Extract Noise into a dedicated module

localPackages/Noise/Package.swift

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+// swift-tools-version: 5.9
+
+import PackageDescription
+
+let package = Package(
+    name: "Noise",
+    platforms: [
+        .iOS(.v16),
+        .macOS(.v13)
+    ],
+    products: [
+        .library(
+            name: "Noise",
+            targets: ["Noise"]
+        ),
+    ],
+    dependencies: [
+        .package(path: "../BitLogger"),
+        .package(path: "../BitFoundation"),
+    ],
+    targets: [
+        .target(
+            name: "Noise",
+            dependencies: [
+                .product(name: "BitLogger", package: "BitLogger"),
+                .product(name: "BitFoundation", package: "BitFoundation"),
+            ],
+            path: "Sources"
+        ),
+        .testTarget(
+            name: "NoiseTests",
+            dependencies: ["Noise"],
+            resources: [
+                .process("NoiseTestVectors.json")
+            ]
+        ),
+    ]
+)

localPackages/Noise/Sources/Noise/NoiseEncryptionService.swift

@@ -0,0 +1,772 @@
+//
+// NoiseEncryptionService.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+///
+/// # NoiseEncryptionService
+///
+/// High-level encryption service that manages Noise Protocol sessions for secure
+/// peer-to-peer communication in BitChat. Acts as the bridge between the transport
+/// layer (BLEService) and the cryptographic layer (NoiseProtocol).
+///
+/// ## Overview
+/// This service provides a simplified API for establishing and managing encrypted
+/// channels between peers. It handles:
+/// - Static identity key management
+/// - Session lifecycle (creation, maintenance, teardown)
+/// - Message encryption/decryption
+/// - Peer authentication and fingerprint tracking
+/// - Automatic rekeying for forward secrecy
+///
+/// ## Architecture
+/// The service operates at multiple levels:
+/// 1. **Identity Management**: Persistent Curve25519 keys stored in Keychain
+/// 2. **Session Management**: Per-peer Noise sessions with state tracking
+/// 3. **Message Processing**: Encryption/decryption with proper framing
+/// 4. **Security Features**: Rate limiting, fingerprint verification
+///
+/// ## Key Features
+///
+/// ### Identity Keys
+/// - Static Curve25519 key pair for Noise XX pattern
+/// - Ed25519 signing key pair for additional authentication
+/// - Keys persisted securely in iOS/macOS Keychain
+/// - Fingerprints derived from SHA256 of public keys
+///
+/// ### Session Management
+/// - Lazy session creation (on-demand when sending messages)
+/// - Automatic session recovery after disconnections
+/// - Configurable rekey intervals for forward secrecy
+/// - Graceful handling of simultaneous handshakes
+///
+/// ### Security Properties
+/// - Forward secrecy via ephemeral keys in handshakes
+/// - Mutual authentication via static key exchange
+/// - Protection against replay attacks
+/// - Rate limiting to prevent DoS attacks
+///
+/// ## Encryption Flow
+/// ```
+/// 1. Message arrives for encryption
+/// 2. Check if session exists for peer
+/// 3. If not, initiate Noise handshake
+/// 4. Once established, encrypt message
+/// 5. Add message type header for protocol handling
+/// 6. Return encrypted payload for transmission
+/// ```
+///
+/// ## Integration Points
+/// - **BLEService**: Calls this service for all private messages
+/// - **ChatViewModel**: Monitors encryption status for UI indicators
+/// - **KeychainManager**: Secure storage for identity keys
+///
+/// ## Thread Safety
+/// - Concurrent read access via reader-writer queue
+/// - Session operations protected by per-peer queues
+/// - Atomic updates for critical state changes
+///
+/// ## Error Handling
+/// - Graceful fallback for encryption failures
+/// - Clear error messages for debugging
+/// - Automatic retry with exponential backoff
+/// - User notification for critical failures
+///
+/// ## Performance Considerations
+/// - Sessions cached in memory for fast access
+/// - Minimal allocations in hot paths
+/// - Efficient binary message format
+/// - Background queue for CPU-intensive operations
+///
+
+import BitLogger
+import BitFoundation
+import Foundation
+import CryptoKit
+
+// MARK: - Encryption Status
+
+/// Represents the current encryption status of a peer connection.
+/// Used for UI indicators and decision-making about message handling.
+enum EncryptionStatus: Equatable {
+    case none                // Failed or incompatible
+    case noHandshake        // No handshake attempted yet
+    case noiseHandshaking   // Currently establishing
+    case noiseSecured       // Established but not verified
+    case noiseVerified      // Established and verified
+    
+    var icon: String? {  // Made optional to hide icon when no handshake
+        switch self {
+        case .none:
+            return "lock.slash"  // Failed handshake
+        case .noHandshake:
+            return nil  // No icon when no handshake attempted
+        case .noiseHandshaking:
+            return "lock.rotation"
+        case .noiseSecured:
+            return "lock.fill"  // Changed from "lock" to "lock.fill" for filled lock
+        case .noiseVerified:
+            return "checkmark.seal.fill"  // Verified badge
+        }
+    }
+    
+    var description: String {
+        switch self {
+        case .none:
+            return String(localized: "encryption.status.failed", comment: "Status text when encryption failed")
+        case .noHandshake:
+            return String(localized: "encryption.status.not_encrypted", comment: "Status text when no encryption handshake happened")
+        case .noiseHandshaking:
+            return String(localized: "encryption.status.establishing", comment: "Status text when encryption is being established")
+        case .noiseSecured:
+            return String(localized: "encryption.status.secured", comment: "Status text when encryption is secured but not verified")
+        case .noiseVerified:
+            return String(localized: "encryption.status.verified", comment: "Status text when encryption is verified")
+        }
+    }
+
+    var accessibilityDescription: String {
+        switch self {
+        case .none:
+            return String(localized: "encryption.accessibility.failed", comment: "Accessibility text when encryption failed")
+        case .noHandshake:
+            return String(localized: "encryption.accessibility.not_encrypted", comment: "Accessibility text when encryption is not established")
+        case .noiseHandshaking:
+            return String(localized: "encryption.accessibility.establishing", comment: "Accessibility text when encryption is being established")
+        case .noiseSecured:
+            return String(localized: "encryption.accessibility.secured", comment: "Accessibility text when encryption is secured")
+        case .noiseVerified:
+            return String(localized: "encryption.accessibility.verified", comment: "Accessibility text when encryption is verified")
+        }
+    }
+}
+
+// MARK: - Noise Encryption Service
+
+/// Manages end-to-end encryption for BitChat using the Noise Protocol Framework.
+/// Provides a high-level API for establishing secure channels between peers,
+/// handling all cryptographic operations transparently.
+/// - Important: This service maintains the device's cryptographic identity
+final class NoiseEncryptionService {
+    // Static identity key (persistent across sessions)
+    private let staticIdentityKey: Curve25519.KeyAgreement.PrivateKey
+    public let staticIdentityPublicKey: Curve25519.KeyAgreement.PublicKey
+    
+    // Ed25519 signing key (persistent across sessions)
+    private let signingKey: Curve25519.Signing.PrivateKey
+    public let signingPublicKey: Curve25519.Signing.PublicKey
+    
+    // Session manager
+    private let sessionManager: NoiseSessionManager
+    
+    // Peer fingerprints (SHA256 hash of static public key)
+    private var peerFingerprints: [PeerID: String] = [:]
+    private var fingerprintToPeerID: [String: PeerID] = [:]
+    
+    // Thread safety
+    private let serviceQueue = DispatchQueue(label: "chat.bitchat.noise.service", attributes: .concurrent)
+    
+    // Security components
+    private let rateLimiter = NoiseRateLimiter()
+    private let keychain: KeychainManagerProtocol
+    
+    // Session maintenance
+    private var rekeyTimer: Timer?
+    private let rekeyCheckInterval: TimeInterval = 60.0 // Check every minute
+    
+    // Callbacks
+    private var onPeerAuthenticatedHandlers: [((PeerID, String) -> Void)] = [] // Array of handlers for peer authentication
+    var onHandshakeRequired: ((PeerID) -> Void)? // peerID needs handshake
+    
+    // Add a handler for peer authentication
+    func addOnPeerAuthenticatedHandler(_ handler: @escaping (PeerID, String) -> Void) {
+        serviceQueue.async(flags: .barrier) { [weak self] in
+            self?.onPeerAuthenticatedHandlers.append(handler)
+        }
+    }
+    
+    // Legacy support - setting this will add to the handlers array
+    var onPeerAuthenticated: ((PeerID, String) -> Void)? {
+        get { nil } // Always return nil for backward compatibility
+        set {
+            if let handler = newValue {
+                addOnPeerAuthenticatedHandler(handler)
+            }
+        }
+    }
+    
+    init(keychain: KeychainManagerProtocol) {
+        self.keychain = keychain
+
+        // BCH-01-009: Load or create static identity key with proper error handling
+        let loadedKey: Curve25519.KeyAgreement.PrivateKey
+
+        // Try to load from keychain with proper error classification
+        let noiseKeyResult = keychain.getIdentityKeyWithResult(forKey: "noiseStaticKey")
+
+        switch noiseKeyResult {
+        case .success(let identityData):
+            if let key = try? Curve25519.KeyAgreement.PrivateKey(rawRepresentation: identityData) {
+                loadedKey = key
+                SecureLogger.logKeyOperation(.load, keyType: "noiseStaticKey", success: true)
+            } else {
+                // Data corrupted, regenerate
+                SecureLogger.warning("Noise static key data corrupted, regenerating", category: .keychain)
+                loadedKey = Self.generateAndSaveNoiseKey(keychain: keychain)
+            }
+
+        case .itemNotFound:
+            // Expected case: no key exists yet, create new one
+            loadedKey = Self.generateAndSaveNoiseKey(keychain: keychain)
+
+        case .accessDenied:
+            // Critical error - log but proceed with ephemeral key (will be lost on restart)
+            SecureLogger.error(NSError(domain: "Keychain", code: -1),
+                               context: "Keychain access denied - using ephemeral identity", category: .keychain)
+            loadedKey = Curve25519.KeyAgreement.PrivateKey()
+
+        case .deviceLocked, .authenticationFailed:
+            // Recoverable error - use ephemeral key and warn
+            SecureLogger.warning("Device locked or auth failed - using ephemeral identity until unlocked", category: .keychain)
+            loadedKey = Curve25519.KeyAgreement.PrivateKey()
+
+        case .otherError(let status):
+            // Unexpected error - log and use ephemeral key
+            SecureLogger.error(NSError(domain: "Keychain", code: Int(status)),
+                               context: "Unexpected keychain error - using ephemeral identity", category: .keychain)
+            loadedKey = Curve25519.KeyAgreement.PrivateKey()
+        }
+
+        // Now assign the final value
+        self.staticIdentityKey = loadedKey
+        self.staticIdentityPublicKey = staticIdentityKey.publicKey
+
+        // BCH-01-009: Load or create signing key pair with proper error handling
+        let loadedSigningKey: Curve25519.Signing.PrivateKey
+
+        let signingKeyResult = keychain.getIdentityKeyWithResult(forKey: "ed25519SigningKey")
+
+        switch signingKeyResult {
+        case .success(let signingData):
+            if let key = try? Curve25519.Signing.PrivateKey(rawRepresentation: signingData) {
+                loadedSigningKey = key
+                SecureLogger.logKeyOperation(.load, keyType: "ed25519SigningKey", success: true)
+            } else {
+                // Data corrupted, regenerate
+                SecureLogger.warning("Ed25519 signing key data corrupted, regenerating", category: .keychain)
+                loadedSigningKey = Self.generateAndSaveSigningKey(keychain: keychain)
+            }
+
+        case .itemNotFound:
+            // Expected case: no key exists yet, create new one
+            loadedSigningKey = Self.generateAndSaveSigningKey(keychain: keychain)
+
+        case .accessDenied:
+            // Critical error - log but proceed with ephemeral key
+            SecureLogger.error(NSError(domain: "Keychain", code: -1),
+                               context: "Keychain access denied - using ephemeral signing key", category: .keychain)
+            loadedSigningKey = Curve25519.Signing.PrivateKey()
+
+        case .deviceLocked, .authenticationFailed:
+            // Recoverable error - use ephemeral key and warn
+            SecureLogger.warning("Device locked or auth failed - using ephemeral signing key until unlocked", category: .keychain)
+            loadedSigningKey = Curve25519.Signing.PrivateKey()
+
+        case .otherError(let status):
+            // Unexpected error - log and use ephemeral key
+            SecureLogger.error(NSError(domain: "Keychain", code: Int(status)),
+                               context: "Unexpected keychain error - using ephemeral signing key", category: .keychain)
+            loadedSigningKey = Curve25519.Signing.PrivateKey()
+        }
+
+        // Now assign the signing keys
+        self.signingKey = loadedSigningKey
+        self.signingPublicKey = signingKey.publicKey
+
+        // Initialize session manager
+        self.sessionManager = NoiseSessionManager(localStaticKey: staticIdentityKey, keychain: keychain)
+
+        // Set up session callbacks
+        sessionManager.onSessionEstablished = { [weak self] peerID, remoteStaticKey in
+            self?.handleSessionEstablished(peerID: peerID, remoteStaticKey: remoteStaticKey)
+        }
+
+        // Start session maintenance timer
+        startRekeyTimer()
+    }
+
+    // MARK: - BCH-01-009: Key Generation Helpers with Save Verification
+
+    /// Generate and save a new Noise static key, verifying the save succeeds
+    private static func generateAndSaveNoiseKey(keychain: KeychainManagerProtocol) -> Curve25519.KeyAgreement.PrivateKey {
+        let newKey = Curve25519.KeyAgreement.PrivateKey()
+        let keyData = newKey.rawRepresentation
+
+        // Save to keychain and verify success
+        let saveResult = keychain.saveIdentityKeyWithResult(keyData, forKey: "noiseStaticKey")
+
+        switch saveResult {
+        case .success:
+            SecureLogger.logKeyOperation(.create, keyType: "noiseStaticKey", success: true)
+        case .duplicateItem:
+            // This shouldn't happen since we just tried to load, but handle it
+            SecureLogger.warning("Noise key already exists (race condition?)", category: .keychain)
+        default:
+            // Save failed - log but continue with the key (it will be ephemeral)
+            SecureLogger.error(NSError(domain: "Keychain", code: -1),
+                               context: "Failed to persist noise static key - identity will be lost on restart",
+                               category: .keychain)
+        }
+
+        return newKey
+    }
+
+    /// Generate and save a new Ed25519 signing key, verifying the save succeeds
+    private static func generateAndSaveSigningKey(keychain: KeychainManagerProtocol) -> Curve25519.Signing.PrivateKey {
+        let newKey = Curve25519.Signing.PrivateKey()
+        let keyData = newKey.rawRepresentation
+
+        // Save to keychain and verify success
+        let saveResult = keychain.saveIdentityKeyWithResult(keyData, forKey: "ed25519SigningKey")
+
+        switch saveResult {
+        case .success:
+            SecureLogger.logKeyOperation(.create, keyType: "ed25519SigningKey", success: true)
+        case .duplicateItem:
+            // This shouldn't happen since we just tried to load, but handle it
+            SecureLogger.warning("Signing key already exists (race condition?)", category: .keychain)
+        default:
+            // Save failed - log but continue with the key (it will be ephemeral)
+            SecureLogger.error(NSError(domain: "Keychain", code: -1),
+                               context: "Failed to persist signing key - identity will be lost on restart",
+                               category: .keychain)
+        }
+
+        return newKey
+    }
+    
+    // MARK: - Public Interface
+    
+    /// Get our static public key for sharing
+    func getStaticPublicKeyData() -> Data {
+        return staticIdentityPublicKey.rawRepresentation
+    }
+    
+    /// Get our signing public key for sharing
+    func getSigningPublicKeyData() -> Data {
+        return signingPublicKey.rawRepresentation
+    }
+    
+    /// Get our identity fingerprint
+    func getIdentityFingerprint() -> String {
+        staticIdentityPublicKey.rawRepresentation.sha256Fingerprint()
+    }
+    
+    /// Get peer's public key data
+    func getPeerPublicKeyData(_ peerID: PeerID) -> Data? {
+        return sessionManager.getRemoteStaticKey(for: peerID)?.rawRepresentation
+    }
+    
+    /// Clear persistent identity (for panic mode)
+    func clearPersistentIdentity() {
+        // Clear from keychain
+        let deletedStatic = keychain.deleteIdentityKey(forKey: "noiseStaticKey")
+        let deletedSigning = keychain.deleteIdentityKey(forKey: "ed25519SigningKey")
+        SecureLogger.logKeyOperation(.delete, keyType: "identity keys", success: deletedStatic && deletedSigning)
+        SecureLogger.warning("Panic mode activated - identity cleared", category: .security)
+        // Stop rekey timer
+        stopRekeyTimer()
+    }
+    
+    /// Sign data with our Ed25519 signing key
+    func signData(_ data: Data) -> Data? {
+        do {
+            let signature = try signingKey.signature(for: data)
+            return signature
+        } catch {
+            SecureLogger.error(error, context: "Failed to sign data")
+            return nil
+        }
+    }
+    
+    /// Verify signature with a peer's Ed25519 public key
+    func verifySignature(_ signature: Data, for data: Data, publicKey: Data) -> Bool {
+        do {
+            let signingPublicKey = try Curve25519.Signing.PublicKey(rawRepresentation: publicKey)
+            return signingPublicKey.isValidSignature(signature, for: data)
+        } catch {
+            SecureLogger.error(error, context: "Failed to verify signature")
+            return false
+        }
+    }
+
+    // MARK: - Announce Signature Helpers
+
+    /// Build the canonical announce binding message bytes and sign with our Ed25519 key
+    /// - Parameters:
+    ///   - peerID: 8-byte routing ID (as in packet header)
+    ///   - noiseKey: 32-byte Curve25519.KeyAgreement public key
+    ///   - ed25519Key: 32-byte Ed25519 public key (self)
+    ///   - nickname: UTF-8 nickname (<=255 bytes)
+    ///   - timestampMs: UInt64 milliseconds since epoch
+    /// - Returns: Ed25519 signature over the canonical bytes, or nil on failure
+    func buildAnnounceSignature(peerID: Data, noiseKey: Data, ed25519Key: Data, nickname: String, timestampMs: UInt64) -> Data? {
+        let message = canonicalAnnounceBytes(peerID: peerID, noiseKey: noiseKey, ed25519Key: ed25519Key, nickname: nickname, timestampMs: timestampMs)
+        return signData(message)
+    }
+
+    /// Verify an announce signature
+    func verifyAnnounceSignature(signature: Data, peerID: Data, noiseKey: Data, ed25519Key: Data, nickname: String, timestampMs: UInt64, publicKey: Data) -> Bool {
+        let message = canonicalAnnounceBytes(peerID: peerID, noiseKey: noiseKey, ed25519Key: ed25519Key, nickname: nickname, timestampMs: timestampMs)
+        return verifySignature(signature, for: message, publicKey: publicKey)
+    }
+
+    /// Build canonical bytes for announce signing.
+    private func canonicalAnnounceBytes(peerID: Data, noiseKey: Data, ed25519Key: Data, nickname: String, timestampMs: UInt64) -> Data {
+        var out = Data()
+        // context
+        let context = "bitchat-announce-v1".data(using: .utf8) ?? Data()
+        out.append(UInt8(min(context.count, 255)))
+        out.append(context.prefix(255))
+        // peerID (expect 8 bytes; pad/truncate to 8 for canonicalization)
+        let peerID8 = peerID.prefix(8)
+        out.append(peerID8)
+        if peerID8.count < 8 { out.append(Data(repeating: 0, count: 8 - peerID8.count)) }
+        // noise static key (expect 32)
+        let noise32 = noiseKey.prefix(32)
+        out.append(noise32)
+        if noise32.count < 32 { out.append(Data(repeating: 0, count: 32 - noise32.count)) }
+        // ed25519 public key (expect 32)
+        let ed32 = ed25519Key.prefix(32)
+        out.append(ed32)
+        if ed32.count < 32 { out.append(Data(repeating: 0, count: 32 - ed32.count)) }
+        // nickname length + bytes
+        let nickData = nickname.data(using: .utf8) ?? Data()
+        out.append(UInt8(min(nickData.count, 255)))
+        out.append(nickData.prefix(255))
+        // timestamp
+        var ts = timestampMs.bigEndian
+        withUnsafeBytes(of: &ts) { raw in out.append(contentsOf: raw) }
+        return out
+    }
+    
+    // MARK: - Packet Signing/Verification
+    
+    /// Sign a BitchatPacket using the noise private key
+    func signPacket(_ packet: BitchatPacket) -> BitchatPacket? {
+        // Create canonical packet bytes for signing
+        guard let packetData = packet.toBinaryDataForSigning() else {
+            return nil
+        }
+        
+        // Sign with the noise private key (converted to Ed25519 for signing)
+        guard let signature = signData(packetData) else {
+            return nil
+        }
+        
+        // Return new packet with signature
+        var signedPacket = packet
+        signedPacket.signature = signature
+        return signedPacket
+    }
+    
+    /// Verify a BitchatPacket signature using the provided public key
+    func verifyPacketSignature(_ packet: BitchatPacket, publicKey: Data) -> Bool {
+        guard let signature = packet.signature else {
+            return false
+        }
+        
+        // Create canonical packet bytes for verification (without signature)
+        
+        guard let packetData = packet.toBinaryDataForSigning() else {
+            return false
+        }
+        
+        // For noise public keys, we need to derive the Ed25519 key for verification
+        // This assumes the noise key can be used for Ed25519 signing
+        return verifySignature(signature, for: packetData, publicKey: publicKey)
+    }
+
+    
+    // MARK: - Handshake Management
+    
+    /// Initiate a Noise handshake with a peer
+    func initiateHandshake(with peerID: PeerID) throws -> Data {
+        
+        // Validate peer ID
+        guard peerID.isValid else {
+            SecureLogger.warning(.authenticationFailed(peerID: peerID.id))
+            throw NoiseSecurityError.invalidPeerID
+        }
+        
+        // Check rate limit
+        guard rateLimiter.allowHandshake(from: peerID) else {
+            SecureLogger.warning(.authenticationFailed(peerID: "Rate limited: \(peerID)"))
+            throw NoiseSecurityError.rateLimitExceeded
+        }
+        
+        SecureLogger.info(.handshakeStarted(peerID: peerID.id))
+        
+        // Return raw handshake data without wrapper
+        // The Noise protocol handles its own message format
+        let handshakeData = try sessionManager.initiateHandshake(with: peerID)
+        return handshakeData
+    }
+    
+    /// Process an incoming handshake message
+    func processHandshakeMessage(from peerID: PeerID, message: Data) throws -> Data? {
+        
+        // Validate peer ID
+        guard peerID.isValid else {
+            SecureLogger.warning(.authenticationFailed(peerID: peerID.id))
+            throw NoiseSecurityError.invalidPeerID
+        }
+        
+        // Validate message size
+        guard NoiseSecurityValidator.validateHandshakeMessageSize(message) else {
+            SecureLogger.warning(.handshakeFailed(peerID: peerID.id, error: "Message too large"))
+            throw NoiseSecurityError.messageTooLarge
+        }
+        
+        // Check rate limit
+        guard rateLimiter.allowHandshake(from: peerID) else {
+            SecureLogger.warning(.authenticationFailed(peerID: "Rate limited: \(peerID)"))
+            throw NoiseSecurityError.rateLimitExceeded
+        }
+        
+        // For handshakes, we process the raw data directly without NoiseMessage wrapper
+        // The Noise protocol handles its own message format
+        let responsePayload = try sessionManager.handleIncomingHandshake(from: peerID, message: message)
+        
+        
+        // Return raw response without wrapper
+        return responsePayload
+    }
+    
+    /// Check if we have an established session with a peer
+    func hasEstablishedSession(with peerID: PeerID) -> Bool {
+        return sessionManager.getSession(for: peerID)?.isEstablished() ?? false
+    }
+    
+    /// Check if we have a session (established or handshaking) with a peer
+    func hasSession(with peerID: PeerID) -> Bool {
+        return sessionManager.getSession(for: peerID) != nil
+    }
+    
+    // MARK: - Encryption/Decryption
+    
+    /// Encrypt data for a specific peer
+    func encrypt(_ data: Data, for peerID: PeerID) throws -> Data {
+        // Validate message size
+        guard NoiseSecurityValidator.validateMessageSize(data) else {
+            throw NoiseSecurityError.messageTooLarge
+        }
+        
+        // Check rate limit
+        guard rateLimiter.allowMessage(from: peerID) else {
+            throw NoiseSecurityError.rateLimitExceeded
+        }
+        
+        // Check if we have an established session
+        guard hasEstablishedSession(with: peerID) else {
+            // Signal that handshake is needed
+            onHandshakeRequired?(peerID)
+            throw NoiseEncryptionError.handshakeRequired
+        }
+        
+        return try sessionManager.encrypt(data, for: peerID)
+    }
+    
+    /// Decrypt data from a specific peer
+    func decrypt(_ data: Data, from peerID: PeerID) throws -> Data {
+        // Validate message size
+        guard NoiseSecurityValidator.validateMessageSize(data) else {
+            throw NoiseSecurityError.messageTooLarge
+        }
+        
+        // Check rate limit
+        guard rateLimiter.allowMessage(from: peerID) else {
+            throw NoiseSecurityError.rateLimitExceeded
+        }
+        
+        // Check if we have an established session
+        guard hasEstablishedSession(with: peerID) else {
+            throw NoiseEncryptionError.sessionNotEstablished
+        }
+        
+        return try sessionManager.decrypt(data, from: peerID)
+    }
+    
+    // MARK: - Peer Management
+    
+    /// Get fingerprint for a peer
+    func getPeerFingerprint(_ peerID: PeerID) -> String? {
+        return serviceQueue.sync {
+            return peerFingerprints[peerID]
+        }
+    }
+
+    func clearEphemeralStateForPanic() {
+        sessionManager.removeAllSessions()
+        serviceQueue.sync(flags: .barrier) {
+            peerFingerprints.removeAll()
+            fingerprintToPeerID.removeAll()
+        }
+        rateLimiter.resetAll()
+    }
+
+    /// Clear session for a specific peer (e.g., on decryption failure to allow re-handshake)
+    func clearSession(for peerID: PeerID) {
+        sessionManager.removeSession(for: peerID)
+        serviceQueue.sync(flags: .barrier) {
+            if let fingerprint = peerFingerprints.removeValue(forKey: peerID) {
+                fingerprintToPeerID.removeValue(forKey: fingerprint)
+            }
+        }
+        SecureLogger.debug("🔓 Cleared Noise session for \(peerID)", category: .session)
+    }
+    
+    // MARK: - Private Helpers
+    
+    private func handleSessionEstablished(peerID: PeerID, remoteStaticKey: Curve25519.KeyAgreement.PublicKey) {
+        // Calculate fingerprint
+        let fingerprint = remoteStaticKey.rawRepresentation.sha256Fingerprint()
+        
+        // Store fingerprint mapping
+        serviceQueue.sync(flags: .barrier) {
+            peerFingerprints[peerID] = fingerprint
+            fingerprintToPeerID[fingerprint] = peerID
+        }
+        
+        // Log security event
+        SecureLogger.info(.handshakeCompleted(peerID: peerID.id))
+        
+        // Notify all handlers about authentication
+        serviceQueue.async { [weak self] in
+            self?.onPeerAuthenticatedHandlers.forEach { handler in
+                handler(peerID, fingerprint)
+            }
+        }
+    }
+        
+    // MARK: - Session Maintenance
+    
+    private func startRekeyTimer() {
+        rekeyTimer = Timer.scheduledTimer(withTimeInterval: rekeyCheckInterval, repeats: true) { [weak self] _ in
+            self?.checkSessionsForRekey()
+        }
+    }
+    
+    private func stopRekeyTimer() {
+        rekeyTimer?.invalidate()
+        rekeyTimer = nil
+    }
+    
+    private func checkSessionsForRekey() {
+        let sessionsNeedingRekey = sessionManager.getSessionsNeedingRekey()
+        
+        for (peerID, needsRekey) in sessionsNeedingRekey where needsRekey {
+            
+            // Attempt to rekey the session
+            do {
+                try sessionManager.initiateRekey(for: peerID)
+                SecureLogger.debug("Key rotation initiated for peer: \(peerID)", category: .security)
+                
+                // Signal that handshake is needed
+                onHandshakeRequired?(peerID)
+            } catch {
+                SecureLogger.error(error, context: "Failed to initiate rekey for peer: \(peerID)", category: .session)
+            }
+        }
+    }
+    
+    deinit {
+        stopRekeyTimer()
+    }
+}
+
+// MARK: - Protocol Message Types for Noise
+
+/// Message types for the Noise encryption protocol layer.
+/// These types wrap the underlying BitChat protocol messages with encryption metadata.
+enum NoiseMessageType: UInt8 {
+    case handshakeInitiation = 0x10
+    case handshakeResponse = 0x11
+    case handshakeFinal = 0x12
+    case encryptedMessage = 0x13
+    case sessionRenegotiation = 0x14
+}
+
+// MARK: - Noise Message Wrapper
+
+/// Container for encrypted messages in the Noise protocol.
+/// Provides versioning and type information for proper message handling.
+/// The actual message content is encrypted in the payload field.
+struct NoiseMessage: Codable {
+    let type: UInt8
+    let sessionID: String  // Random ID for this handshake session
+    let payload: Data
+    
+    init(type: NoiseMessageType, sessionID: String, payload: Data) {
+        self.type = type.rawValue
+        self.sessionID = sessionID
+        self.payload = payload
+    }
+    
+    func encode() -> Data? {
+        do {
+            let encoded = try JSONEncoder().encode(self)
+            return encoded
+        } catch {
+            return nil
+        }
+    }
+    
+    static func decode(from data: Data) -> NoiseMessage? {
+        return try? JSONDecoder().decode(NoiseMessage.self, from: data)
+    }
+    
+    static func decodeWithError(from data: Data) -> NoiseMessage? {
+        do {
+            let decoded = try JSONDecoder().decode(NoiseMessage.self, from: data)
+            return decoded
+        } catch {
+            return nil
+        }
+    }
+    
+    // MARK: - Binary Encoding
+    
+    func toBinaryData() -> Data {
+        var data = Data()
+        data.appendUInt8(type)
+        data.appendUUID(sessionID)
+        data.appendData(payload)
+        return data
+    }
+    
+    static func fromBinaryData(_ data: Data) -> NoiseMessage? {
+        // Create defensive copy
+        let dataCopy = Data(data)
+        
+        var offset = 0
+        
+        guard let type = dataCopy.readUInt8(at: &offset),
+              let sessionID = dataCopy.readUUID(at: &offset),
+              let payload = dataCopy.readData(at: &offset) else { return nil }
+        
+        guard let messageType = NoiseMessageType(rawValue: type) else { return nil }
+        
+        return NoiseMessage(type: messageType, sessionID: sessionID, payload: payload)
+    }
+}
+
+// MARK: - Errors
+
+enum NoiseEncryptionError: Error {
+    case handshakeRequired
+    case sessionNotEstablished
+}

