Extract Noise into a dedicated module

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
+}