Test
    func keyMismatchWithExistingPeerKeepsAnnounceUnverified() throws {
        let now = Date(timeIntervalSince1970: 1_000)
@@ -506,6 +675,253 @@ struct BLEAnnounceHandlerTests {
        #expect(recorder.uiEventDeliveries.first?.notifyPeerConnected == false)
    }

+    @Test
+    func attackerReplayingVictimNoiseKeyWithOwnSigningKeyIsRejectedEndToEnd() throws {
+        // Real crypto: the attacker crafts a fully self-consistent announce
+        // (victim's noiseKey/peerID, attacker's signing key and nickname,
+        // valid packet signature made with the attacker's key). Without
+        // signing-key pinning this used to overwrite the victim's registry
+        // entry and persisted identity.
+        let victim = NoiseEncryptionService(keychain: MockKeychain())
+        let attacker = NoiseEncryptionService(keychain: MockKeychain())
+        let victimNoiseKey = victim.getStaticPublicKeyData()
+        let peerID = PeerID(publicKey: victimNoiseKey)
+        let now = Date()
+
+        final class RegistryBox {
+            var registry = BLEPeerRegistry()
+            var persistedIdentities: [AnnouncementPacket] = []
+        }
+        let box = RegistryBox()
+
+        let environment = BLEAnnounceHandlerEnvironment(
+            localPeerID: { PeerID(str: "0102030405060708") },
+            messageTTL: TransportConfig.messageTTLDefault,
+            now: { now },
+            existingPeerKeys: { peerID in
+                let info = box.registry.info(for: peerID)
+                return (info?.noisePublicKey, info?.signingPublicKey)
+            },
+            persistedSigningPublicKey: { _ in nil },
+            verifySignature: { packet, signingPublicKey in
+                victim.verifyPacketSignature(packet, publicKey: signingPublicKey)
+            },
+            linkState: { _ in (hasPeripheral: true, hasCentral: false) },
+            linkBoundToOtherPeer: { _, _ in false },
+            withRegistryBarrier: { body in body() },
+            upsertVerifiedAnnounce: { peerID, announcement, isConnected, now in
+                box.registry.upsertVerifiedAnnounce(
+                    peerID: peerID,
+                    nickname: announcement.nickname,
+                    noisePublicKey: announcement.noisePublicKey,
+                    signingPublicKey: announcement.signingPublicKey,
+                    isConnected: isConnected,
+                    now: now
+                )
+            },
+            shouldEmitReconnectLog: { _, _ in false },
+            updateTopology: { _, _ in },
+            persistIdentity: { announcement in
+                box.persistedIdentities.append(announcement)
+            },
+            dedupContains: { _ in true },
+            dedupMarkProcessed: { _ in },
+            deliverAnnounceUIEvents: { _, _, _ in },
+            trackPacketSeen: { _ in },
+            sendAnnounceBack: {},
+            scheduleAfterglow: { _ in }
+        )
+        let handler = BLEAnnounceHandler(environment: environment)
+
+        func makeSignedAnnounce(nickname: String, signer: NoiseEncryptionService) throws -> BitchatPacket {
+            let announcement = AnnouncementPacket(
+                nickname: nickname,
+                noisePublicKey: victimNoiseKey,
+                signingPublicKey: signer.getSigningPublicKeyData(),
+                directNeighbors: nil
+            )
+            let payload = try #require(announcement.encode())
+            let packet = BitchatPacket(
+                type: MessageType.announce.rawValue,
+                senderID: Data(hexString: peerID.id) ?? Data(),
+                recipientID: nil,
+                timestamp: UInt64(now.timeIntervalSince1970 * 1000),
+                payload: payload,
+                signature: nil,
+                ttl: TransportConfig.messageTTLDefault
+            )
+            return try #require(signer.signPacket(packet))
+        }
+
+        // Legitimate announce from the victim is accepted and pinned.
+        let victimAnnounce = try makeSignedAnnounce(nickname: "victim", signer: victim)
+        handler.handle(victimAnnounce, from: peerID)
+
+        #expect(box.registry.info(for: peerID)?.nickname == "victim")
+        #expect(box.registry.info(for: peerID)?.signingPublicKey == victim.getSigningPublicKeyData())
+        #expect(box.persistedIdentities.count == 1)
+
+        // Attacker announce with a valid self-signature must be rejected.
+        let attackerAnnounce = try makeSignedAnnounce(nickname: "attacker", signer: attacker)