localPackages/Noise/Sources/Noise/NoiseRateLimiter.swift

@@ -0,0 +1,98 @@
+//
+// NoiseRateLimiter.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import BitLogger
+import BitFoundation
+import Foundation
+
+public final class NoiseRateLimiter {
+    private var handshakeTimestamps: [PeerID: [Date]] = [:]
+    private var messageTimestamps: [PeerID: [Date]] = [:]
+    
+    // Global rate limiting
+    private var globalHandshakeTimestamps: [Date] = []
+    private var globalMessageTimestamps: [Date] = []
+    
+    private let queue = DispatchQueue(label: "chat.bitchat.noise.ratelimit", attributes: .concurrent)
+
+    public init() {}
+
+    public func allowHandshake(from peerID: PeerID) -> Bool {
+        return queue.sync(flags: .barrier) {
+            let now = Date()
+            let oneMinuteAgo = now.addingTimeInterval(-60)
+            
+            // Check global rate limit first
+            globalHandshakeTimestamps = globalHandshakeTimestamps.filter { $0 > oneMinuteAgo }
+            if globalHandshakeTimestamps.count >= NoiseSecurityConstants.maxGlobalHandshakesPerMinute {
+                SecureLogger.warning("Global handshake rate limit exceeded: \(globalHandshakeTimestamps.count)/\(NoiseSecurityConstants.maxGlobalHandshakesPerMinute) per minute", category: .security)
+                return false
+            }
+            
+            // Check per-peer rate limit
+            var timestamps = handshakeTimestamps[peerID] ?? []
+            timestamps = timestamps.filter { $0 > oneMinuteAgo }
+            
+            if timestamps.count >= NoiseSecurityConstants.maxHandshakesPerMinute {
+                SecureLogger.warning("Per-peer handshake rate limit exceeded for \(peerID): \(timestamps.count)/\(NoiseSecurityConstants.maxHandshakesPerMinute) per minute", category: .security)
+                return false
+            }
+            
+            // Record new handshake
+            timestamps.append(now)
+            handshakeTimestamps[peerID] = timestamps
+            globalHandshakeTimestamps.append(now)
+            return true
+        }
+    }
+    
+    public func allowMessage(from peerID: PeerID) -> Bool {
+        return queue.sync(flags: .barrier) {
+            let now = Date()
+            let oneSecondAgo = now.addingTimeInterval(-1)
+            
+            // Check global rate limit first
+            globalMessageTimestamps = globalMessageTimestamps.filter { $0 > oneSecondAgo }
+            if globalMessageTimestamps.count >= NoiseSecurityConstants.maxGlobalMessagesPerSecond {
+                SecureLogger.warning("Global message rate limit exceeded: \(globalMessageTimestamps.count)/\(NoiseSecurityConstants.maxGlobalMessagesPerSecond) per second", category: .security)
+                return false
+            }
+            
+            // Check per-peer rate limit
+            var timestamps = messageTimestamps[peerID] ?? []
+            timestamps = timestamps.filter { $0 > oneSecondAgo }
+            
+            if timestamps.count >= NoiseSecurityConstants.maxMessagesPerSecond {
+                SecureLogger.warning("Per-peer message rate limit exceeded for \(peerID): \(timestamps.count)/\(NoiseSecurityConstants.maxMessagesPerSecond) per second", category: .security)
+                return false
+            }
+            
+            // Record new message
+            timestamps.append(now)
+            messageTimestamps[peerID] = timestamps
+            globalMessageTimestamps.append(now)
+            return true
+        }
+    }
+    
+    func reset(for peerID: PeerID) {
+        queue.async(flags: .barrier) {
+            self.handshakeTimestamps.removeValue(forKey: peerID)
+            self.messageTimestamps.removeValue(forKey: peerID)
+        }
+    }
+
+    public func resetAll() {
+        queue.async(flags: .barrier) {
+            self.handshakeTimestamps.removeAll()
+            self.messageTimestamps.removeAll()
+            self.globalHandshakeTimestamps.removeAll()
+            self.globalMessageTimestamps.removeAll()
+        }
+    }
+}

