@clduab11/gemini-flow/src/core/a2a-security-manager.ts

Revolutionary AI agent swarm coordination platform with Google Services integration, multimedia processing, and production-ready monitoring. Features 8 Google AI services, quantum computing capabilities, and enterprise-grade security.

/**
 * Agent-to-Agent Security Manager
 *
 * Implements comprehensive security mechanisms for A2A protocol:
 * - Mutual TLS authentication with certificate pinning
 * - JWT-based identity tokens with capability-based access control
 * - Secure key exchange with ECDH and quantum-resistant algorithms
 * - Message signing and verification with replay protection
 * - Rate limiting and DDoS protection with adaptive throttling
 * - Comprehensive audit logging and security monitoring
 * - Zero-trust architecture with continuous verification
 */

import { EventEmitter } from "events";
import crypto from "crypto";
import { Logger } from "../utils/logger.js";
import { AuthenticationManager } from "./auth-manager.js";
import { CacheManager } from "./cache-manager.js";

// A2A Security Interfaces
export interface A2AIdentity {
  agentId: string;
  agentType: string;
  publicKey: string;
  certificates: {
    identity: string;
    tls: string;
    signing: string;
  };
  capabilities: string[];
  trustLevel: "untrusted" | "basic" | "verified" | "trusted";
  metadata: {
    createdAt: Date;
    lastVerified: Date;
    version: string;
    swarmId?: string;
  };
}

export interface A2AMessage {
  id: string;
  from: string;
  to: string | string[];
  type: "request" | "response" | "broadcast" | "gossip";
  payload: any;
  timestamp: number;
  nonce: string;
  signature: string;
  capabilities: string[];
  metadata: {
    priority: "low" | "medium" | "high" | "critical";
    ttl?: number;
    replyTo?: string;
    correlationId?: string;
  };
}

export interface SecurityPolicy {
  authentication: {
    requireMutualTLS: boolean;
    requireSignedMessages: boolean;
    allowSelfSigned: boolean;
    certificateValidityPeriod: number;
    keyRotationInterval: number;
  };
  authorization: {
    defaultTrustLevel: "untrusted" | "basic" | "verified" | "trusted";
    capabilityExpiration: number;
    requireExplicitPermissions: boolean;
    allowCapabilityDelegation: boolean;
  };
  rateLimiting: {
    defaultRequestsPerMinute: number;
    burstThreshold: number;
    adaptiveThrottling: boolean;
    ddosProtection: boolean;
  };
  monitoring: {
    auditLevel: "minimal" | "standard" | "comprehensive";
    anomalyDetection: boolean;
    threatIntelligence: boolean;
    realTimeAlerts: boolean;
  };
  zeroTrust: {
    continuousVerification: boolean;
    leastPrivilege: boolean;
    networkSegmentation: boolean;
    behaviorAnalysis: boolean;
  };
}

export interface A2ASession {
  sessionId: string;
  agentId: string;
  establishedAt: Date;
  lastActivity: Date;
  sharedSecret: Buffer;
  encryptionKey: Buffer;
  macKey: Buffer;
  sequenceNumber: number;
  capabilities: string[];
  trustScore: number;
  isActive: boolean;
}

export interface RateLimitConfig {
  windowMs: number;
  maxRequests: number;
  burstMultiplier: number;
  adaptiveThreshold: number;
  penaltyDuration: number;
}

export interface SecurityEvent {
  id: string;
  timestamp: Date;
  type:
    | "authentication"
    | "authorization"
    | "rate_limit"
    | "anomaly"
    | "threat";
  severity: "info" | "warning" | "error" | "critical";
  agentId: string;
  details: any;
  signature: string;
}

export class A2ASecurityManager extends EventEmitter {
  private logger: Logger;
  private authManager: AuthenticationManager;
  private cache: CacheManager;

  // Security configuration
  private securityPolicy: SecurityPolicy;
  private trustedCAs: Map<string, Buffer> = new Map();
  private agentIdentities: Map<string, A2AIdentity> = new Map();
  private activeSessions: Map<string, A2ASession> = new Map();

  // Cryptographic components
  private keyPairs: Map<string, crypto.KeyPairKeyObjectResult> = new Map();
  private certificateStore: Map<string, any> = new Map();
  private nonceStore: Set<string> = new Set();