+        handler.handle(attackerAnnounce, from: peerID)
+
+        #expect(box.registry.info(for: peerID)?.nickname == "victim")
+        #expect(box.registry.info(for: peerID)?.signingPublicKey == victim.getSigningPublicKeyData())
+        #expect(box.persistedIdentities.count == 1)
+
+        // The victim's subsequent announces (same pinned key) still work.
+        let victimRename = try makeSignedAnnounce(nickname: "victim-renamed", signer: victim)
+        handler.handle(victimRename, from: peerID)
+
+        #expect(box.registry.info(for: peerID)?.nickname == "victim-renamed")
+        #expect(box.persistedIdentities.count == 2)
+    }
+
+    @Test
+    func signingKeyPinSurvivesRegistryEvictionAndRestartEndToEnd() throws {
+        // Real crypto + real persistence: the victim announces and gets
+        // pinned, then the registry entry disappears (offline-peer eviction
+        // via reconcileConnectivity, or app restart which starts with an
+        // empty registry). The attacker replays the victim's
+        // noiseKey/peerID with their own signing key and a valid
+        // self-signature — the persisted identity must still block the
+        // takeover, and must not be overwritten. The victim (same signing
+        // key) must be re-accepted.
+        let victim = NoiseEncryptionService(keychain: MockKeychain())
+        let attacker = NoiseEncryptionService(keychain: MockKeychain())
+        let victimNoiseKey = victim.getStaticPublicKeyData()
+        let peerID = PeerID(publicKey: victimNoiseKey)
+        let now = Date()
+
+        let identityKeychain = MockKeychain()
+        let identityManager = SecureIdentityStateManager(identityKeychain)
+
+        final class RegistryBox {
+            var registry = BLEPeerRegistry()
+        }
+        let box = RegistryBox()
+
+        func makeEnvironment(identityManager: SecureIdentityStateManager) -> BLEAnnounceHandlerEnvironment {
+            BLEAnnounceHandlerEnvironment(
+                localPeerID: { PeerID(str: "0102030405060708") },
+                messageTTL: TransportConfig.messageTTLDefault,
+                now: { now },
+                existingPeerKeys: { peerID in
+                    let info = box.registry.info(for: peerID)
+                    return (info?.noisePublicKey, info?.signingPublicKey)
+                },
+                // Mirrors the BLEService wiring: fall back to the persisted
+                // cryptographic identity.
+                persistedSigningPublicKey: { peerID in
+                    identityManager.getCryptoIdentitiesByPeerIDPrefix(peerID)
+                        .compactMap { $0.signingPublicKey }
+                        .first
+                },
+                verifySignature: { packet, signingPublicKey in
+                    victim.verifyPacketSignature(packet, publicKey: signingPublicKey)
+                },
+                linkState: { _ in (hasPeripheral: true, hasCentral: false) },
+                linkBoundToOtherPeer: { _, _ in false },
+                withRegistryBarrier: { body in body() },
+                upsertVerifiedAnnounce: { peerID, announcement, isConnected, now in
+                    box.registry.upsertVerifiedAnnounce(
+                        peerID: peerID,
+                        nickname: announcement.nickname,
+                        noisePublicKey: announcement.noisePublicKey,
+                        signingPublicKey: announcement.signingPublicKey,
+                        isConnected: isConnected,
+                        now: now
+                    )
+                },
+                shouldEmitReconnectLog: { _, _ in false },
+                updateTopology: { _, _ in },
+                persistIdentity: { announcement in
+                    identityManager.upsertCryptographicIdentity(
+                        fingerprint: announcement.noisePublicKey.sha256Fingerprint(),
+                        noisePublicKey: announcement.noisePublicKey,
+                        signingPublicKey: announcement.signingPublicKey,
+                        claimedNickname: announcement.nickname
+                    )
+                },
+                dedupContains: { _ in true },
+                dedupMarkProcessed: { _ in },
+                deliverAnnounceUIEvents: { _, _, _ in },
+                trackPacketSeen: { _ in },
+                sendAnnounceBack: {},
+                scheduleAfterglow: { _ in }
+            )
+        }