localPackages/Noise/Sources/Noise/NoiseSecurityConstants.swift

@@ -0,0 +1,37 @@
+//
+// NoiseSecurityConstants.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import Foundation
+
+public enum NoiseSecurityConstants {
+    // Maximum message size to prevent memory exhaustion
+    static let maxMessageSize = 65535 // 64KB as per Noise spec
+    
+    // Maximum handshake message size
+    static let maxHandshakeMessageSize = 2048 // 2KB to accommodate XX pattern
+    
+    // Session timeout - sessions older than this should be renegotiated
+    static let sessionTimeout: TimeInterval = 86400 // 24 hours
+    
+    // Maximum number of messages before rekey (2^64 - 1 is the nonce limit)
+    static let maxMessagesPerSession: UInt64 = 1_000_000_000 // 1 billion messages
+    
+    // Handshake timeout - abandon incomplete handshakes
+    static let handshakeTimeout: TimeInterval = 60 // 1 minute
+    
+    // Maximum concurrent sessions per peer
+    static let maxSessionsPerPeer = 3
+    
+    // Rate limiting
+    public static let maxHandshakesPerMinute = 10
+    public static let maxMessagesPerSecond = 100
+    
+    // Global rate limiting (across all peers)
+    public static let maxGlobalHandshakesPerMinute = 30
+    public static let maxGlobalMessagesPerSecond = 500
+}

localPackages/Noise/Sources/Noise/NoiseSecurityError.swift

@@ -0,0 +1,18 @@
+//
+// NoiseSecurityError.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import Foundation
+
+public enum NoiseSecurityError: Error {
+    case sessionExpired
+    case sessionExhausted
+    case messageTooLarge
+    case invalidPeerID
+    case rateLimitExceeded
+    case handshakeTimeout
+}

localPackages/Noise/Sources/Noise/NoiseSecurityValidator.swift

@@ -0,0 +1,22 @@
+//
+// NoiseSecurityValidator.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import Foundation
+
+public struct NoiseSecurityValidator {
+    
+    /// Validate message size
+    public static func validateMessageSize(_ data: Data) -> Bool {
+        return data.count <= NoiseSecurityConstants.maxMessageSize
+    }
+    
+    /// Validate handshake message size
+    public static func validateHandshakeMessageSize(_ data: Data) -> Bool {
+        return data.count <= NoiseSecurityConstants.maxHandshakeMessageSize
+    }
+}

localPackages/Noise/Sources/Noise/NoiseSession.swift

@@ -0,0 +1,230 @@
+//
+// NoiseSession.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import BitLogger
+import Foundation
+import CryptoKit
+import BitFoundation
+
+public class NoiseSession {
+    let peerID: PeerID
+    let role: NoiseRole
+    private let keychain: KeychainManagerProtocol
+    private var state: NoiseSessionState = .uninitialized
+    private var handshakeState: NoiseHandshakeState?
+    private var sendCipher: NoiseCipherState?
+    private var receiveCipher: NoiseCipherState?
+    
+    // Keys
+    private let localStaticKey: Curve25519.KeyAgreement.PrivateKey
+    private var remoteStaticPublicKey: Curve25519.KeyAgreement.PublicKey?
+    
+    // Handshake messages for retransmission
+    private var sentHandshakeMessages: [Data] = []
+    private var handshakeHash: Data?
+    
+    // Thread safety
+    private let sessionQueue = DispatchQueue(label: "chat.bitchat.noise.session", attributes: .concurrent)
+    
+    init(
+        peerID: PeerID,
+        role: NoiseRole,
+        keychain: KeychainManagerProtocol,
+        localStaticKey: Curve25519.KeyAgreement.PrivateKey,
+        remoteStaticKey: Curve25519.KeyAgreement.PublicKey? = nil
+    ) {
+        self.peerID = peerID
+        self.role = role
+        self.keychain = keychain
+        self.localStaticKey = localStaticKey
+        self.remoteStaticPublicKey = remoteStaticKey
+    }
+    
+    // MARK: - Handshake
+    
+    func startHandshake() throws -> Data {
+        return try sessionQueue.sync(flags: .barrier) {
+            guard case .uninitialized = state else {
+                throw NoiseSessionError.invalidState
+            }
+            
+            // For XX pattern, we don't need remote static key upfront
+            handshakeState = NoiseHandshakeState(
+                role: role,
+                pattern: .XX,
+                keychain: keychain,
+                localStaticKey: localStaticKey,
+                remoteStaticKey: nil
+            )
+            
+            state = .handshaking
+            
+            // Only initiator writes the first message
+            if role == .initiator {
+                let message = try handshakeState!.writeMessage()
+                sentHandshakeMessages.append(message)
+                return message
+            } else {
+                // Responder doesn't send first message in XX pattern
+                return Data()
+            }
+        }
+    }
+    
+    func processHandshakeMessage(_ message: Data) throws -> Data? {
+        return try sessionQueue.sync(flags: .barrier) {
+            SecureLogger.debug("NoiseSession[\(peerID)]: Processing handshake message, current state: \(state), role: \(role)")
+            
+            // Initialize handshake state if needed (for responders)
+            if state == .uninitialized && role == .responder {
+                handshakeState = NoiseHandshakeState(
+                    role: role,
+                    pattern: .XX,
+                    keychain: keychain,
+                    localStaticKey: localStaticKey,
+                    remoteStaticKey: nil
+                )
+                state = .handshaking
+                SecureLogger.debug("NoiseSession[\(peerID)]: Initialized handshake state for responder")
+            }
+            
+            guard case .handshaking = state, let handshake = handshakeState else {
+                throw NoiseSessionError.invalidState
+            }
+            
+            // Process incoming message
+            _ = try handshake.readMessage(message)
+            SecureLogger.debug("NoiseSession[\(peerID)]: Read handshake message, checking if complete")
+            
+            // Check if handshake is complete
+            if handshake.isHandshakeComplete() {
+                // Get transport ciphers and handshake hash (hash captured before split clears state)
+                let (send, receive, hash) = try handshake.getTransportCiphers(useExtractedNonce: true)
+                sendCipher = send
+                receiveCipher = receive
+
+                // Store remote static key
+                remoteStaticPublicKey = handshake.getRemoteStaticPublicKey()
+
+                // Store handshake hash for channel binding
+                handshakeHash = hash
+
+                state = .established
+                handshakeState = nil // Clear handshake state
+
+                SecureLogger.debug("NoiseSession[\(peerID)]: Handshake complete (no response needed), transitioning to established")
+                SecureLogger.info(.handshakeCompleted(peerID: peerID.id))
+
+                return nil
+            } else {
+                // Generate response
+                let response = try handshake.writeMessage()
+                sentHandshakeMessages.append(response)
+                SecureLogger.debug("NoiseSession[\(peerID)]: Generated handshake response of size \(response.count)")
+                
+                // Check if handshake is complete after writing
+                if handshake.isHandshakeComplete() {
+                    // Get transport ciphers and handshake hash (hash captured before split clears state)
+                    let (send, receive, hash) = try handshake.getTransportCiphers(useExtractedNonce: true)
+                    sendCipher = send
+                    receiveCipher = receive
+
+                    // Store remote static key
+                    remoteStaticPublicKey = handshake.getRemoteStaticPublicKey()
+
+                    // Store handshake hash for channel binding
+                    handshakeHash = hash
+
+                    state = .established
+                    handshakeState = nil // Clear handshake state
+
+                    SecureLogger.debug("NoiseSession[\(peerID)]: Handshake complete after writing response, transitioning to established")
+                    SecureLogger.info(.handshakeCompleted(peerID: peerID.id))
+                }
+                
+                return response
+            }
+        }
+    }
+    
+    // MARK: - Transport
+    
+    func encrypt(_ plaintext: Data) throws -> Data {
+        return try sessionQueue.sync(flags: .barrier) {
+            guard case .established = state, let cipher = sendCipher else {
+                throw NoiseSessionError.notEstablished
+            }
+            
+            return try cipher.encrypt(plaintext: plaintext)
+        }
+    }
+    
+    func decrypt(_ ciphertext: Data) throws -> Data {
+        return try sessionQueue.sync(flags: .barrier) {
+            guard case .established = state, let cipher = receiveCipher else {
+                throw NoiseSessionError.notEstablished
+            }
+            
+            return try cipher.decrypt(ciphertext: ciphertext)
+        }
+    }
+    
+    // MARK: - State Management
+    
+    func getState() -> NoiseSessionState {
+        return sessionQueue.sync {
+            return state
+        }
+    }
+    
+    public func isEstablished() -> Bool {
+        return sessionQueue.sync {
+            if case .established = state {
+                return true
+            }
+            return false
+        }
+    }
+    
+    func getRemoteStaticPublicKey() -> Curve25519.KeyAgreement.PublicKey? {
+        return sessionQueue.sync {
+            return remoteStaticPublicKey
+        }
+    }
+    
+    func reset() {
+        sessionQueue.sync(flags: .barrier) {
+            let wasEstablished = state == .established
+            state = .uninitialized
+            handshakeState = nil
+            
+            // Clear sensitive cipher states
+            sendCipher?.clearSensitiveData()
+            receiveCipher?.clearSensitiveData()
+            sendCipher = nil
+            receiveCipher = nil
+            
+            // Clear sent handshake messages
+            for i in 0..<sentHandshakeMessages.count {
+                var message = sentHandshakeMessages[i]
+                keychain.secureClear(&message)
+            }
+            sentHandshakeMessages.removeAll()
+            
+            // Clear handshake hash
+            if handshakeHash != nil {
+                keychain.secureClear(&handshakeHash!)
+            }
+            handshakeHash = nil
+            
+            if wasEstablished {
+                SecureLogger.info(.sessionExpired(peerID: peerID.id))
+            }
+        }
+    }
+}

localPackages/Noise/Sources/Noise/NoiseSessionError.swift

@@ -0,0 +1,14 @@
+//
+// NoiseSessionError.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+public enum NoiseSessionError: Error, Equatable {
+    case invalidState
+    case notEstablished
+    case sessionNotFound
+    case alreadyEstablished
+}

localPackages/Noise/Sources/Noise/NoiseSessionManager.swift

@@ -0,0 +1,223 @@
+//
+// NoiseSessionManager.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import BitLogger
+import CryptoKit
+import Foundation
+import BitFoundation
+
+public final class NoiseSessionManager {
+    private var sessions: [PeerID: NoiseSession] = [:]
+    private let localStaticKey: Curve25519.KeyAgreement.PrivateKey
+    private let keychain: KeychainManagerProtocol
+    private let sessionFactory: (PeerID, NoiseRole) -> NoiseSession
+    private let managerQueue = DispatchQueue(label: "chat.bitchat.noise.manager", attributes: .concurrent)
+    
+    // Callbacks
+    public var onSessionEstablished: ((PeerID, Curve25519.KeyAgreement.PublicKey) -> Void)?
+    var onSessionFailed: ((PeerID, Error) -> Void)?
+    
+    public init(localStaticKey: Curve25519.KeyAgreement.PrivateKey, keychain: KeychainManagerProtocol) {
+        self.localStaticKey = localStaticKey
+        self.keychain = keychain
+        self.sessionFactory = { peerID, role in
+            SecureNoiseSession(
+                peerID: peerID,
+                role: role,
+                keychain: keychain,
+                localStaticKey: localStaticKey
+            )
+        }
+    }
+
+    #if DEBUG
+    init(
+        localStaticKey: Curve25519.KeyAgreement.PrivateKey,
+        keychain: KeychainManagerProtocol,
+        sessionFactory: @escaping (PeerID, NoiseRole) -> NoiseSession
+    ) {
+        self.localStaticKey = localStaticKey
+        self.keychain = keychain
+        self.sessionFactory = sessionFactory
+    }
+    #endif
+    
+    // MARK: - Session Management
+    
+    public func getSession(for peerID: PeerID) -> NoiseSession? {
+        return managerQueue.sync {
+            return sessions[peerID]
+        }
+    }
+    
+    public func removeSession(for peerID: PeerID) {
+        managerQueue.sync(flags: .barrier) {
+            if let session = sessions.removeValue(forKey: peerID) {
+                session.reset() // Clear sensitive data before removing
+            }
+        }
+    }
+
+    public func removeAllSessions() {
+        managerQueue.sync(flags: .barrier) {
+            for (_, session) in sessions {
+                session.reset()
+            }
+            sessions.removeAll()
+        }
+    }
+    
+    // MARK: - Handshake Helpers
+    
+    public func initiateHandshake(with peerID: PeerID) throws -> Data {
+        return try managerQueue.sync(flags: .barrier) {
+            // Check if we already have an established session
+            if let existingSession = sessions[peerID], existingSession.isEstablished() {
+                // Session already established, don't recreate
+                throw NoiseSessionError.alreadyEstablished
+            }
+            
+            // Remove any existing non-established session
+            if let existingSession = sessions[peerID], !existingSession.isEstablished() {
+                _ = sessions.removeValue(forKey: peerID)
+            }
+            
+            // Create new initiator session
+            let session = sessionFactory(peerID, .initiator)
+            sessions[peerID] = session
+            
+            do {
+                let handshakeData = try session.startHandshake()
+                return handshakeData
+            } catch {
+                // Clean up failed session
+                _ = sessions.removeValue(forKey: peerID)
+                SecureLogger.error(.handshakeFailed(peerID: peerID.id, error: error.localizedDescription))
+                throw error
+            }
+        }
+    }
+    
+    public func handleIncomingHandshake(from peerID: PeerID, message: Data) throws -> Data? {
+        // Process everything within the synchronized block to prevent race conditions
+        return try managerQueue.sync(flags: .barrier) {
+            var shouldCreateNew = false
+            var existingSession: NoiseSession? = nil
+            
+            if let existing = sessions[peerID] {
+                // If we have an established session, the peer must have cleared their session
+                // for a good reason (e.g., decryption failure, restart, etc.)
+                // We should accept the new handshake to re-establish encryption
+                if existing.isEstablished() {
+                    SecureLogger.info("Accepting handshake from \(peerID) despite existing session - peer likely cleared their session", category: .session)
+                    _ = sessions.removeValue(forKey: peerID)
+                    shouldCreateNew = true
+                } else {
+                    // If we're in the middle of a handshake and receive a new initiation,
+                    // reset and start fresh (the other side may have restarted)
+                    if existing.getState() == .handshaking && message.count == 32 {
+                        _ = sessions.removeValue(forKey: peerID)
+                        shouldCreateNew = true
+                    } else {
+                        existingSession = existing
+                    }
+                }
+            } else {
+                shouldCreateNew = true
+            }
+            
+            // Get or create session
+            let session: NoiseSession
+            if shouldCreateNew {
+                let newSession = sessionFactory(peerID, .responder)
+                sessions[peerID] = newSession
+                session = newSession
+            } else {
+                session = existingSession!
+            }
+            
+            // Process the handshake message within the synchronized block
+            do {
+                let response = try session.processHandshakeMessage(message)
+                
+                // Check if session is established after processing
+                if session.isEstablished() {
+                    if let remoteKey = session.getRemoteStaticPublicKey() {
+                        // Schedule callback outside the synchronized block to prevent deadlock
+                        DispatchQueue.global().async { [weak self] in
+                            self?.onSessionEstablished?(peerID, remoteKey)
+                        }
+                    }
+                }
+                
+                return response
+            } catch {
+                // Reset the session on handshake failure so next attempt can start fresh
+                _ = sessions.removeValue(forKey: peerID)
+                
+                // Schedule callback outside the synchronized block to prevent deadlock
+                DispatchQueue.global().async { [weak self] in
+                    self?.onSessionFailed?(peerID, error)
+                }
+                
+                SecureLogger.error(.handshakeFailed(peerID: peerID.id, error: error.localizedDescription))
+                throw error
+            }
+        }
+    }
+    
+    // MARK: - Encryption/Decryption
+    
+    public func encrypt(_ plaintext: Data, for peerID: PeerID) throws -> Data {
+        guard let session = getSession(for: peerID) else {
+            throw NoiseSessionError.sessionNotFound
+        }
+        
+        return try session.encrypt(plaintext)
+    }
+    
+    public func decrypt(_ ciphertext: Data, from peerID: PeerID) throws -> Data {
+        guard let session = getSession(for: peerID) else {
+            throw NoiseSessionError.sessionNotFound
+        }
+        
+        return try session.decrypt(ciphertext)
+    }
+    
+    // MARK: - Key Management
+    
+    public func getRemoteStaticKey(for peerID: PeerID) -> Curve25519.KeyAgreement.PublicKey? {
+        return getSession(for: peerID)?.getRemoteStaticPublicKey()
+    }
+    
+    // MARK: - Session Rekeying
+    
+    public func getSessionsNeedingRekey() -> [(peerID: PeerID, needsRekey: Bool)] {
+        return managerQueue.sync {
+            var needingRekey: [(peerID: PeerID, needsRekey: Bool)] = []
+            
+            for (peerID, session) in sessions {
+                if let secureSession = session as? SecureNoiseSession,
+                   secureSession.isEstablished(),
+                   secureSession.needsRenegotiation() {
+                    needingRekey.append((peerID: peerID, needsRekey: true))
+                }
+            }
+            
+            return needingRekey
+        }
+    }
+    
+    public func initiateRekey(for peerID: PeerID) throws {
+        // Remove old session
+        removeSession(for: peerID)
+        
+        // Initiate new handshake
+        _ = try initiateHandshake(with: peerID)
+    }
+}

localPackages/Noise/Sources/Noise/NoiseSessionState.swift

@@ -0,0 +1,13 @@
+//
+// NoiseSessionState.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+enum NoiseSessionState: Equatable {
+    case uninitialized
+    case handshaking
+    case established
+}