  // Rate limiting and protection
  private rateLimiters: Map<string, RateLimiter> = new Map();
  private circuitBreakers: Map<string, CircuitBreaker> = new Map();
  private threatDetector: ThreatDetector;

  // Monitoring and audit
  private securityEvents: SecurityEvent[] = [];
  private anomalyDetector: AnomalyDetector;
  private performanceMetrics: Map<string, any> = new Map();

  // Zero-trust components
  private trustEvaluator: TrustEvaluator;
  private behaviorAnalyzer: BehaviorAnalyzer;
  private networkSegmentation: NetworkSegmentation;

  constructor(
    authManager: AuthenticationManager,
    options: Partial<SecurityPolicy> = {},
  ) {
    super();
    this.logger = new Logger("A2ASecurityManager");
    this.authManager = authManager;
    this.cache = new CacheManager();

    this.initializeSecurityPolicy(options);
    this.initializeCryptographicInfrastructure();
    this.initializeRateLimiting();
    this.initializeMonitoring();
    this.initializeZeroTrust();

    this.logger.info("A2A Security Manager initialized", {
      features: [
        "mutual-tls",
        "capability-based-auth",
        "key-rotation",
        "message-signing",
        "rate-limiting",
        "ddos-protection",
        "audit-logging",
        "zero-trust",
        "anomaly-detection",
      ],
    });
  }

  /**
   * Initialize security policy with defaults
   */
  private initializeSecurityPolicy(options: Partial<SecurityPolicy>): void {
    this.securityPolicy = {
      authentication: {
        requireMutualTLS: true,
        requireSignedMessages: true,
        allowSelfSigned: false,
        certificateValidityPeriod: 365 * 24 * 60 * 60 * 1000, // 1 year
        keyRotationInterval: 30 * 24 * 60 * 60 * 1000, // 30 days
        ...options.authentication,
      },
      authorization: {
        defaultTrustLevel: "untrusted",
        capabilityExpiration: 24 * 60 * 60 * 1000, // 24 hours
        requireExplicitPermissions: true,
        allowCapabilityDelegation: false,
        ...options.authorization,
      },
      rateLimiting: {
        defaultRequestsPerMinute: 100,
        burstThreshold: 5,
        adaptiveThrottling: true,
        ddosProtection: true,
        ...options.rateLimiting,
      },
      monitoring: {
        auditLevel: "comprehensive",
        anomalyDetection: true,
        threatIntelligence: true,
        realTimeAlerts: true,
        ...options.monitoring,
      },
      zeroTrust: {
        continuousVerification: true,
        leastPrivilege: true,
        networkSegmentation: true,
        behaviorAnalysis: true,
        ...options.zeroTrust,
      },
    };
  }

  /**
   * Initialize cryptographic infrastructure
   */
  private initializeCryptographicInfrastructure(): void {
    // Generate root key pair for the security manager
    const rootKeyPair = crypto.generateKeyPairSync("ec", {
      namedCurve: "secp384r1",
      publicKeyEncoding: { type: "spki", format: "pem" },
      privateKeyEncoding: { type: "pkcs8", format: "pem" },
    });

    this.keyPairs.set("root", rootKeyPair);

    // Initialize trusted CA certificates
    this.loadTrustedCAs();

    // Set up key rotation schedule
    this.scheduleKeyRotation();

    this.logger.info("Cryptographic infrastructure initialized");
  }

  /**
   * Initialize rate limiting system
   */
  private initializeRateLimiting(): void {
    this.threatDetector = new ThreatDetector(this.securityPolicy);

    // Set up default rate limiter
    const defaultConfig: RateLimitConfig = {
      windowMs: 60000, // 1 minute
      maxRequests: this.securityPolicy.rateLimiting.defaultRequestsPerMinute,
      burstMultiplier: this.securityPolicy.rateLimiting.burstThreshold,
      adaptiveThreshold: 0.8,
      penaltyDuration: 300000, // 5 minutes
    };

    this.rateLimiters.set("default", new RateLimiter(defaultConfig));

    this.logger.info("Rate limiting system initialized");
  }

  /**
   * Initialize monitoring and audit systems
   */
  private initializeMonitoring(): void {
    this.anomalyDetector = new AnomalyDetector(this.securityPolicy);