+        let handler = BLEAnnounceHandler(environment: makeEnvironment(identityManager: identityManager))
+
+        func makeSignedAnnounce(nickname: String, signer: NoiseEncryptionService) throws -> BitchatPacket {
+            let announcement = AnnouncementPacket(
+                nickname: nickname,
+                noisePublicKey: victimNoiseKey,
+                signingPublicKey: signer.getSigningPublicKeyData(),
+                directNeighbors: nil
+            )
+            let payload = try #require(announcement.encode())
+            let packet = BitchatPacket(
+                type: MessageType.announce.rawValue,
+                senderID: Data(hexString: peerID.id) ?? Data(),
+                recipientID: nil,
+                timestamp: UInt64(now.timeIntervalSince1970 * 1000),
+                payload: payload,
+                signature: nil,
+                ttl: TransportConfig.messageTTLDefault
+            )
+            return try #require(signer.signPacket(packet))
+        }
+
+        func persistedIdentity() -> CryptographicIdentity? {
+            // queue.sync read; fences the manager's pending barrier writes.
+            identityManager.getCryptoIdentitiesByPeerIDPrefix(peerID).first
+        }
+
+        // 1. Victim announces: pinned in the registry and persisted.
+        handler.handle(try makeSignedAnnounce(nickname: "victim", signer: victim), from: peerID)
+        #expect(box.registry.info(for: peerID)?.signingPublicKey == victim.getSigningPublicKeyData())
+        #expect(persistedIdentity()?.signingPublicKey == victim.getSigningPublicKeyData())
+
+        // 2. Registry entry disappears (eviction / restart).
+        _ = box.registry.remove(peerID)
+        #expect(box.registry.info(for: peerID) == nil)
+
+        // 3. Attacker replay with own signing key: rejected via the persisted
+        //    pin, and neither the registry nor the persisted identity change.
+        handler.handle(try makeSignedAnnounce(nickname: "attacker", signer: attacker), from: peerID)
+        #expect(box.registry.info(for: peerID) == nil)
+        #expect(persistedIdentity()?.signingPublicKey == victim.getSigningPublicKeyData())
+        #expect(identityManager.getSocialIdentity(for: victimNoiseKey.sha256Fingerprint())?.claimedNickname == "victim")
+
+        // 4. Victim re-announces with the same signing key: accepted again.
+        handler.handle(try makeSignedAnnounce(nickname: "victim", signer: victim), from: peerID)
+        #expect(box.registry.info(for: peerID)?.nickname == "victim")
+        #expect(box.registry.info(for: peerID)?.signingPublicKey == victim.getSigningPublicKeyData())
+
+        // 5. Simulated app restart: a fresh identity manager reloads the pin
+        //    from the (mock) keychain, and a fresh registry starts empty. The
+        //    attacker replay is still rejected.
+        identityManager.forceSave()
+        let reloadedManager = SecureIdentityStateManager(identityKeychain)
+        #expect(
+            reloadedManager.getCryptoIdentitiesByPeerIDPrefix(peerID).first?.signingPublicKey
+                == victim.getSigningPublicKeyData()
+        )
+        box.registry = BLEPeerRegistry()
+        let restartedHandler = BLEAnnounceHandler(environment: makeEnvironment(identityManager: reloadedManager))
+        restartedHandler.handle(try makeSignedAnnounce(nickname: "attacker", signer: attacker), from: peerID)
+        #expect(box.registry.info(for: peerID) == nil)
+        #expect(
+            reloadedManager.getCryptoIdentitiesByPeerIDPrefix(peerID).first?.signingPublicKey
+                == victim.getSigningPublicKeyData()
+        )
+
+        // ...while the victim is accepted after the restart.
+        restartedHandler.handle(try makeSignedAnnounce(nickname: "victim", signer: victim), from: peerID)
+        #expect(box.registry.info(for: peerID)?.signingPublicKey == victim.getSigningPublicKeyData())
+    }
+
    private func expectNoSideEffects(_ recorder: Recorder) {
        #expect(recorder.barrierCount == 0)
        #expect(recorder.upsertCalls.isEmpty)
@@ -123,7 +123,9 @@ struct BLEAnnounceHandlingPolicyTests {
            hasSignature: false,
            signatureValid: false,
            existingNoisePublicKey: nil,
-            announcedNoisePublicKey: Data(repeating: 0x11, count: 32)
+            announcedNoisePublicKey: Data(repeating: 0x11, count: 32),
+            existingSigningPublicKey: nil,
+            announcedSigningPublicKey: Data(repeating: 0x99, count: 32)
        )