localPackages/Noise/Sources/Noise/SecureNoiseSession.swift

@@ -0,0 +1,85 @@
+//
+// SecureNoiseSession.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import Foundation
+
+final class SecureNoiseSession: NoiseSession {
+    private(set) var messageCount: UInt64 = 0
+    private var sessionStartTime = Date()
+    private(set) var lastActivityTime = Date()
+    
+    override func encrypt(_ plaintext: Data) throws -> Data {
+        // Check session age
+        if Date().timeIntervalSince(sessionStartTime) > NoiseSecurityConstants.sessionTimeout {
+            throw NoiseSecurityError.sessionExpired
+        }
+        
+        // Check message count
+        if messageCount >= NoiseSecurityConstants.maxMessagesPerSession {
+            throw NoiseSecurityError.sessionExhausted
+        }
+        
+        // Validate message size
+        guard NoiseSecurityValidator.validateMessageSize(plaintext) else {
+            throw NoiseSecurityError.messageTooLarge
+        }
+        
+        let encrypted = try super.encrypt(plaintext)
+        messageCount += 1
+        lastActivityTime = Date()
+        
+        return encrypted
+    }
+    
+    override func decrypt(_ ciphertext: Data) throws -> Data {
+        // Check session age
+        if Date().timeIntervalSince(sessionStartTime) > NoiseSecurityConstants.sessionTimeout {
+            throw NoiseSecurityError.sessionExpired
+        }
+        
+        // Validate message size
+        guard NoiseSecurityValidator.validateMessageSize(ciphertext) else {
+            throw NoiseSecurityError.messageTooLarge
+        }
+        
+        let decrypted = try super.decrypt(ciphertext)
+        lastActivityTime = Date()
+        
+        return decrypted
+    }
+    
+    func needsRenegotiation() -> Bool {
+        // Check if we've used more than 90% of message limit
+        let messageThreshold = UInt64(Double(NoiseSecurityConstants.maxMessagesPerSession) * 0.9)
+        if messageCount >= messageThreshold {
+            return true
+        }
+        
+        // Check if last activity was more than 30 minutes ago
+        if Date().timeIntervalSince(lastActivityTime) > NoiseSecurityConstants.sessionTimeout {
+            return true
+        }
+        
+        return false
+    }
+    
+    // MARK: - Testing Support
+    #if DEBUG
+    func setLastActivityTimeForTesting(_ date: Date) {
+        lastActivityTime = date
+    }
+    
+    func setMessageCountForTesting(_ count: UInt64) {
+        messageCount = count
+    }
+
+    func setSessionStartTimeForTesting(_ date: Date) {
+        sessionStartTime = date
+    }
+    #endif
+}

localPackages/Noise/Tests/NoiseTests/MockKeychain.swift

@@ -0,0 +1,201 @@
+//
+// MockKeychain.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import Foundation
+import BitFoundation
+
+// TODO: Create a module for test helpers
+final class MockKeychain: KeychainManagerProtocol {
+    private var storage: [String: Data] = [:]
+    private var serviceStorage: [String: [String: Data]] = [:]
+
+    // BCH-01-009: Configurable error simulation for testing
+    var simulatedReadError: KeychainReadResult?
+    var simulatedSaveError: KeychainSaveResult?
+
+    func saveIdentityKey(_ keyData: Data, forKey key: String) -> Bool {
+        storage[key] = keyData
+        return true
+    }
+
+    func getIdentityKey(forKey key: String) -> Data? {
+        storage[key]
+    }
+
+    func deleteIdentityKey(forKey key: String) -> Bool {
+        storage.removeValue(forKey: key)
+        return true
+    }
+
+    func deleteAllKeychainData() -> Bool {
+        storage.removeAll()
+        serviceStorage.removeAll()
+        return true
+    }
+
+    func secureClear(_ data: inout Data) {
+        data = Data()
+    }
+
+    func secureClear(_ string: inout String) {
+        string = ""
+    }
+
+    func verifyIdentityKeyExists() -> Bool {
+        storage["identity_noiseStaticKey"] != nil
+    }
+
+    // BCH-01-009: New methods with proper error classification
+    func getIdentityKeyWithResult(forKey key: String) -> KeychainReadResult {
+        if let simulated = simulatedReadError {
+            return simulated
+        }
+        if let data = storage[key] {
+            return .success(data)
+        }
+        return .itemNotFound
+    }
+
+    func saveIdentityKeyWithResult(_ keyData: Data, forKey key: String) -> KeychainSaveResult {
+        if let simulated = simulatedSaveError {
+            return simulated
+        }
+        storage[key] = keyData
+        return .success
+    }
+
+    // MARK: - Generic Data Storage (consolidated from KeychainHelper)
+
+    func save(key: String, data: Data, service: String, accessible: CFString?) {
+        if serviceStorage[service] == nil {
+            serviceStorage[service] = [:]
+        }
+        serviceStorage[service]?[key] = data
+    }
+
+    func load(key: String, service: String) -> Data? {
+        serviceStorage[service]?[key]
+    }
+
+    func delete(key: String, service: String) {
+        serviceStorage[service]?.removeValue(forKey: key)
+    }
+}
+
+/// Typealias for backwards compatibility with tests using MockKeychainHelper
+typealias MockKeychainHelper = MockKeychain
+
+/// Mock keychain that tracks secureClear calls for testing DH secret clearing
+final class TrackingMockKeychain: KeychainManagerProtocol {
+    private var storage: [String: Data] = [:]
+    private var serviceStorage: [String: [String: Data]] = [:]
+
+    /// Thread-safe counter for secureClear calls
+    private let lock = NSLock()
+    private var _secureClearDataCallCount = 0
+    private var _secureClearStringCallCount = 0
+
+    // BCH-01-009: Configurable error simulation for testing
+    var simulatedReadError: KeychainReadResult?
+    var simulatedSaveError: KeychainSaveResult?
+
+    var secureClearDataCallCount: Int {
+        lock.lock()
+        defer { lock.unlock() }
+        return _secureClearDataCallCount
+    }
+
+    var secureClearStringCallCount: Int {
+        lock.lock()
+        defer { lock.unlock() }
+        return _secureClearStringCallCount
+    }
+
+    var totalSecureClearCallCount: Int {
+        return secureClearDataCallCount + secureClearStringCallCount
+    }
+
+    func resetCounts() {
+        lock.lock()
+        defer { lock.unlock() }
+        _secureClearDataCallCount = 0
+        _secureClearStringCallCount = 0
+    }
+
+    func saveIdentityKey(_ keyData: Data, forKey key: String) -> Bool {
+        storage[key] = keyData
+        return true
+    }
+
+    func getIdentityKey(forKey key: String) -> Data? {
+        storage[key]
+    }
+
+    func deleteIdentityKey(forKey key: String) -> Bool {
+        storage.removeValue(forKey: key)
+        return true
+    }
+
+    func deleteAllKeychainData() -> Bool {
+        storage.removeAll()
+        serviceStorage.removeAll()
+        return true
+    }
+
+    func secureClear(_ data: inout Data) {
+        lock.lock()
+        _secureClearDataCallCount += 1
+        lock.unlock()
+        data = Data()
+    }
+
+    func secureClear(_ string: inout String) {
+        lock.lock()
+        _secureClearStringCallCount += 1
+        lock.unlock()
+        string = ""
+    }
+
+    func verifyIdentityKeyExists() -> Bool {
+        storage["identity_noiseStaticKey"] != nil
+    }
+
+    // BCH-01-009: New methods with proper error classification
+    func getIdentityKeyWithResult(forKey key: String) -> KeychainReadResult {
+        if let simulated = simulatedReadError {
+            return simulated
+        }
+        if let data = storage[key] {
+            return .success(data)
+        }
+        return .itemNotFound
+    }
+
+    func saveIdentityKeyWithResult(_ keyData: Data, forKey key: String) -> KeychainSaveResult {
+        if let simulated = simulatedSaveError {
+            return simulated
+        }
+        storage[key] = keyData
+        return .success
+    }
+
+    func save(key: String, data: Data, service: String, accessible: CFString?) {
+        if serviceStorage[service] == nil {
+            serviceStorage[service] = [:]
+        }
+        serviceStorage[service]?[key] = data
+    }
+
+    func load(key: String, service: String) -> Data? {
+        serviceStorage[service]?[key]
+    }
+
+    func delete(key: String, service: String) {
+        serviceStorage[service]?.removeValue(forKey: key)
+    }
+}