        #expect(decision == .reject(.missingSignature))
@@ -136,7 +138,9 @@ struct BLEAnnounceHandlingPolicyTests {
            hasSignature: true,
            signatureValid: false,
            existingNoisePublicKey: nil,
-            announcedNoisePublicKey: Data(repeating: 0x11, count: 32)
+            announcedNoisePublicKey: Data(repeating: 0x11, count: 32),
+            existingSigningPublicKey: nil,
+            announcedSigningPublicKey: Data(repeating: 0x99, count: 32)
        )

        #expect(decision == .reject(.invalidSignature))
@@ -148,7 +152,9 @@ struct BLEAnnounceHandlingPolicyTests {
            hasSignature: true,
            signatureValid: true,
            existingNoisePublicKey: Data(repeating: 0xAA, count: 32),
-            announcedNoisePublicKey: Data(repeating: 0xBB, count: 32)
+            announcedNoisePublicKey: Data(repeating: 0xBB, count: 32),
+            existingSigningPublicKey: nil,
+            announcedSigningPublicKey: Data(repeating: 0x99, count: 32)
        )

        #expect(decision == .reject(.keyMismatch))
@@ -162,13 +168,51 @@ struct BLEAnnounceHandlingPolicyTests {
            hasSignature: true,
            signatureValid: true,
            existingNoisePublicKey: noiseKey,
-            announcedNoisePublicKey: noiseKey
+            announcedNoisePublicKey: noiseKey,
+            existingSigningPublicKey: nil,
+            announcedSigningPublicKey: Data(repeating: 0x99, count: 32)
        )

        #expect(decision == .verified)
        #expect(decision.isVerified)
    }

+    @Test
+    func trustPolicyRejectsPinnedSigningKeyMismatchEvenWithValidSignature() {
+        let noiseKey = Data(repeating: 0xCC, count: 32)
+
+        // Attacker replays the victim's noiseKey/peerID with their own signing
+        // key and a valid self-signature; the pinned key must win.
+        let decision = BLEAnnounceTrustPolicy.evaluate(
+            hasSignature: true,
+            signatureValid: true,
+            existingNoisePublicKey: noiseKey,
+            announcedNoisePublicKey: noiseKey,
+            existingSigningPublicKey: Data(repeating: 0x99, count: 32),
+            announcedSigningPublicKey: Data(repeating: 0x66, count: 32)
+        )
+
+        #expect(decision == .reject(.signingKeyMismatch))
+        #expect(!decision.isVerified)
+    }
+
+    @Test
+    func trustPolicyAcceptsMatchingPinnedSigningKey() {
+        let noiseKey = Data(repeating: 0xCC, count: 32)
+        let signingKey = Data(repeating: 0x99, count: 32)
+
+        let decision = BLEAnnounceTrustPolicy.evaluate(
+            hasSignature: true,
+            signatureValid: true,
+            existingNoisePublicKey: noiseKey,
+            announcedNoisePublicKey: noiseKey,
+            existingSigningPublicKey: signingKey,
+            announcedSigningPublicKey: signingKey
+        )
+
+        #expect(decision == .verified)
+    }
+
    @Test
    func responsePolicyConnectsOnlyForDirectNewOrReconnectedPeers() {
        let directNew = BLEAnnounceResponsePolicy.plan(
@@ -6,12 +6,12 @@ import Testing
@Suite("BLE peer registry tests")
 struct BLEPeerRegistryTests {
    @Test("upserted announces track new, reconnect, and rename transitions")
-    func upsertVerifiedAnnounceTracksTransitions() {
+    func upsertVerifiedAnnounceTracksTransitions() throws {
        var registry = BLEPeerRegistry()
        let peerID = PeerID(str: "1122334455667788")
        let firstSeen = Date(timeIntervalSince1970: 100)

-        let first = registry.upsertVerifiedAnnounce(
+        let firstResult = registry.upsertVerifiedAnnounce(
            peerID: peerID,
            nickname: "alice",
            noisePublicKey: Data([1, 2, 3]),
@@ -19,6 +19,7 @@ struct BLEPeerRegistryTests {
            isConnected: true,
            now: firstSeen
        )
+        let first = try #require(firstResult)

        #expect(first.isNewPeer)
        #expect(!first.wasDisconnected)
@@ -27,7 +28,7 @@ struct BLEPeerRegistryTests {
        #expect(registry.nickname(for: peerID, connectedOnly: true) == "alice")

        registry.markDisconnected(peerID)
-        let reconnect = registry.upsertVerifiedAnnounce(
+        let reconnectResult = registry.upsertVerifiedAnnounce(
            peerID: peerID,
            nickname: "alice-renamed",
            noisePublicKey: Data([1, 2, 3]),
@@ -35,6 +36,7 @@ struct BLEPeerRegistryTests {
            isConnected: true,
            now: firstSeen.addingTimeInterval(1)
        )
+        let reconnect = try #require(reconnectResult)

        #expect(!reconnect.isNewPeer)
        #expect(reconnect.wasDisconnected)
@@ -42,6 +44,85 @@ struct BLEPeerRegistryTests {
        #expect(registry.info(for: peerID)?.nickname == "alice-renamed")
    }

+    @Test("pinned signing key cannot be silently replaced by a later announce")
+    func upsertVerifiedAnnounceRefusesToReplacePinnedSigningKey() throws {
+        var registry = BLEPeerRegistry()
+        let peerID = PeerID(str: "1122334455667788")
+        let noiseKey = Data(repeating: 0x11, count: 32)
+        let victimSigningKey = Data(repeating: 0x42, count: 32)
+        let attackerSigningKey = Data(repeating: 0x66, count: 32)
+        let firstSeen = Date(timeIntervalSince1970: 100)
+
+        let pinResult = registry.upsertVerifiedAnnounce(
+            peerID: peerID,
+            nickname: "victim",
+            noisePublicKey: noiseKey,
+            signingPublicKey: victimSigningKey,
+            isConnected: true,
+            now: firstSeen
+        )
+        #expect(pinResult != nil)
+
+        // Attacker replays the victim's noiseKey/peerID with their own
+        // signing key and nickname; the upsert must be refused wholesale.
+        let attack = registry.upsertVerifiedAnnounce(
+            peerID: peerID,
+            nickname: "attacker",
+            noisePublicKey: noiseKey,
+            signingPublicKey: attackerSigningKey,
+            isConnected: true,
+            now: firstSeen.addingTimeInterval(1)
+        )
+
+        #expect(attack == nil)
+        let info = try #require(registry.info(for: peerID))
+        #expect(info.nickname == "victim")
+        #expect(info.signingPublicKey == victimSigningKey)
+
+        // A legitimate re-announce with the pinned key is still accepted.
+        let legit = registry.upsertVerifiedAnnounce(
+            peerID: peerID,
+            nickname: "victim-renamed",
+            noisePublicKey: noiseKey,
+            signingPublicKey: victimSigningKey,
+            isConnected: true,
+            now: firstSeen.addingTimeInterval(2)
+        )
+        #expect(legit != nil)
+        #expect(registry.info(for: peerID)?.nickname == "victim-renamed")
+    }
+
+    @Test("announce without a signing key keeps the pinned key")
+    func upsertVerifiedAnnounceKeepsPinnedSigningKeyWhenAnnounceOmitsIt() throws {
+        var registry = BLEPeerRegistry()
+        let peerID = PeerID(str: "1122334455667788")
+        let noiseKey = Data(repeating: 0x11, count: 32)
+        let signingKey = Data(repeating: 0x42, count: 32)
+        let firstSeen = Date(timeIntervalSince1970: 100)
+
+        let initialResult = registry.upsertVerifiedAnnounce(
+            peerID: peerID,
+            nickname: "alice",
+            noisePublicKey: noiseKey,
+            signingPublicKey: signingKey,
+            isConnected: true,
+            now: firstSeen
+        )
+        #expect(initialResult != nil)
+
+        let update = registry.upsertVerifiedAnnounce(
+            peerID: peerID,
+            nickname: "alice",
+            noisePublicKey: noiseKey,
+            signingPublicKey: nil,
+            isConnected: true,
+            now: firstSeen.addingTimeInterval(1)
+        )
+
+        #expect(update != nil)
+        #expect(registry.info(for: peerID)?.signingPublicKey == signingKey)
+    }
+
    @Test("reachability keeps recent verified offline peers only when mesh is attached")
    func reachabilityRequiresMeshAttachmentForOfflinePeers() {
        let offlinePeer = PeerID(str: "1122334455667788")
@@ -79,6 +79,100 @@ final class SecureIdentityStateManagerTests: XCTestCase {
        XCTAssertEqual(matches.first?.signingPublicKey, signingPublicKey)
    }