localPackages/Noise/Tests/NoiseTests/NoiseCoverageTests.swift

@@ -0,0 +1,867 @@
+import CryptoKit
+import Foundation
+import Testing
+import BitFoundation
+@testable import Noise
+
+@Suite("Noise Coverage Tests")
+struct NoiseCoverageTests {
+    private let keychain = MockKeychain()
+    private let aliceStaticKey = Curve25519.KeyAgreement.PrivateKey()
+    private let bobStaticKey = Curve25519.KeyAgreement.PrivateKey()
+    private let charlieStaticKey = Curve25519.KeyAgreement.PrivateKey()
+
+    private let alicePeerID = PeerID(str: "0011223344556677")
+    private let bobPeerID = PeerID(str: "8899aabbccddeeff")
+    private let charliePeerID = PeerID(str: "fedcba9876543210")
+
+    @Test("Protocol metadata and handshake patterns expose expected values")
+    func protocolMetadataAndHandshakePatterns() {
+        let ikName = NoiseProtocolName(pattern: NoisePattern.IK.patternName)
+        #expect(ikName.pattern == "IK")
+        #expect(ikName.dh == "25519")
+        #expect(ikName.cipher == "ChaChaPoly")
+        #expect(ikName.hash == "SHA256")
+        #expect(ikName.fullName == "Noise_IK_25519_ChaChaPoly_SHA256")
+
+        #expect(NoisePattern.XX.patternName == "XX")
+        #expect(NoisePattern.IK.patternName == "IK")
+        #expect(NoisePattern.NK.patternName == "NK")
+
+        let ikPatterns = NoisePattern.IK.messagePatterns
+        #expect(ikPatterns.count == 2)
+        #expect(ikPatterns[0] == [.e, .es, .s, .ss])
+        #expect(ikPatterns[1] == [.e, .ee, .se])
+
+        let nkPatterns = NoisePattern.NK.messagePatterns
+        #expect(nkPatterns.count == 2)
+        #expect(nkPatterns[0] == [.e, .es])
+        #expect(nkPatterns[1] == [.e, .ee])
+    }
+
+    @Test("Symmetric state supports long protocol names and mixKeyAndHash")
+    func symmetricStateLongNameAndMixKeyAndHash() {
+        let longName = String(repeating: "NoiseProtocol_", count: 3)
+        let symmetricState = NoiseSymmetricState(protocolName: longName)
+        let initialHash = symmetricState.getHandshakeHash()
+
+        #expect(initialHash.count == 32)
+        #expect(!symmetricState.hasCipherKey())
+
+        symmetricState.mixKeyAndHash(Data("input-key-material".utf8))
+
+        #expect(symmetricState.hasCipherKey())
+        #expect(symmetricState.getHandshakeHash() != initialHash)
+    }
+
+    @Test("Cipher state rejects duplicate and stale extracted nonces")
+    func cipherStateRejectsDuplicateAndStaleNonces() throws {
+        let key = SymmetricKey(size: .bits256)
+        let receiver = NoiseCipherState(key: key, useExtractedNonce: true)
+        let initialPayload = try makeExtractedNoncePayload(
+            key: key,
+            nonce: 0,
+            plaintext: Data("nonce-0".utf8)
+        )
+
+        let initialPlaintext = try receiver.decrypt(ciphertext: initialPayload)
+        #expect(initialPlaintext == Data("nonce-0".utf8))
+
+        #expect(throws: (any Error).self) {
+            try receiver.decrypt(ciphertext: initialPayload)
+        }
+
+        for nonce in 1...1024 {
+            let payload = try makeExtractedNoncePayload(
+                key: key,
+                nonce: UInt64(nonce),
+                plaintext: Data("nonce-\(nonce)".utf8)
+            )
+            let plaintext = try receiver.decrypt(ciphertext: payload)
+            #expect(plaintext == Data("nonce-\(nonce)".utf8))
+        }
+
+        #expect(throws: (any Error).self) {
+            try receiver.decrypt(ciphertext: initialPayload)
+        }
+    }
+
+    @Test("Cipher state handles large nonce jumps and associated-data mismatches")
+    func cipherStateHandlesLargeJumpsAndAADMismatch() throws {
+        let key = SymmetricKey(size: .bits256)
+        let extractedReceiver = NoiseCipherState(key: key, useExtractedNonce: true)
+
+        let jumped = try makeExtractedNoncePayload(
+            key: key,
+            nonce: 1500,
+            plaintext: Data("future".utf8)
+        )
+        let slightlyOlder = try makeExtractedNoncePayload(
+            key: key,
+            nonce: 1499,
+            plaintext: Data("older".utf8)
+        )
+        let tooOld = try makeExtractedNoncePayload(
+            key: key,
+            nonce: 100,
+            plaintext: Data("ancient".utf8)
+        )
+
+        #expect(try extractedReceiver.decrypt(ciphertext: jumped) == Data("future".utf8))
+        #expect(try extractedReceiver.decrypt(ciphertext: slightlyOlder) == Data("older".utf8))
+        #expect(throws: (any Error).self) {
+            try extractedReceiver.decrypt(ciphertext: tooOld)
+        }
+
+        let sender = NoiseCipherState(key: key)
+        let receiver = NoiseCipherState(key: key)
+        let plaintext = Data("associated-data".utf8)
+        let aad = Data("good-aad".utf8)
+        let ciphertext = try sender.encrypt(plaintext: plaintext, associatedData: aad)
+
+        #expect(throws: (any Error).self) {
+            try receiver.decrypt(ciphertext: ciphertext, associatedData: Data("bad-aad".utf8))
+        }
+        #expect(try receiver.decrypt(ciphertext: ciphertext, associatedData: aad) == plaintext)
+        #expect(throws: (any Error).self) {
+            try receiver.decrypt(ciphertext: Data(repeating: 0xAA, count: 15))
+        }
+    }
+
+    @Test("Cipher state covers nonce guard rails and extracted payload bounds")
+    func cipherStateCoversNonceGuardRailsAndExtractedPayloadBounds() throws {
+        let uninitializedCipher = NoiseCipherState()
+        #expect(throws: NoiseError.uninitializedCipher) {
+            try uninitializedCipher.encrypt(plaintext: Data("missing-key".utf8))
+        }
+        #expect(throws: NoiseError.uninitializedCipher) {
+            try uninitializedCipher.decrypt(ciphertext: Data(repeating: 0x00, count: 16))
+        }
+        #expect(try uninitializedCipher.extractNonceFromCiphertextPayloadForTesting(Data([0x00, 0x01, 0x02])) == nil)
+
+        let key = SymmetricKey(size: .bits256)
+
+        let highNonceCipher = NoiseCipherState(key: key)
+        highNonceCipher.setNonceForTesting(1_000_000_001)
+        #expect(throws: Never.self) {
+            _ = try highNonceCipher.encrypt(plaintext: Data("high-nonce".utf8))
+        }
+
+        let exhaustedCipher = NoiseCipherState(key: key)
+        exhaustedCipher.setNonceForTesting(UInt64(UInt32.max))
+        #expect(throws: NoiseError.nonceExceeded) {
+            try exhaustedCipher.encrypt(plaintext: Data("nonce-limit".utf8))
+        }
+    }
+
+    @Test("Handshake validation rejects malformed keys and messages")
+    func handshakeValidationRejectsMalformedInputs() throws {
+        let responder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        #expect(throws: (any Error).self) {
+            try responder.readMessage(Data(repeating: 0x00, count: 31))
+        }
+
+        let invalidKeys = [
+            Data(),
+            Data(repeating: 0x00, count: 32),
+            Data([0x01] + Array(repeating: 0x00, count: 31)),
+            Data(repeating: 0xFF, count: 32),
+        ]
+
+        for invalidKey in invalidKeys {
+            #expect(throws: (any Error).self) {
+                _ = try NoiseHandshakeState.validatePublicKey(invalidKey)
+            }
+        }
+
+        let valid = aliceStaticKey.publicKey.rawRepresentation
+        let roundTripped = try NoiseHandshakeState.validatePublicKey(valid)
+        #expect(roundTripped.rawRepresentation == valid)
+
+        let initiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey
+        )
+        let responderForTamper = NoiseHandshakeState(
+            role: .responder,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        let message1 = try initiator.writeMessage()
+        _ = try responderForTamper.readMessage(message1)
+        var message2 = try responderForTamper.writeMessage()
+        message2[40] ^= 0x01
+
+        #expect(throws: (any Error).self) {
+            try initiator.readMessage(message2)
+        }
+    }
+
+    @Test("Handshake readers reject invalid ephemeral and truncated static payloads")
+    func handshakeReadersRejectInvalidEphemeralAndTruncatedStaticPayloads() throws {
+        let invalidEphemeralResponder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        #expect(throws: NoiseError.invalidMessage) {
+            try invalidEphemeralResponder.readMessage(Data(repeating: 0x00, count: 32))
+        }
+
+        let truncatedStaticInitiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey
+        )
+        _ = try truncatedStaticInitiator.writeMessage()
+        let responderEphemeralOnly = Curve25519.KeyAgreement.PrivateKey().publicKey.rawRepresentation
+
+        #expect(throws: NoiseError.invalidMessage) {
+            try truncatedStaticInitiator.readMessage(responderEphemeralOnly)
+        }
+    }
+
+    @Test("IK handshake completes and supports transport messages")
+    func ikHandshakeCompletesAndSupportsTransportMessages() throws {
+        let initiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .IK,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey,
+            remoteStaticKey: bobStaticKey.publicKey
+        )
+        let responder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .IK,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        let outboundPayload = Data("ik-outbound".utf8)
+        let returnPayload = Data("ik-return".utf8)
+        let message1 = try initiator.writeMessage(payload: outboundPayload)
+
+        #expect(try responder.readMessage(message1) == outboundPayload)
+
+        let message2 = try responder.writeMessage(payload: returnPayload)
+        #expect(try initiator.readMessage(message2) == returnPayload)
+
+        #expect(initiator.isHandshakeComplete())
+        #expect(responder.isHandshakeComplete())
+
+        let (initiatorSend, initiatorReceive, initiatorHash) = try initiator.getTransportCiphers(
+            useExtractedNonce: true
+        )
+        let (responderSend, responderReceive, responderHash) = try responder.getTransportCiphers(
+            useExtractedNonce: true
+        )
+
+        #expect(initiatorHash == responderHash)
+
+        let clientCiphertext = try initiatorSend.encrypt(plaintext: Data("ik-transport".utf8))
+        #expect(try responderReceive.decrypt(ciphertext: clientCiphertext) == Data("ik-transport".utf8))
+
+        let serverCiphertext = try responderSend.encrypt(plaintext: Data("ik-response".utf8))
+        #expect(try initiatorReceive.decrypt(ciphertext: serverCiphertext) == Data("ik-response".utf8))
+    }
+
+    @Test("NK handshake requires a responder static key and supports transport messages")
+    func nkHandshakeRequiresStaticAndSupportsTransportMessages() throws {
+        let missingStaticInitiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .NK,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey
+        )
+
+        #expect(throws: (any Error).self) {
+            try missingStaticInitiator.writeMessage()
+        }
+
+        let initiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .NK,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey,
+            remoteStaticKey: bobStaticKey.publicKey
+        )
+        let responder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .NK,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        let outboundPayload = Data("nk-outbound".utf8)
+        let returnPayload = Data("nk-return".utf8)
+        let message1 = try initiator.writeMessage(payload: outboundPayload)
+        #expect(try responder.readMessage(message1) == outboundPayload)
+
+        let message2 = try responder.writeMessage(payload: returnPayload)
+        #expect(try initiator.readMessage(message2) == returnPayload)
+
+        #expect(initiator.isHandshakeComplete())
+        #expect(responder.isHandshakeComplete())
+
+        let (initiatorSend, initiatorReceive, initiatorHash) = try initiator.getTransportCiphers(
+            useExtractedNonce: true
+        )
+        let (responderSend, responderReceive, responderHash) = try responder.getTransportCiphers(
+            useExtractedNonce: true
+        )
+
+        #expect(initiatorHash == responderHash)
+
+        let clientCiphertext = try initiatorSend.encrypt(plaintext: Data("nk-transport".utf8))
+        #expect(try responderReceive.decrypt(ciphertext: clientCiphertext) == Data("nk-transport".utf8))
+
+        let serverCiphertext = try responderSend.encrypt(plaintext: Data("nk-response".utf8))
+        #expect(try initiatorReceive.decrypt(ciphertext: serverCiphertext) == Data("nk-response".utf8))
+    }
+
+    @Test("Responder-side NK writes require peer ephemeral input")
+    func responderWritesRequirePeerEphemeralInput() {
+        let nkResponder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .NK,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        #expect(throws: NoiseError.missingKeys) {
+            try nkResponder.writeMessage()
+        }
+    }
+
+    @Test("Direct DH helpers reject missing keys across all patterns")
+    func directDHHelpersRejectMissingKeysAcrossAllPatterns() throws {
+        let eeState = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey
+        )
+        #expect(throws: NoiseError.missingKeys) {
+            try eeState.performDHOperationForTesting(.ee)
+        }
+
+        let esInitiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey
+        )
+        #expect(throws: NoiseError.missingKeys) {
+            try esInitiator.performDHOperationForTesting(.es)
+        }
+
+        let esResponder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: nil
+        )
+        #expect(throws: NoiseError.missingKeys) {
+            try esResponder.performDHOperationForTesting(.es)
+        }
+
+        let seInitiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: nil
+        )
+        #expect(throws: NoiseError.missingKeys) {
+            try seInitiator.performDHOperationForTesting(.se)
+        }
+
+        let seResponder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+        #expect(throws: NoiseError.missingKeys) {
+            try seResponder.performDHOperationForTesting(.se)
+        }
+
+        let ssState = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: nil
+        )
+        #expect(throws: NoiseError.missingKeys) {
+            try ssState.performDHOperationForTesting(.ss)
+        }
+
+        #expect(throws: Never.self) {
+            try eeState.performDHOperationForTesting(.e)
+            try eeState.performDHOperationForTesting(.s)
+        }
+    }
+
+    @Test("Prepared handshake writers cover remaining missing-key branches")
+    func preparedHandshakeWritersCoverRemainingMissingKeyBranches() {
+        let eeResponder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .NK,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+        eeResponder.setCurrentPatternForTesting(1)
+        #expect(throws: NoiseError.missingKeys) {
+            try eeResponder.writeMessage()
+        }
+
+        let seInitiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey
+        )
+        seInitiator.setCurrentPatternForTesting(2)
+        #expect(throws: NoiseError.missingKeys) {
+            try seInitiator.writeMessage()
+        }
+
+        let seResponder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .IK,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+        seResponder.setCurrentPatternForTesting(1)
+        seResponder.setRemoteEphemeralPublicKeyForTesting(Curve25519.KeyAgreement.PrivateKey().publicKey)
+        #expect(throws: NoiseError.missingKeys) {
+            try seResponder.writeMessage()
+        }
+    }
+
+    @Test("Completed handshakes reject additional reads and writes")
+    func completedHandshakesRejectAdditionalReadsAndWrites() throws {
+        let initiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .IK,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey,
+            remoteStaticKey: bobStaticKey.publicKey
+        )
+        let responder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .IK,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        let message1 = try initiator.writeMessage(payload: Data("first".utf8))
+        _ = try responder.readMessage(message1)
+        let message2 = try responder.writeMessage(payload: Data("second".utf8))
+        _ = try initiator.readMessage(message2)
+
+        #expect(throws: NoiseError.handshakeComplete) {
+            try initiator.writeMessage()
+        }
+        #expect(throws: NoiseError.handshakeComplete) {
+            try responder.readMessage(message1)
+        }
+    }
+
+    @Test("XX final message requires a local static key")
+    func xxFinalMessageRequiresLocalStaticKey() throws {
+        let initiator = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: nil
+        )
+        let responder = NoiseHandshakeState(
+            role: .responder,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        let message1 = try initiator.writeMessage()
+        _ = try responder.readMessage(message1)
+        let message2 = try responder.writeMessage()
+        _ = try initiator.readMessage(message2)
+
+        #expect(throws: (any Error).self) {
+            try initiator.writeMessage()
+        }
+    }
+
+    @Test("Responder start handshake is empty and transport ciphers require completion")
+    func responderStartHandshakeAndIncompleteTransportCiphers() throws {
+        let responderSession = NoiseSession(
+            peerID: bobPeerID,
+            role: .responder,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+        let incompleteHandshake = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey
+        )
+
+        #expect(try responderSession.startHandshake().isEmpty)
+        #expect(responderSession.getState() == .handshaking)
+
+        #expect(throws: (any Error).self) {
+            _ = try incompleteHandshake.getTransportCiphers(useExtractedNonce: true)
+        }
+    }
+
+    @Test("Session manager callbacks establish and failed handshakes clean up state")
+    func sessionManagerCallbacksAndFailureCleanup() async throws {
+        let establishedRecorder = SessionCallbackRecorder()
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceStaticKey, keychain: keychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobStaticKey, keychain: keychain)
+
+        aliceManager.onSessionEstablished = establishedRecorder.recordEstablished(peerID:remoteKey:)
+        bobManager.onSessionEstablished = establishedRecorder.recordEstablished(peerID:remoteKey:)
+
+        try establishManagerSessions(aliceManager: aliceManager, bobManager: bobManager)
+
+        let didEstablish = await TestHelpers.waitUntil(
+            { establishedRecorder.establishedCount == 2 },
+            timeout: 0.5
+        )
+        #expect(didEstablish)
+        #expect(establishedRecorder.establishedPeerIDs.contains(alicePeerID))
+        #expect(establishedRecorder.establishedPeerIDs.contains(bobPeerID))
+
+        let failureRecorder = SessionCallbackRecorder()
+        let failingManager = NoiseSessionManager(localStaticKey: charlieStaticKey, keychain: keychain)
+        failingManager.onSessionFailed = failureRecorder.recordFailure(peerID:error:)
+
+        #expect(throws: (any Error).self) {
+            try failingManager.handleIncomingHandshake(
+                from: charliePeerID,
+                message: Data(repeating: 0x00, count: 31)
+            )
+        }
+
+        let didFail = await TestHelpers.waitUntil(
+            { failureRecorder.failureCount == 1 },
+            timeout: 0.5
+        )
+        #expect(didFail)
+        #expect(failingManager.getSession(for: charliePeerID) == nil)
+    }
+
+    @Test("Session manager cleans up initiator sessions after start-handshake failures")
+    func sessionManagerCleansUpInitiatorSessionsAfterStartHandshakeFailures() {
+        let manager = NoiseSessionManager(
+            localStaticKey: aliceStaticKey,
+            keychain: keychain,
+            sessionFactory: { peerID, role in
+                FailingNoiseSession(
+                    peerID: peerID,
+                    role: role,
+                    keychain: self.keychain,
+                    localStaticKey: self.aliceStaticKey
+                )
+            }
+        )
+
+        #expect(throws: FailingNoiseSession.Error.synthetic) {
+            try manager.initiateHandshake(with: alicePeerID)
+        }
+        #expect(manager.getSession(for: alicePeerID) == nil)
+    }
+
+    @Test("Session manager rekeys established sessions and replaces partial handshakes")
+    func sessionManagerRekeysAndReplacesSessions() throws {
+        let manager = NoiseSessionManager(localStaticKey: aliceStaticKey, keychain: keychain)
+
+        #expect(throws: NoiseSessionError.sessionNotFound) {
+            try manager.encrypt(Data("missing".utf8), for: alicePeerID)
+        }
+        #expect(throws: NoiseSessionError.sessionNotFound) {
+            try manager.decrypt(Data("missing".utf8), from: alicePeerID)
+        }
+
+        let initialHandshake = try manager.initiateHandshake(with: alicePeerID)
+        #expect(!initialHandshake.isEmpty)
+        let firstSession = try #require(manager.getSession(for: alicePeerID))
+
+        let restartedHandshake = try manager.initiateHandshake(with: alicePeerID)
+        let restartedSession = try #require(manager.getSession(for: alicePeerID))
+
+        #expect(!restartedHandshake.isEmpty)
+        #expect(restartedSession !== firstSession)
+
+        let restartedInitiator = NoiseSession(
+            peerID: alicePeerID,
+            role: .initiator,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+        let replacementMessage = try restartedInitiator.startHandshake()
+        let replacementResponse = try manager.handleIncomingHandshake(
+            from: alicePeerID,
+            message: replacementMessage
+        )
+        let replacementSession = try #require(manager.getSession(for: alicePeerID))
+
+        #expect(replacementResponse != nil)
+        #expect(replacementSession !== restartedSession)
+
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceStaticKey, keychain: keychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobStaticKey, keychain: keychain)
+        try establishManagerSessions(aliceManager: aliceManager, bobManager: bobManager)
+
+        let establishedSession = try #require(
+            aliceManager.getSession(for: alicePeerID) as? SecureNoiseSession
+        )
+        establishedSession.setMessageCountForTesting(
+            UInt64(Double(NoiseSecurityConstants.maxMessagesPerSession) * 0.9)
+        )
+
+        let sessionsNeedingRekey = aliceManager.getSessionsNeedingRekey()
+        #expect(sessionsNeedingRekey.contains { $0.peerID == alicePeerID && $0.needsRekey })
+
+        #expect(throws: NoiseSessionError.alreadyEstablished) {
+            try aliceManager.initiateHandshake(with: alicePeerID)
+        }
+
+        try aliceManager.initiateRekey(for: alicePeerID)
+        let rekeyedSession = try #require(aliceManager.getSession(for: alicePeerID))
+
+        #expect(rekeyedSession !== establishedSession)
+        #expect(rekeyedSession.getState() == .handshaking)
+    }
+
+    @Test("Secure noise sessions enforce limits and renegotiation thresholds")
+    func secureNoiseSessionsEnforceLimitsAndThresholds() throws {
+        let initiator = SecureNoiseSession(
+            peerID: alicePeerID,
+            role: .initiator,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey
+        )
+        let responder = SecureNoiseSession(
+            peerID: bobPeerID,
+            role: .responder,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        try establishSessions(initiator: initiator, responder: responder)
+
+        responder.setMessageCountForTesting(0)
+        responder.setLastActivityTimeForTesting(Date())
+        #expect(!responder.needsRenegotiation())
+
+        responder.setMessageCountForTesting(
+            UInt64(Double(NoiseSecurityConstants.maxMessagesPerSession) * 0.9)
+        )
+        #expect(responder.needsRenegotiation())
+
+        responder.setMessageCountForTesting(0)
+        responder.setLastActivityTimeForTesting(
+            Date().addingTimeInterval(-(NoiseSecurityConstants.sessionTimeout + 1))
+        )
+        #expect(responder.needsRenegotiation())
+
+        initiator.setMessageCountForTesting(NoiseSecurityConstants.maxMessagesPerSession)
+        #expect(throws: (any Error).self) {
+            try initiator.encrypt(Data("exhausted".utf8))
+        }
+
+        initiator.setMessageCountForTesting(0)
+        #expect(throws: (any Error).self) {
+            try initiator.encrypt(Data(repeating: 0xAB, count: NoiseSecurityConstants.maxMessageSize + 1))
+        }
+
+        responder.setLastActivityTimeForTesting(Date())
+        #expect(throws: (any Error).self) {
+            try responder.decrypt(
+                Data(repeating: 0xCD, count: NoiseSecurityConstants.maxMessageSize + 1)
+            )
+        }
+
+        let transportCiphertext = try initiator.encrypt(Data("secure-session".utf8))
+        #expect(try responder.decrypt(transportCiphertext) == Data("secure-session".utf8))
+    }
+
+    @Test("Secure noise sessions expire based on session start time")
+    func secureNoiseSessionsExpireBasedOnSessionStartTime() throws {
+        let initiator = SecureNoiseSession(
+            peerID: alicePeerID,
+            role: .initiator,
+            keychain: keychain,
+            localStaticKey: aliceStaticKey
+        )
+        let responder = SecureNoiseSession(
+            peerID: bobPeerID,
+            role: .responder,
+            keychain: keychain,
+            localStaticKey: bobStaticKey
+        )
+
+        try establishSessions(initiator: initiator, responder: responder)
+
+        initiator.setSessionStartTimeForTesting(
+            Date().addingTimeInterval(-(NoiseSecurityConstants.sessionTimeout + 1))
+        )
+        #expect(throws: (any Error).self) {
+            try initiator.encrypt(Data("expired".utf8))
+        }
+
+        responder.setSessionStartTimeForTesting(
+            Date().addingTimeInterval(-(NoiseSecurityConstants.sessionTimeout + 1))
+        )
+        #expect(throws: (any Error).self) {
+            try responder.decrypt(Data())
+        }
+    }
+
+    @Test("Rate limiter handles global message caps and per-peer resets")
+    func rateLimiterGlobalMessageCapAndReset() async throws {
+        let globalLimiter = NoiseRateLimiter()
+        for index in 0..<NoiseSecurityConstants.maxGlobalMessagesPerSecond {
+            #expect(globalLimiter.allowMessage(from: PeerID(str: "peer-\(index)")))
+        }
+        #expect(!globalLimiter.allowMessage(from: charliePeerID))
+
+        let peerLimiter = NoiseRateLimiter()
+        for _ in 0..<NoiseSecurityConstants.maxMessagesPerSecond {
+            #expect(peerLimiter.allowMessage(from: alicePeerID))
+        }
+        #expect(!peerLimiter.allowMessage(from: alicePeerID))
+
+        peerLimiter.reset(for: alicePeerID)
+        try await sleep(0.05)
+        #expect(peerLimiter.allowMessage(from: alicePeerID))
+    }
+
+    @Test("Cipher state decrypts high extracted nonces and rejects truncated extracted payloads")
+    func cipherStateDecryptsHighExtractedNoncesAndRejectsTruncatedPayloads() throws {
+        let key = SymmetricKey(size: .bits256)
+        let receiver = NoiseCipherState(key: key, useExtractedNonce: true)
+        let highNoncePayload = try makeExtractedNoncePayload(
+            key: key,
+            nonce: 1_000_000_001,
+            plaintext: Data("high-nonce".utf8)
+        )
+
+        #expect(try receiver.decrypt(ciphertext: highNoncePayload) == Data("high-nonce".utf8))
+        #expect(throws: NoiseError.invalidCiphertext) {
+            try receiver.decrypt(ciphertext: extractedNoncePrefix(7))
+        }
+    }
+
+    private func establishSessions(initiator: NoiseSession, responder: NoiseSession) throws {
+        let message1 = try initiator.startHandshake()
+        let response2 = try responder.processHandshakeMessage(message1)
+        let message2 = try #require(response2)
+        let response3 = try initiator.processHandshakeMessage(message2)
+        let message3 = try #require(response3)
+        let final = try responder.processHandshakeMessage(message3)
+        #expect(final == nil)
+    }
+
+    private func establishManagerSessions(
+        aliceManager: NoiseSessionManager,
+        bobManager: NoiseSessionManager
+    ) throws {
+        let message1 = try aliceManager.initiateHandshake(with: alicePeerID)
+        let response2 = try bobManager.handleIncomingHandshake(from: bobPeerID, message: message1)
+        let message2 = try #require(response2)
+        let response3 = try aliceManager.handleIncomingHandshake(from: alicePeerID, message: message2)
+        let message3 = try #require(response3)
+        let final = try bobManager.handleIncomingHandshake(from: bobPeerID, message: message3)
+        #expect(final == nil)
+    }
+
+    private func makeExtractedNoncePayload(
+        key: SymmetricKey,
+        nonce: UInt64,
+        plaintext: Data,
+        associatedData: Data = Data()
+    ) throws -> Data {
+        var fullNonce = Data(count: 12)
+        withUnsafeBytes(of: nonce.littleEndian) { bytes in
+            fullNonce.replaceSubrange(4..<12, with: bytes)
+        }
+
+        let sealedBox = try ChaChaPoly.seal(
+            plaintext,
+            using: key,
+            nonce: ChaChaPoly.Nonce(data: fullNonce),
+            authenticating: associatedData
+        )
+
+        return extractedNoncePrefix(nonce) + sealedBox.ciphertext + sealedBox.tag
+    }
+
+    private func extractedNoncePrefix(_ nonce: UInt64) -> Data {
+        withUnsafeBytes(of: nonce.bigEndian) { bytes in
+            Data(bytes.suffix(4))
+        }
+    }
+}
+
+private final class SessionCallbackRecorder: @unchecked Sendable {
+    private let lock = NSLock()
+    private var establishedEntries: [(PeerID, Data)] = []
+    private var failureEntries: [(PeerID, String)] = []
+
+    var establishedCount: Int {
+        lock.lock()
+        defer { lock.unlock() }
+        return establishedEntries.count
+    }
+
+    var failureCount: Int {
+        lock.lock()
+        defer { lock.unlock() }
+        return failureEntries.count
+    }
+
+    var establishedPeerIDs: [PeerID] {
+        lock.lock()
+        defer { lock.unlock() }
+        return establishedEntries.map(\.0)
+    }
+
+    func recordEstablished(peerID: PeerID, remoteKey: Curve25519.KeyAgreement.PublicKey) {
+        lock.lock()
+        establishedEntries.append((peerID, remoteKey.rawRepresentation))
+        lock.unlock()
+    }
+
+    func recordFailure(peerID: PeerID, error: Error) {
+        lock.lock()
+        failureEntries.append((peerID, String(describing: error)))
+        lock.unlock()
+    }
+}
+
+private final class FailingNoiseSession: NoiseSession {
+    enum Error: Swift.Error {
+        case synthetic
+    }
+
+    override func startHandshake() throws -> Data {
+        throw Error.synthetic
+    }
+}

localPackages/Noise/Tests/NoiseTests/NoiseEncryptionTests.swift

@@ -0,0 +1,80 @@
+//
+//  NoiseEncryptionTests.swift
+//  Noise
+//
+//  Created by Islam on 14/04/2026.
+//
+
+import Testing
+import BitFoundation
+@testable import Noise
+
+// MARK: - Integration Tests
+
+struct NoiseEncryptionTests {
+    @Test func generatesNewIdentityWhenMissing() throws {
+        let keychain = MockKeychain()
+
+        // Create service with empty keychain - should generate new identity
+        let service = NoiseEncryptionService(keychain: keychain)
+
+        // Should have generated and saved keys
+        #expect(service.getStaticPublicKeyData().count == 32)
+        #expect(service.getSigningPublicKeyData().count == 32)
+
+        // Keys should be persisted
+        let noiseKeyResult = keychain.getIdentityKeyWithResult(forKey: "noiseStaticKey")
+        switch noiseKeyResult {
+        case .success:
+            // Expected - key was saved
+            break
+        default:
+            throw KeychainTestError("Expected noise key to be saved")
+        }
+    }
+
+    @Test func loadsExistingIdentity() throws {
+        let keychain = MockKeychain()
+
+        // Create first service to generate identity
+        let service1 = NoiseEncryptionService(keychain: keychain)
+        let originalPublicKey = service1.getStaticPublicKeyData()
+        let originalSigningKey = service1.getSigningPublicKeyData()
+
+        // Create second service - should load same identity
+        let service2 = NoiseEncryptionService(keychain: keychain)
+
+        #expect(service2.getStaticPublicKeyData() == originalPublicKey)
+        #expect(service2.getSigningPublicKeyData() == originalSigningKey)
+    }
+
+    @Test func handlesAccessDeniedGracefully() throws {
+        let keychain = MockKeychain()
+        keychain.simulatedReadError = .accessDenied
+
+        // Service should still initialize with ephemeral key
+        let service = NoiseEncryptionService(keychain: keychain)
+
+        // Should have an identity (ephemeral)
+        #expect(service.getStaticPublicKeyData().count == 32)
+        #expect(service.getSigningPublicKeyData().count == 32)
+    }
+
+    @Test func handlesDeviceLockedGracefully() throws {
+        let keychain = MockKeychain()
+        keychain.simulatedReadError = .deviceLocked
+
+        // Service should still initialize with ephemeral key
+        let service = NoiseEncryptionService(keychain: keychain)
+
+        // Should have an identity (ephemeral)
+        #expect(service.getStaticPublicKeyData().count == 32)
+    }
+}
+
+// TODO: Reuse
+private struct KeychainTestError: Error, CustomStringConvertible {
+    let message: String
+    init(_ message: String) { self.message = message }
+    var description: String { message }
+}