+    func test_upsertCryptographicIdentity_refusesToReplacePinnedSigningKey() async {
+        let manager = SecureIdentityStateManager(MockKeychain())
+        let noisePublicKey = Data(repeating: 0x11, count: 32)
+        let fingerprint = noisePublicKey.sha256Fingerprint()
+        let peerID = PeerID(publicKey: noisePublicKey)
+        let victimSigningKey = Data(repeating: 0x22, count: 32)
+        let attackerSigningKey = Data(repeating: 0x66, count: 32)
+
+        manager.upsertCryptographicIdentity(
+            fingerprint: fingerprint,
+            noisePublicKey: noisePublicKey,
+            signingPublicKey: victimSigningKey,
+            claimedNickname: "victim"
+        )
+        let pinned = await waitUntil {
+            manager.getCryptoIdentitiesByPeerIDPrefix(peerID).first?.signingPublicKey == victimSigningKey
+        }
+        XCTAssertTrue(pinned)
+
+        // Attacker upsert with a different signing key must be refused in
+        // full — signing key AND claimed nickname stay the victim's.
+        manager.upsertCryptographicIdentity(
+            fingerprint: fingerprint,
+            noisePublicKey: noisePublicKey,
+            signingPublicKey: attackerSigningKey,
+            claimedNickname: "attacker"
+        )
+
+        // Synchronous reads fence the manager's pending barrier writes.
+        XCTAssertEqual(
+            manager.getCryptoIdentitiesByPeerIDPrefix(peerID).first?.signingPublicKey,
+            victimSigningKey
+        )
+        XCTAssertEqual(manager.getSocialIdentity(for: fingerprint)?.claimedNickname, "victim")
+
+        // The legitimate peer (same signing key) can still update.
+        manager.upsertCryptographicIdentity(
+            fingerprint: fingerprint,
+            noisePublicKey: noisePublicKey,
+            signingPublicKey: victimSigningKey,
+            claimedNickname: "victim-renamed"
+        )
+        let renamed = await waitUntil {
+            manager.getSocialIdentity(for: fingerprint)?.claimedNickname == "victim-renamed"
+        }
+        XCTAssertTrue(renamed)
+        XCTAssertEqual(
+            manager.getCryptoIdentitiesByPeerIDPrefix(peerID).first?.signingPublicKey,
+            victimSigningKey
+        )
+    }
+
+    func test_cryptographicIdentity_persistsAcrossReinitAndKeepsSigningKeyPin() async {
+        let keychain = MockKeychain()
+        let manager = SecureIdentityStateManager(keychain)
+        let noisePublicKey = Data(repeating: 0x13, count: 32)
+        let fingerprint = noisePublicKey.sha256Fingerprint()
+        let peerID = PeerID(publicKey: noisePublicKey)
+        let victimSigningKey = Data(repeating: 0x24, count: 32)
+        let attackerSigningKey = Data(repeating: 0x77, count: 32)
+
+        manager.upsertCryptographicIdentity(
+            fingerprint: fingerprint,
+            noisePublicKey: noisePublicKey,
+            signingPublicKey: victimSigningKey,
+            claimedNickname: "victim"
+        )
+        let pinned = await waitUntil {
+            manager.getCryptoIdentitiesByPeerIDPrefix(peerID).first?.signingPublicKey == victimSigningKey
+        }
+        XCTAssertTrue(pinned)
+        manager.forceSave()
+
+        // Simulated app restart: the pin must survive and still refuse a
+        // different signing key.
+        let reloaded = SecureIdentityStateManager(keychain)
+        XCTAssertEqual(
+            reloaded.getCryptoIdentitiesByPeerIDPrefix(peerID).first?.signingPublicKey,
+            victimSigningKey
+        )
+
+        reloaded.upsertCryptographicIdentity(
+            fingerprint: fingerprint,
+            noisePublicKey: noisePublicKey,
+            signingPublicKey: attackerSigningKey,
+            claimedNickname: "attacker"
+        )
+        XCTAssertEqual(
+            reloaded.getCryptoIdentitiesByPeerIDPrefix(peerID).first?.signingPublicKey,
+            victimSigningKey
+        )
+        XCTAssertEqual(reloaded.getSocialIdentity(for: fingerprint)?.claimedNickname, "victim")
+    }
+
    func test_setBlocked_clearsFavoriteState() async {
        let manager = SecureIdentityStateManager(MockKeychain())
        let fingerprint = String(repeating: "ab", count: 32)