localPackages/Noise/Tests/NoiseTests/NoiseProtocolTests.swift

@@ -0,0 +1,945 @@
+//
+// NoiseProtocolTests.swift
+// bitchatTests
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import CryptoKit
+import Foundation
+import Testing
+import BitFoundation
+@testable import Noise
+
+// MARK: - Test Vector Support
+
+struct NoiseTestVector: Codable {
+    let protocol_name: String
+    let init_prologue: String
+    let init_static: String
+    let init_ephemeral: String
+    let init_psks: [String]?
+    let resp_prologue: String
+    let resp_static: String
+    let resp_ephemeral: String
+    let resp_psks: [String]?
+    let handshake_hash: String?
+    let messages: [TestMessage]
+    
+    struct TestMessage: Codable {
+        let payload: String
+        let ciphertext: String
+    }
+}
+
+extension Data {
+    init?(hex: String) {
+        let cleaned = hex.replacingOccurrences(of: " ", with: "")
+        guard cleaned.count % 2 == 0 else { return nil }
+        var data = Data(capacity: cleaned.count / 2)
+        var index = cleaned.startIndex
+        while index < cleaned.endIndex {
+            let nextIndex = cleaned.index(index, offsetBy: 2)
+            guard let byte = UInt8(cleaned[index..<nextIndex], radix: 16) else { return nil }
+            data.append(byte)
+            index = nextIndex
+        }
+        self = data
+    }
+    
+    func hexString() -> String {
+        map { String(format: "%02x", $0) }.joined()
+    }
+}
+
+struct NoiseProtocolTests {
+    
+    private let aliceKey = Curve25519.KeyAgreement.PrivateKey()
+    private let bobKey = Curve25519.KeyAgreement.PrivateKey()
+    private let mockKeychain = MockKeychain()
+    
+    private let alicePeerID = PeerID(str: UUID().uuidString)
+    private let bobPeerID = PeerID(str: UUID().uuidString)
+    
+    private let aliceSession: NoiseSession
+    private let bobSession: NoiseSession
+    
+    init() {
+        aliceSession = NoiseSession(
+            peerID: alicePeerID,
+            role: .initiator,
+            keychain: mockKeychain,
+            localStaticKey: aliceKey
+        )
+        
+        bobSession = NoiseSession(
+            peerID: bobPeerID,
+            role: .responder,
+            keychain: mockKeychain,
+            localStaticKey: bobKey
+        )
+    }
+    
+    // MARK: - Basic Handshake Tests
+    
+    @Test func xxPatternHandshake() throws {
+        // Alice starts handshake (message 1)
+        let message1 = try aliceSession.startHandshake()
+        #expect(!message1.isEmpty)
+        #expect(aliceSession.getState() == .handshaking)
+        
+        // Bob processes message 1 and creates message 2
+        let message2 = try bobSession.processHandshakeMessage(message1)
+        #expect(message2 != nil)
+        #expect(!message2!.isEmpty)
+        #expect(bobSession.getState() == .handshaking)
+        
+        // Alice processes message 2 and creates message 3
+        let message3 = try aliceSession.processHandshakeMessage(message2!)
+        #expect(message3 != nil)
+        #expect(!message3!.isEmpty)
+        #expect(aliceSession.getState() == .established)
+        
+        // Bob processes message 3 and completes handshake
+        let finalMessage = try bobSession.processHandshakeMessage(message3!)
+        #expect(finalMessage == nil)  // No more messages needed
+        #expect(bobSession.getState() == .established)
+        
+        // Verify both sessions are established
+        #expect(aliceSession.isEstablished())
+        #expect(bobSession.isEstablished())
+        
+        // Verify they have each other's static keys
+        #expect(
+            aliceSession.getRemoteStaticPublicKey()?.rawRepresentation
+            == bobKey.publicKey.rawRepresentation)
+        #expect(
+            bobSession.getRemoteStaticPublicKey()?.rawRepresentation
+            == aliceKey.publicKey.rawRepresentation)
+    }
+    
+    @Test func handshakeStateValidation() throws {
+        // Cannot process message before starting handshake
+        #expect(throws: NoiseSessionError.invalidState) {
+            try aliceSession.processHandshakeMessage(Data())
+        }
+        
+        // Start handshake
+        _ = try aliceSession.startHandshake()
+        
+        // Cannot start handshake twice
+        #expect(throws: NoiseSessionError.invalidState) {
+            try aliceSession.startHandshake()
+        }
+    }
+    
+    // MARK: - Encryption/Decryption Tests
+    
+    @Test func basicEncryptionDecryption() throws {
+        try performHandshake(initiator: aliceSession, responder: bobSession)
+        
+        let plaintext = "Hello, Bob!".data(using: .utf8)!
+        
+        // Alice encrypts
+        let ciphertext = try aliceSession.encrypt(plaintext)
+        #expect(ciphertext != plaintext)
+        #expect(ciphertext.count > plaintext.count)  // Should have overhead
+        
+        // Bob decrypts
+        let decrypted = try bobSession.decrypt(ciphertext)
+        #expect(decrypted == plaintext)
+    }
+    
+    @Test func bidirectionalEncryption() throws {
+        try performHandshake(initiator: aliceSession, responder: bobSession)
+        
+        // Alice -> Bob
+        let aliceMessage = "Hello from Alice".data(using: .utf8)!
+        let aliceCiphertext = try aliceSession.encrypt(aliceMessage)
+        let bobReceived = try bobSession.decrypt(aliceCiphertext)
+        #expect(bobReceived == aliceMessage)
+        
+        // Bob -> Alice
+        let bobMessage = "Hello from Bob".data(using: .utf8)!
+        let bobCiphertext = try bobSession.encrypt(bobMessage)
+        let aliceReceived = try aliceSession.decrypt(bobCiphertext)
+        #expect(aliceReceived == bobMessage)
+    }
+    
+    @Test func largeMessageEncryption() throws {
+        try performHandshake(initiator: aliceSession, responder: bobSession)
+        
+        // Create a large message
+        let largeMessage = TestHelpers.generateRandomData(length: 100_000)
+        
+        // Encrypt and decrypt
+        let ciphertext = try aliceSession.encrypt(largeMessage)
+        let decrypted = try bobSession.decrypt(ciphertext)
+        
+        #expect(decrypted == largeMessage)
+    }
+    
+    @Test func encryptionBeforeHandshake() {
+        let plaintext = "test".data(using: .utf8)!
+        
+        #expect(throws: NoiseSessionError.notEstablished) {
+            try aliceSession.encrypt(plaintext)
+        }
+        
+        #expect(throws: NoiseSessionError.notEstablished) {
+            try aliceSession.decrypt(plaintext)
+        }
+    }
+    
+    // MARK: - Session Manager Tests
+    
+    @Test func sessionManagerBasicOperations() throws {
+        let manager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        
+        #expect(manager.getSession(for: alicePeerID) == nil)
+        
+        _ = try manager.initiateHandshake(with: alicePeerID)
+        #expect(manager.getSession(for: alicePeerID) != nil)
+        
+        // Get session
+        let retrieved = manager.getSession(for: alicePeerID)
+        #expect(retrieved != nil)
+        
+        // Remove session
+        manager.removeSession(for: alicePeerID)
+        #expect(manager.getSession(for: alicePeerID) == nil)
+    }
+    
+    @Test func sessionManagerHandshakeInitiation() throws {
+        let manager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        
+        // Initiate handshake
+        let handshakeData = try manager.initiateHandshake(with: alicePeerID)
+        #expect(!handshakeData.isEmpty)
+        
+        // Session should exist
+        let session = manager.getSession(for: alicePeerID)
+        #expect(session != nil)
+        #expect(session?.getState() == .handshaking)
+    }
+    
+    @Test func sessionManagerIncomingHandshake() throws {
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobKey, keychain: mockKeychain)
+        
+        // Alice initiates
+        let message1 = try aliceManager.initiateHandshake(with: alicePeerID)
+        
+        // Bob responds
+        let message2 = try bobManager.handleIncomingHandshake(from: bobPeerID, message: message1)
+        #expect(message2 != nil)
+        
+        // Continue handshake
+        let message3 = try aliceManager.handleIncomingHandshake(
+            from: alicePeerID, message: message2!)
+        #expect(message3 != nil)
+        
+        // Complete handshake
+        let finalMessage = try bobManager.handleIncomingHandshake(
+            from: bobPeerID, message: message3!)
+        #expect(finalMessage == nil)
+        
+        // Both should have established sessions
+        #expect(aliceManager.getSession(for: alicePeerID)?.isEstablished() == true)
+        #expect(bobManager.getSession(for: bobPeerID)?.isEstablished() == true)
+    }
+    
+    @Test func sessionManagerEncryptionDecryption() throws {
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobKey, keychain: mockKeychain)
+        
+        // Establish sessions
+        try establishManagerSessions(aliceManager: aliceManager, bobManager: bobManager)
+        
+        // Encrypt with manager
+        let plaintext = "Test message".data(using: .utf8)!
+        let ciphertext = try aliceManager.encrypt(plaintext, for: alicePeerID)
+        
+        // Decrypt with manager
+        let decrypted = try bobManager.decrypt(ciphertext, from: bobPeerID)
+        #expect(decrypted == plaintext)
+    }
+    
+    // MARK: - Security Tests
+    
+    @Test func tamperedCiphertextDetection() throws {
+        try performHandshake(initiator: aliceSession, responder: bobSession)
+        
+        let plaintext = "Secret message".data(using: .utf8)!
+        var ciphertext = try aliceSession.encrypt(plaintext)
+        
+        // Tamper with ciphertext
+        ciphertext[ciphertext.count / 2] ^= 0xFF
+        
+        // Decryption should fail
+        if #available(macOS 14.4, iOS 17.4, *) {
+            #expect(throws: CryptoKitError.authenticationFailure) {
+                try bobSession.decrypt(ciphertext)
+            }
+        } else {
+            #expect(throws: (any Error).self) {
+                try bobSession.decrypt(ciphertext)
+            }
+        }
+    }
+    
+    @Test func replayPrevention() throws {
+        try performHandshake(initiator: aliceSession, responder: bobSession)
+        
+        let plaintext = "Test message".data(using: .utf8)!
+        let ciphertext = try aliceSession.encrypt(plaintext)
+        
+        // First decryption should succeed
+        _ = try bobSession.decrypt(ciphertext)
+        
+        // Replaying the same ciphertext should fail
+        #expect(throws: NoiseError.replayDetected) {
+            try bobSession.decrypt(ciphertext)
+        }
+    }
+    
+    @Test func sessionIsolation() throws {
+        // Create two separate session pairs
+        let aliceSession1 = NoiseSession(
+            peerID: PeerID(str: "peer1"), role: .initiator, keychain: mockKeychain,
+            localStaticKey: aliceKey)
+        let bobSession1 = NoiseSession(
+            peerID: PeerID(str: "alice1"), role: .responder, keychain: mockKeychain,
+            localStaticKey: bobKey)
+        
+        let aliceSession2 = NoiseSession(
+            peerID: PeerID(str: "peer2"), role: .initiator, keychain: mockKeychain,
+            localStaticKey: aliceKey)
+        let bobSession2 = NoiseSession(
+            peerID: PeerID(str: "alice2"), role: .responder, keychain: mockKeychain,
+            localStaticKey: bobKey)
+        
+        // Establish both pairs
+        try performHandshake(initiator: aliceSession1, responder: bobSession1)
+        try performHandshake(initiator: aliceSession2, responder: bobSession2)
+        
+        // Encrypt with session 1
+        let plaintext = "Secret".data(using: .utf8)!
+        let ciphertext1 = try aliceSession1.encrypt(plaintext)
+        
+        // Should not be able to decrypt with session 2
+        if #available(macOS 14.4, iOS 17.4, *) {
+            #expect(throws: CryptoKitError.authenticationFailure) {
+                try bobSession2.decrypt(ciphertext1)
+            }
+        } else {
+            #expect(throws: (any Error).self) {
+                try bobSession2.decrypt(ciphertext1)
+            }
+        }
+        
+        // But should work with correct session
+        let decrypted = try bobSession1.decrypt(ciphertext1)
+        #expect(decrypted == plaintext)
+    }
+    
+    // MARK: - Session Recovery Tests
+    
+    @Test func peerRestartDetection() throws {
+        // Establish initial sessions
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobKey, keychain: mockKeychain)
+        
+        try establishManagerSessions(aliceManager: aliceManager, bobManager: bobManager)
+        
+        // Exchange some messages to establish nonce state
+        let message1 = try aliceManager.encrypt("Hello".data(using: .utf8)!, for: alicePeerID)
+        _ = try bobManager.decrypt(message1, from: bobPeerID)
+        
+        let message2 = try bobManager.encrypt("World".data(using: .utf8)!, for: bobPeerID)
+        _ = try aliceManager.decrypt(message2, from: alicePeerID)
+        
+        // Simulate Bob restart by creating new manager with same key
+        let bobManagerRestarted = NoiseSessionManager(
+            localStaticKey: bobKey, keychain: mockKeychain)
+        
+        // Bob initiates new handshake after restart
+        let newHandshake1 = try bobManagerRestarted.initiateHandshake(with: bobPeerID)
+        
+        // Alice should accept the new handshake (clearing old session)
+        let newHandshake2 = try aliceManager.handleIncomingHandshake(
+            from: alicePeerID, message: newHandshake1)
+        #expect(newHandshake2 != nil)
+        
+        // Complete the new handshake
+        let newHandshake3 = try bobManagerRestarted.handleIncomingHandshake(
+            from: bobPeerID, message: newHandshake2!)
+        #expect(newHandshake3 != nil)
+        _ = try aliceManager.handleIncomingHandshake(from: alicePeerID, message: newHandshake3!)
+        
+        // Should be able to exchange messages with new sessions
+        let testMessage = "After restart".data(using: .utf8)!
+        let encrypted = try bobManagerRestarted.encrypt(testMessage, for: bobPeerID)
+        let decrypted = try aliceManager.decrypt(encrypted, from: alicePeerID)
+        #expect(decrypted == testMessage)
+    }
+    
+    @Test func nonceDesynchronizationRecovery() throws {
+        // Create two sessions
+        let aliceSession = NoiseSession(
+            peerID: alicePeerID, role: .initiator, keychain: mockKeychain, localStaticKey: aliceKey)
+        let bobSession = NoiseSession(
+            peerID: bobPeerID, role: .responder, keychain: mockKeychain, localStaticKey: bobKey)
+        
+        // Establish sessions
+        try performHandshake(initiator: aliceSession, responder: bobSession)
+        
+        // Exchange messages to advance nonces
+        for i in 0..<5 {
+            let msg = try aliceSession.encrypt("Message \(i)".data(using: .utf8)!)
+            _ = try bobSession.decrypt(msg)
+        }
+        
+        // Simulate desynchronization by encrypting but not decrypting
+        for i in 0..<3 {
+            _ = try aliceSession.encrypt("Lost message \(i)".data(using: .utf8)!)
+        }
+        
+        // With per-packet nonce carried, decryption should not throw here
+        let desyncMessage = try aliceSession.encrypt("This now succeeds".data(using: .utf8)!)
+        #expect(throws: Never.self) {
+            try bobSession.decrypt(desyncMessage)
+        }
+    }
+    
+    @Test func concurrentEncryption() async throws {
+        // Test thread safety of encryption operations
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobKey, keychain: mockKeychain)
+        
+        try establishManagerSessions(aliceManager: aliceManager, bobManager: bobManager)
+        
+        let messageCount = 100
+        
+        try await confirmation("All messages encrypted and decrypted", expectedCount: messageCount)
+        { completion in
+            var encryptedMessages: [Int: Data] = [:]
+            // Encrypt messages sequentially to avoid nonce races in manager
+            for i in 0..<messageCount {
+                let plaintext = "Concurrent message \(i)".data(using: .utf8)!
+                let encrypted = try aliceManager.encrypt(plaintext, for: alicePeerID)
+                encryptedMessages[i] = encrypted
+            }
+            
+            // Decrypt messages sequentially to avoid triggering anti-replay with reordering
+            for i in 0..<messageCount {
+                do {
+                    guard let encrypted = encryptedMessages[i] else {
+                        Issue.record("Missing encrypted message \(i)")
+                        return
+                    }
+                    let decrypted = try bobManager.decrypt(encrypted, from: bobPeerID)
+                    let expected = "Concurrent message \(i)".data(using: .utf8)!
+                    #expect(decrypted == expected)
+                    completion()
+                } catch {
+                    Issue.record("Decryption failed for message \(i): \(error)")
+                }
+            }
+        }
+    }
+    
+    @Test func sessionStaleDetection() throws {
+        // Test that sessions are properly marked as stale
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobKey, keychain: mockKeychain)
+        
+        try establishManagerSessions(aliceManager: aliceManager, bobManager: bobManager)
+        
+        // Get the session and check it needs renegotiation based on age
+        let sessions = aliceManager.getSessionsNeedingRekey()
+        
+        // New session should not need rekey
+        #expect(sessions.isEmpty || sessions.allSatisfy { !$0.needsRekey })
+    }
+    
+    @Test func handshakeAfterDecryptionFailure() throws {
+        // Test that handshake is properly initiated after decryption failure
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobKey, keychain: mockKeychain)
+        
+        // Establish sessions
+        try establishManagerSessions(aliceManager: aliceManager, bobManager: bobManager)
+        
+        // Create a corrupted message
+        var encrypted = try aliceManager.encrypt("Test".data(using: .utf8)!, for: alicePeerID)
+        encrypted[10] ^= 0xFF  // Corrupt the data
+        
+        // Decryption should fail
+        if #available(macOS 14.4, iOS 17.4, *) {
+            #expect(throws: CryptoKitError.authenticationFailure) {
+                try bobManager.decrypt(encrypted, from: bobPeerID)
+            }
+        } else {
+            #expect(throws: (any Error).self) {
+                try bobManager.decrypt(encrypted, from: bobPeerID)
+            }
+        }
+        
+        // Bob should still have the session (it's not removed on single failure)
+        #expect(bobManager.getSession(for: bobPeerID) != nil)
+    }
+    
+    @Test func handshakeAlwaysAcceptedWithExistingSession() throws {
+        // Test that handshake is always accepted even with existing valid session
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobKey, keychain: mockKeychain)
+        
+        // Establish sessions
+        try establishManagerSessions(aliceManager: aliceManager, bobManager: bobManager)
+        
+        // Verify sessions are established
+        #expect(aliceManager.getSession(for: alicePeerID)?.isEstablished() == true)
+        #expect(bobManager.getSession(for: bobPeerID)?.isEstablished() == true)
+        
+        // Exchange messages to verify sessions work
+        let testMessage = "Session works".data(using: .utf8)!
+        let encrypted = try aliceManager.encrypt(testMessage, for: alicePeerID)
+        let decrypted = try bobManager.decrypt(encrypted, from: bobPeerID)
+        #expect(decrypted == testMessage)
+        
+        // Alice clears her session (simulating decryption failure)
+        aliceManager.removeSession(for: alicePeerID)
+        
+        // Alice initiates new handshake despite Bob having valid session
+        let newHandshake1 = try aliceManager.initiateHandshake(with: alicePeerID)
+        
+        // Bob should accept the new handshake even though he has a valid session
+        let newHandshake2 = try bobManager.handleIncomingHandshake(
+            from: bobPeerID, message: newHandshake1)
+        #expect(newHandshake2 != nil, "Bob should accept handshake despite having valid session")
+        
+        // Complete the handshake
+        let newHandshake3 = try aliceManager.handleIncomingHandshake(
+            from: alicePeerID, message: newHandshake2!)
+        #expect(newHandshake3 != nil)
+        _ = try bobManager.handleIncomingHandshake(from: bobPeerID, message: newHandshake3!)
+        
+        // Verify new sessions work
+        let testMessage2 = "New session works".data(using: .utf8)!
+        let encrypted2 = try aliceManager.encrypt(testMessage2, for: alicePeerID)
+        let decrypted2 = try bobManager.decrypt(encrypted2, from: bobPeerID)
+        #expect(decrypted2 == testMessage2)
+    }
+    
+    @Test func nonceDesynchronizationCausesRehandshake() throws {
+        // Test that nonce desynchronization leads to proper re-handshake
+        let aliceManager = NoiseSessionManager(localStaticKey: aliceKey, keychain: mockKeychain)
+        let bobManager = NoiseSessionManager(localStaticKey: bobKey, keychain: mockKeychain)
+        
+        // Establish sessions
+        try establishManagerSessions(aliceManager: aliceManager, bobManager: bobManager)
+        
+        // Exchange messages normally
+        for i in 0..<5 {
+            let msg = try aliceManager.encrypt("Message \(i)".data(using: .utf8)!, for: alicePeerID)
+            _ = try bobManager.decrypt(msg, from: bobPeerID)
+        }
+        
+        // Simulate desynchronization - Alice sends messages that Bob doesn't receive
+        for i in 0..<3 {
+            _ = try aliceManager.encrypt("Lost message \(i)".data(using: .utf8)!, for: alicePeerID)
+        }
+        
+        // With nonce carried in packet, decryption should not throw here
+        let desyncMessage = try aliceManager.encrypt(
+            "This now succeeds".data(using: .utf8)!, for: alicePeerID)
+        #expect(throws: Never.self) {
+            try bobManager.decrypt(desyncMessage, from: bobPeerID)
+        }
+        
+        // Bob clears session and initiates new handshake
+        bobManager.removeSession(for: bobPeerID)
+        let rehandshake1 = try bobManager.initiateHandshake(with: bobPeerID)
+        
+        // Alice should accept despite having a "valid" (but desynced) session
+        let rehandshake2 = try aliceManager.handleIncomingHandshake(
+            from: alicePeerID, message: rehandshake1)
+        #expect(rehandshake2 != nil, "Alice should accept handshake to fix desync")
+        
+        // Complete handshake
+        let rehandshake3 = try bobManager.handleIncomingHandshake(
+            from: bobPeerID, message: rehandshake2!)
+        #expect(rehandshake3 != nil)
+        _ = try aliceManager.handleIncomingHandshake(from: alicePeerID, message: rehandshake3!)
+        
+        // Verify communication works again
+        let testResynced = "Resynced".data(using: .utf8)!
+        let encryptedResync = try aliceManager.encrypt(testResynced, for: alicePeerID)
+        let decryptedResync = try bobManager.decrypt(encryptedResync, from: bobPeerID)
+        #expect(decryptedResync == testResynced)
+    }
+    
+    // MARK: - Test Vector Tests
+    
+    @Test func noiseTestVectors() throws {
+        // Load test vectors from bundle
+        let testVectors = try loadTestVectors()
+        
+        for (index, testVector) in testVectors.enumerated() {
+            print("Running test vector \(index + 1): \(testVector.protocol_name)")
+            try runTestVector(testVector)
+        }
+    }
+    
+    // MARK: - Helper Methods
+    
+    private func performHandshake(initiator: NoiseSession, responder: NoiseSession) throws {
+        let msg1 = try initiator.startHandshake()
+        let msg2 = try responder.processHandshakeMessage(msg1)!
+        let msg3 = try initiator.processHandshakeMessage(msg2)!
+        _ = try responder.processHandshakeMessage(msg3)
+    }
+    
+    private func establishManagerSessions(
+        aliceManager: NoiseSessionManager, bobManager: NoiseSessionManager
+    ) throws {
+        let msg1 = try aliceManager.initiateHandshake(with: alicePeerID)
+        let msg2 = try bobManager.handleIncomingHandshake(from: bobPeerID, message: msg1)!
+        let msg3 = try aliceManager.handleIncomingHandshake(from: alicePeerID, message: msg2)!
+        _ = try bobManager.handleIncomingHandshake(from: bobPeerID, message: msg3)
+    }
+    
+    private func loadTestVectors() throws -> [NoiseTestVector] {
+        // Try to load from test bundle
+        guard let url = Bundle.module.url(forResource: "NoiseTestVectors", withExtension: "json") else {
+            throw NSError(
+                domain: "NoiseTests", code: 1,
+                userInfo: [
+                    NSLocalizedDescriptionKey: "Could not find NoiseTestVectors.json in test bundle"
+                ])
+        }
+        
+        let data = try Data(contentsOf: url)
+        return try JSONDecoder().decode([NoiseTestVector].self, from: data)
+    }
+    
+    private func runTestVector(_ testVector: NoiseTestVector) throws {
+        // Parse test inputs
+        guard let initStatic = Data(hex: testVector.init_static),
+              let initEphemeral = Data(hex: testVector.init_ephemeral),
+              let respStatic = Data(hex: testVector.resp_static),
+              let respEphemeral = Data(hex: testVector.resp_ephemeral),
+              let prologue = Data(hex: testVector.init_prologue)
+        else {
+            throw NSError(
+                domain: "NoiseTests", code: 2,
+                userInfo: [NSLocalizedDescriptionKey: "Failed to parse test vector hex strings"])
+        }
+        
+        let expectedHash = testVector.handshake_hash.flatMap { Data(hex: $0) }
+        
+        // Create keys
+        guard
+            let initStaticKey = try? Curve25519.KeyAgreement.PrivateKey(
+                rawRepresentation: initStatic),
+            let initEphemeralKey = try? Curve25519.KeyAgreement.PrivateKey(
+                rawRepresentation: initEphemeral),
+            let respStaticKey = try? Curve25519.KeyAgreement.PrivateKey(
+                rawRepresentation: respStatic),
+            let respEphemeralKey = try? Curve25519.KeyAgreement.PrivateKey(
+                rawRepresentation: respEphemeral)
+        else {
+            throw NSError(
+                domain: "NoiseTests", code: 3,
+                userInfo: [NSLocalizedDescriptionKey: "Failed to create keys from test vectors"])
+        }
+        
+        let keychain = MockKeychain()
+        
+        // Create handshake states
+        let initiatorHandshake = NoiseHandshakeState(
+            role: .initiator,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: initStaticKey,
+            prologue: prologue,
+            predeterminedEphemeralKey: initEphemeralKey
+        )
+        
+        let responderHandshake = NoiseHandshakeState(
+            role: .responder,
+            pattern: .XX,
+            keychain: keychain,
+            localStaticKey: respStaticKey,
+            prologue: prologue,
+            predeterminedEphemeralKey: respEphemeralKey
+        )
+        
+        // For XX pattern, we have 3 handshake messages, then transport messages
+        // The test vector messages are ordered as: [msg1, msg2, msg3, transport1, transport2, ...]
+        
+        guard testVector.messages.count >= 3 else {
+            throw NSError(
+                domain: "NoiseTests", code: 5,
+                userInfo: [NSLocalizedDescriptionKey: "Test vector must have at least 3 messages for XX pattern"])
+        }
+        
+        // Message 1: Initiator -> Responder (e)
+        guard let payload1 = Data(hex: testVector.messages[0].payload),
+              let expectedCiphertext1 = Data(hex: testVector.messages[0].ciphertext) else {
+            throw NSError(
+                domain: "NoiseTests", code: 4,
+                userInfo: [NSLocalizedDescriptionKey: "Message 1: Failed to parse hex"])
+        }
+        
+        let msg1 = try initiatorHandshake.writeMessage(payload: payload1)
+        #expect(!msg1.isEmpty, "Message 1 should not be empty")
+        #expect(msg1 == expectedCiphertext1, "Message 1 ciphertext should match expected value. Got: \(msg1.hexString()), Expected: \(expectedCiphertext1.hexString())")
+        
+        let decrypted1 = try responderHandshake.readMessage(msg1)
+        #expect(decrypted1 == payload1, "Message 1: Decrypted payload should match original")
+        
+        // Message 2: Responder -> Initiator (e, ee, s, es)
+        guard let payload2 = Data(hex: testVector.messages[1].payload),
+              let expectedCiphertext2 = Data(hex: testVector.messages[1].ciphertext) else {
+            throw NSError(
+                domain: "NoiseTests", code: 4,
+                userInfo: [NSLocalizedDescriptionKey: "Message 2: Failed to parse hex"])
+        }
+        
+        let msg2 = try responderHandshake.writeMessage(payload: payload2)
+        #expect(!msg2.isEmpty, "Message 2 should not be empty")
+        #expect(msg2 == expectedCiphertext2, "Message 2 ciphertext should match expected value. Got: \(msg2.hexString()), Expected: \(expectedCiphertext2.hexString())")
+        
+        let decrypted2 = try initiatorHandshake.readMessage(msg2)
+        #expect(decrypted2 == payload2, "Message 2: Decrypted payload should match original")
+        
+        // Message 3: Initiator -> Responder (s, se)
+        guard let payload3 = Data(hex: testVector.messages[2].payload),
+              let expectedCiphertext3 = Data(hex: testVector.messages[2].ciphertext) else {
+            throw NSError(
+                domain: "NoiseTests", code: 4,
+                userInfo: [NSLocalizedDescriptionKey: "Message 3: Failed to parse hex"])
+        }
+        
+        let msg3 = try initiatorHandshake.writeMessage(payload: payload3)
+        #expect(!msg3.isEmpty, "Message 3 should not be empty")
+        #expect(msg3 == expectedCiphertext3, "Message 3 ciphertext should match expected value. Got: \(msg3.hexString()), Expected: \(expectedCiphertext3.hexString())")
+        
+        let decrypted3 = try responderHandshake.readMessage(msg3)
+        #expect(decrypted3 == payload3, "Message 3: Decrypted payload should match original")
+        
+        // Verify handshake hash
+        let initiatorHash = initiatorHandshake.getHandshakeHash()
+        let responderHash = responderHandshake.getHandshakeHash()
+        
+        #expect(initiatorHash == responderHash, "Initiator and responder hashes should match")
+        
+        if let expectedHash = expectedHash {
+            #expect(
+                initiatorHash == expectedHash,
+                "Handshake hash should match expected value from test vector. Got: \(initiatorHash.hexString()), Expected: \(expectedHash.hexString())")
+        }
+        
+        // Get transport ciphers
+        let (initSend, initRecv, _) = try initiatorHandshake.getTransportCiphers(useExtractedNonce: false)
+        let (respSend, respRecv, _) = try responderHandshake.getTransportCiphers(useExtractedNonce: false)
+
+        // Test transport messages (messages after the 3 handshake messages)
+        for index in 3..<testVector.messages.count {
+            let testMsg = testVector.messages[index]
+            guard let payload = Data(hex: testMsg.payload),
+                  let expectedCiphertext = Data(hex: testMsg.ciphertext) else {
+                throw NSError(
+                    domain: "NoiseTests", code: 4,
+                    userInfo: [
+                        NSLocalizedDescriptionKey:
+                            "Message \(index + 1): Failed to parse payload hex"
+                    ])
+            }
+            
+            // Alternate between responder and initiator sending
+            // Responder sends first transport message (since initiator sent last handshake message)
+            let (sender, receiver): (NoiseCipherState, NoiseCipherState)
+            let transportIndex = index - 3
+            if transportIndex % 2 == 0 {
+                // Even transport messages: responder sends
+                sender = respSend
+                receiver = initRecv
+            } else {
+                // Odd transport messages: initiator sends
+                sender = initSend
+                receiver = respRecv
+            }
+            
+            // Encrypt and validate ciphertext matches expected value
+            let ciphertext = try sender.encrypt(plaintext: payload)
+            #expect(
+                ciphertext == expectedCiphertext,
+                "Message \(index + 1) ciphertext should match expected value. Got: \(ciphertext.hexString()), Expected: \(expectedCiphertext.hexString())")
+
+            // Decrypt and validate payload
+            let decrypted = try receiver.decrypt(ciphertext: ciphertext)
+            #expect(
+                decrypted == payload,
+                "Message \(index + 1): Decrypted payload should match original")
+        }
+    }
+
+    // MARK: - DH Shared Secret Clearing Tests
+
+    @Test func secureClearCalledDuringHandshake() throws {
+        // Use TrackingMockKeychain to verify secureClear is called
+        let trackingKeychain = TrackingMockKeychain()
+
+        let aliceKey = Curve25519.KeyAgreement.PrivateKey()
+        let bobKey = Curve25519.KeyAgreement.PrivateKey()
+
+        let alice = NoiseSession(
+            peerID: PeerID(str: "alice-test"),
+            role: .initiator,
+            keychain: trackingKeychain,
+            localStaticKey: aliceKey
+        )
+
+        let bob = NoiseSession(
+            peerID: PeerID(str: "bob-test"),
+            role: .responder,
+            keychain: trackingKeychain,
+            localStaticKey: bobKey
+        )
+
+        // Perform handshake
+        let msg1 = try alice.startHandshake()
+        let msg2 = try bob.processHandshakeMessage(msg1)!
+        let msg3 = try alice.processHandshakeMessage(msg2)!
+        _ = try bob.processHandshakeMessage(msg3)
+
+        // In Noise XX pattern handshake:
+        // - Message 1 (initiator): e token only (no DH)
+        // - Message 2 (responder): e, ee, s, es tokens (2 DH operations: ee, es)
+        // - Message 3 (initiator): s, se tokens (1 DH operation: se)
+        // Total in writeMessage: 3 DH operations (ee, es, se)
+        //
+        // In readMessage (performDHOperation):
+        // - After msg1: no DH
+        // - After msg2: ee, es (2 DH operations)
+        // - After msg3: se (1 DH operation)
+        // Total in performDHOperation: 3 DH operations
+        //
+        // Grand total: 6 DH operations requiring secureClear
+        //
+        // Note: .ss pattern is only used in certain handshake patterns, not XX
+        let expectedMinimumCalls = 6
+        #expect(
+            trackingKeychain.secureClearDataCallCount >= expectedMinimumCalls,
+            "Expected at least \(expectedMinimumCalls) secureClear calls for DH secrets, got \(trackingKeychain.secureClearDataCallCount)"
+        )
+    }
+
+    @Test func encryptionWorksAfterSecureClear() throws {
+        // Verify that encryption/decryption still works correctly after adding secureClear
+        let trackingKeychain = TrackingMockKeychain()
+
+        let aliceKey = Curve25519.KeyAgreement.PrivateKey()
+        let bobKey = Curve25519.KeyAgreement.PrivateKey()
+
+        let alice = NoiseSession(
+            peerID: PeerID(str: "alice-test-enc"),
+            role: .initiator,
+            keychain: trackingKeychain,
+            localStaticKey: aliceKey
+        )
+
+        let bob = NoiseSession(
+            peerID: PeerID(str: "bob-test-enc"),
+            role: .responder,
+            keychain: trackingKeychain,
+            localStaticKey: bobKey
+        )
+
+        // Perform handshake
+        let msg1 = try alice.startHandshake()
+        let msg2 = try bob.processHandshakeMessage(msg1)!
+        let msg3 = try alice.processHandshakeMessage(msg2)!
+        _ = try bob.processHandshakeMessage(msg3)
+
+        // Verify both sessions are established
+        #expect(alice.isEstablished())
+        #expect(bob.isEstablished())
+
+        // Verify secureClear was called (basic sanity check)
+        #expect(trackingKeychain.secureClearDataCallCount > 0)
+
+        // Test encryption from Alice to Bob
+        let plaintext1 = "Hello from Alice after secureClear!".data(using: .utf8)!
+        let ciphertext1 = try alice.encrypt(plaintext1)
+        let decrypted1 = try bob.decrypt(ciphertext1)
+        #expect(decrypted1 == plaintext1)
+
+        // Test encryption from Bob to Alice
+        let plaintext2 = "Hello from Bob after secureClear!".data(using: .utf8)!
+        let ciphertext2 = try bob.encrypt(plaintext2)
+        let decrypted2 = try alice.decrypt(ciphertext2)
+        #expect(decrypted2 == plaintext2)
+
+        // Test multiple messages to verify cipher state is correct
+        for i in 1...10 {
+            let msg = "Message \(i) from Alice".data(using: .utf8)!
+            let cipher = try alice.encrypt(msg)
+            let dec = try bob.decrypt(cipher)
+            #expect(dec == msg)
+        }
+    }
+
+    @Test func secureClearCalledInBothWriteAndReadPaths() throws {
+        // Verify secureClear is called in both writeMessage and readMessage paths
+        // We do this by checking the count increases at each step
+
+        let aliceKeychain = TrackingMockKeychain()
+        let bobKeychain = TrackingMockKeychain()
+
+        let aliceKey = Curve25519.KeyAgreement.PrivateKey()
+        let bobKey = Curve25519.KeyAgreement.PrivateKey()
+
+        let alice = NoiseSession(
+            peerID: PeerID(str: "alice-paths"),
+            role: .initiator,
+            keychain: aliceKeychain,
+            localStaticKey: aliceKey
+        )
+
+        let bob = NoiseSession(
+            peerID: PeerID(str: "bob-paths"),
+            role: .responder,
+            keychain: bobKeychain,
+            localStaticKey: bobKey
+        )
+
+        // Message 1: Alice writes (e token only, no DH)
+        let msg1 = try alice.startHandshake()
+        let aliceCountAfterMsg1 = aliceKeychain.secureClearDataCallCount
+        // No DH in message 1 for initiator
+        #expect(aliceCountAfterMsg1 == 0, "No DH secrets in message 1 write")
+
+        // Bob reads message 1 (no DH) and writes message 2 (ee, es DH operations)
+        let msg2 = try bob.processHandshakeMessage(msg1)!
+        let bobCountAfterMsg2 = bobKeychain.secureClearDataCallCount
+        // Bob should have cleared secrets for: ee (read), es (read), ee (write), es (write)
+        #expect(bobCountAfterMsg2 >= 2, "Bob should clear DH secrets when processing/writing message 2")
+
+        // Alice reads message 2 (ee, es) and writes message 3 (se)
+        let msg3 = try alice.processHandshakeMessage(msg2)!
+        let aliceCountAfterMsg3 = aliceKeychain.secureClearDataCallCount
+        // Alice should have cleared: ee (read), es (read), se (write)
+        #expect(aliceCountAfterMsg3 >= 3, "Alice should clear DH secrets when processing/writing message 3")
+
+        // Bob reads message 3 (se)
+        _ = try bob.processHandshakeMessage(msg3)
+        let bobFinalCount = bobKeychain.secureClearDataCallCount
+        // Bob should have additionally cleared: se (read)
+        #expect(bobFinalCount > bobCountAfterMsg2, "Bob should clear DH secrets when processing message 3")
+    }
+}

localPackages/Noise/Tests/NoiseTests/NoiseRateLimiterTests.swift

@@ -0,0 +1,70 @@
+import XCTest
+import BitFoundation
+@testable import Noise
+
+final class NoiseRateLimiterTests: XCTestCase {
+    func test_allowHandshake_blocksAfterPerPeerLimit() {
+        let limiter = NoiseRateLimiter()
+        let peerID = makePeerID(1)
+
+        for _ in 0..<NoiseSecurityConstants.maxHandshakesPerMinute {
+            XCTAssertTrue(limiter.allowHandshake(from: peerID))
+        }
+
+        XCTAssertFalse(limiter.allowHandshake(from: peerID))
+    }
+
+    func test_allowHandshake_blocksAfterGlobalLimitAcrossPeers() {
+        let limiter = NoiseRateLimiter()
+
+        for index in 0..<NoiseSecurityConstants.maxGlobalHandshakesPerMinute {
+            XCTAssertTrue(limiter.allowHandshake(from: makePeerID(index)))
+        }
+
+        XCTAssertFalse(limiter.allowHandshake(from: makePeerID(10_000)))
+    }
+
+    func test_reset_clearsPerPeerHandshakeLimit() async {
+        let limiter = NoiseRateLimiter()
+        let peerID = makePeerID(7)
+
+        for _ in 0..<NoiseSecurityConstants.maxHandshakesPerMinute {
+            XCTAssertTrue(limiter.allowHandshake(from: peerID))
+        }
+        XCTAssertFalse(limiter.allowHandshake(from: peerID))
+
+        limiter.reset(for: peerID)
+        try? await Task.sleep(nanoseconds: 50_000_000)
+
+        XCTAssertTrue(limiter.allowHandshake(from: peerID))
+    }
+
+    func test_allowMessage_blocksAfterPerPeerLimit() {
+        let limiter = NoiseRateLimiter()
+        let peerID = makePeerID(9)
+
+        for _ in 0..<NoiseSecurityConstants.maxMessagesPerSecond {
+            XCTAssertTrue(limiter.allowMessage(from: peerID))
+        }
+
+        XCTAssertFalse(limiter.allowMessage(from: peerID))
+    }
+
+    func test_resetAll_clearsGlobalHandshakeLimit() async {
+        let limiter = NoiseRateLimiter()
+
+        for index in 0..<NoiseSecurityConstants.maxGlobalHandshakesPerMinute {
+            XCTAssertTrue(limiter.allowHandshake(from: makePeerID(index)))
+        }
+        XCTAssertFalse(limiter.allowHandshake(from: makePeerID(20_000)))
+
+        limiter.resetAll()
+        try? await Task.sleep(nanoseconds: 50_000_000)
+
+        XCTAssertTrue(limiter.allowHandshake(from: makePeerID(20_001)))
+    }
+
+    private func makePeerID(_ value: Int) -> PeerID {
+        PeerID(str: String(format: "%016x", value))
+    }
+}

localPackages/Noise/Tests/NoiseTests/NoiseTestVectors.json

@@ -0,0 +1,71 @@
+[
+    {
+        "protocol_name": "Noise_XX_25519_ChaChaPoly_SHA256",
+        "init_prologue": "4a6f686e2047616c74",
+        "init_static": "e61ef9919cde45dd5f82166404bd08e38bceb5dfdfded0a34c8df7ed542214d1",
+        "init_ephemeral": "893e28b9dc6ca8d611ab664754b8ceb7bac5117349a4439a6b0569da977c464a",
+        "resp_prologue": "4a6f686e2047616c74",
+        "resp_static": "4a3acbfdb163dec651dfa3194dece676d437029c62a408b4c5ea9114246e4893",
+        "resp_ephemeral": "bbdb4cdbd309f1a1f2e1456967fe288cadd6f712d65dc7b7793d5e63da6b375b",
+        "handshake_hash": "c8e5f64e846193be2a834104c2a009868d6c9f3bd3c186299888b488b2f1f58e",
+        "messages": [
+            {
+                "payload": "4c756477696720766f6e204d69736573",
+                "ciphertext": "ca35def5ae56cec33dc2036731ab14896bc4c75dbb07a61f879f8e3afa4c79444c756477696720766f6e204d69736573"
+            },
+            {
+                "payload": "4d757272617920526f746862617264",
+                "ciphertext": "95ebc60d2b1fa672c1f46a8aa265ef51bfe38e7ccb39ec5be34069f14480884381cbad1f276e038c48378ffce2b65285e08d6b68aaa3629a5a8639392490e5b9bd5269c2f1e4f488ed8831161f19b7815528f8982ffe09be9b5c412f8a0db50f8814c7194e83f23dbd8d162c9326ad"
+            },
+            {
+                "payload": "462e20412e20486179656b",
+                "ciphertext": "c7195ffacac1307ff99046f219750fc47693e23c3cb08b89c2af808b444850a80ae475b9df0f169ae80a89be0865b57f58c9fea0d4ec82a286427402f113e4b6ae769a1d95941d49b25030"
+            },
+            {
+                "payload": "4361726c204d656e676572",
+                "ciphertext": "96763ed773f8e47bb3712f0e29b3060ffc956ffc146cee53d5e1df"
+            },
+            {
+                "payload": "4a65616e2d426170746973746520536179",
+                "ciphertext": "3e40f15f6f3a46ae446b253bf8b1d9ffb6ed9b174d272328ff91a7e2e5c79c07f5"
+            },
+            {
+                "payload": "457567656e2042f6686d20766f6e2042617765726b",
+                "ciphertext": "eb3f3515110702e047a6c9da4478b6ead94873c11c0f2d710ddb3f09fce024b3a58502ae3f"
+            }
+        ]
+    },
+    {
+        "protocol_name": "Noise_XX_25519_ChaChaPoly_SHA256",
+        "init_prologue": "5468657265206973206e6f20726967687420616e642077726f6e672e2054686572652773206f6e6c792066756e20616e6420626f72696e672e",
+        "init_psks": [],
+        "init_static": "7dec208517a3b81a2861d7a71266d5d6dc944c5a8816634a86fe63198a0148ee",
+        "init_ephemeral": "a32daf21e93c0131495ce1d903181fde81cc46937daaeb990bae7c992709421e",
+        "resp_prologue": "5468657265206973206e6f20726967687420616e642077726f6e672e2054686572652773206f6e6c792066756e20616e6420626f72696e672e",
+        "resp_psks": [],
+        "resp_static": "4d0aed5098e3b4ef20357e9f686ce66204c792b358da2e475017d6c485304881",
+        "resp_ephemeral": "4eece0f195d026db035ff987597c429d3ad3bcc2944df37d649528951b2a27c5",
+        "messages": [
+            {
+                "payload": "d03c489139e645d0711a3c9e810d776b46a84912463fafa87b884eebf242dc34",
+                "ciphertext": "f9fa868ba97ab8a2686deccfaad5a484ee10a5bb85e3d1dce015a84797f92818d03c489139e645d0711a3c9e810d776b46a84912463fafa87b884eebf242dc34"
+            },
+            {
+                "payload": "d8190a92f7dc0c93dbea9118ba8055751fb7c6590c416ffbd419964132b99a85",
+                "ciphertext": "8c4e6fdb7d09d501a86f7eca5c234522751706ed409182c05cdf5f827d4dae47b81c6c5f43b025692c24391eefee725c17d8cb0fbe3e4abb8aedf42c4fd2592d4ea48ac08989d6ae8b4adae08b2c34087c808c7aa55a63c02b0fab9e930612336bd43eaea04d3c670a0a146691aa9cc9d357872320dc735dbc48580cffb553db"
+            },
+            {
+                "payload": "77891b19dcb92ef7c055b672c4a5aa7fdf1c84146b8b303459022729473ce254",
+                "ciphertext": "933ca6b5ed60df3df66121f0ab49a09e49efa45c613a86a3cecbf4c535cef2f83f72b42837b18e3572f2fdc2b74c331e2368a545cef54bdca081678ab0e9dd5348122459e0c034c851984d88ce610963d43cde6cfe73a67fbd5a63e8bfca96d0"
+            },
+            {
+                "payload": "d7efdf988072881941db045a42882433817555128fbf5663e56081712ec7d212",
+                "ciphertext": "54ef0ff0629e1aaa7685a2806ab111cba76b52331f2642276736f415868eacb69ab2577f3bda0cbf72f879685f6ed25f"
+            },
+            {
+                "payload": "dd7bf01a588bafb52c6cfba952e5d8fe35cc2b3f92b4730ae2474615157345ce",
+                "ciphertext": "356be70f110306d5c699bb834bb9d58d909e325924dfbec972e406e6f294dc63e1daebefe8a62a334facc8048ab4ad66"
+            }
+        ]
+    }
+]

localPackages/Noise/Tests/NoiseTests/TestHelpers.swift

@@ -0,0 +1,42 @@
+//
+// TestHelpers.swift
+// bitchatTests
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import Foundation
+import CryptoKit
+import BitFoundation
+
+// TODO: Combine with the one from the main target
+final class TestHelpers {
+    static func generateRandomData(length: Int) -> Data {
+        var data = Data(count: length)
+        _ = data.withUnsafeMutableBytes { bytes in
+            SecRandomCopyBytes(kSecRandomDefault, length, bytes.baseAddress!)
+        }
+        return data
+    }
+
+    @MainActor
+    static func waitUntil(
+        _ condition: @escaping () -> Bool,
+        timeout: TimeInterval = 5,
+        pollInterval: TimeInterval = 0.01
+    ) async -> Bool {
+        let start = Date()
+        while !condition() {
+            if Date().timeIntervalSince(start) > timeout {
+                return condition()
+            }
+            try? await sleep(pollInterval)
+        }
+        return true
+    }
+}
+
+func sleep(_ seconds: TimeInterval) async throws {
+    try await Task.sleep(nanoseconds: UInt64(seconds * 1_000_000_000))
+}