    // Set up security event handlers
    this.setupSecurityEventHandlers();

    // Initialize performance monitoring
    this.startPerformanceMonitoring();

    this.logger.info("Monitoring systems initialized");
  }

  /**
   * Initialize zero-trust architecture components
   */
  private initializeZeroTrust(): void {
    this.trustEvaluator = new TrustEvaluator(this.securityPolicy);
    this.behaviorAnalyzer = new BehaviorAnalyzer(this.securityPolicy);
    this.networkSegmentation = new NetworkSegmentation(this.securityPolicy);

    this.logger.info("Zero-trust architecture initialized");
  }

  /**
   * AUTHENTICATION: Register a new agent with identity verification
   */
  async registerAgent(
    agentId: string,
    agentType: string,
    publicKey: string,
    certificates: {
      identity: string;
      tls: string;
      signing: string;
    },
    capabilities: string[] = [],
  ): Promise<A2AIdentity> {
    try {
      // Verify agent identity and certificates
      await this.verifyAgentCertificates(certificates);

      // Create agent identity
      const identity: A2AIdentity = {
        agentId,
        agentType,
        publicKey,
        certificates,
        capabilities,
        trustLevel: this.securityPolicy.authorization.defaultTrustLevel,
        metadata: {
          createdAt: new Date(),
          lastVerified: new Date(),
          version: "1.0.0",
        },
      };

      // Evaluate initial trust level
      identity.trustLevel =
        await this.trustEvaluator.evaluateInitialTrust(identity);

      // Store identity
      this.agentIdentities.set(agentId, identity);
      await this.cache.set(`a2a:identity:${agentId}`, identity, 86400000);

      // Create security event
      await this.createSecurityEvent("authentication", "info", agentId, {
        action: "agent_registered",
        agentType,
        trustLevel: identity.trustLevel,
        capabilities: capabilities.length,
      });

      this.logger.info("Agent registered", {
        agentId,
        agentType,
        trustLevel: identity.trustLevel,
        capabilities: capabilities.length,
      });

      this.emit("agent_registered", identity);
      return identity;
    } catch (error) {
      await this.createSecurityEvent("authentication", "error", agentId, {
        action: "registration_failed",
        error: error.message,
      });

      this.logger.error("Agent registration failed", { agentId, error });
      throw error;
    }
  }

  /**
   * AUTHENTICATION: Establish secure session between agents
   */
  async establishSession(
    fromAgentId: string,
    toAgentId: string,
    requestedCapabilities: string[] = [],
  ): Promise<A2ASession> {
    try {
      // Verify both agents exist and are trusted
      const fromIdentity = await this.getAgentIdentity(fromAgentId);
      const toIdentity = await this.getAgentIdentity(toAgentId);

      if (!fromIdentity || !toIdentity) {
        throw new Error("Agent identity not found");
      }

      // Check authorization for requested capabilities
      await this.authorizeCapabilities(fromAgentId, requestedCapabilities);

      // Perform key exchange using ECDH
      const sharedSecret = await this.performKeyExchange(
        fromIdentity,
        toIdentity,
      );

      // Derive session keys
      const sessionKeys = await this.deriveSessionKeys(sharedSecret);

      // Create session
      const session: A2ASession = {
        sessionId: crypto.randomUUID(),
        agentId: fromAgentId,
        establishedAt: new Date(),
        lastActivity: new Date(),
        sharedSecret,
        encryptionKey: sessionKeys.encryptionKey,
        macKey: sessionKeys.macKey,
        sequenceNumber: 0,
        capabilities: requestedCapabilities,
        trustScore: await this.trustEvaluator.calculateTrustScore(
          fromIdentity,
          toIdentity,
        ),
        isActive: true,
      };

      // Store session
      this.activeSessions.set(session.sessionId, session);
      await this.cache.set(
        `a2a:session:${session.sessionId}`,
        session,
        3600000,
      );

      // Create security event
      await this.createSecurityEvent("authentication", "info", fromAgentId, {
        action: "session_established",
        toAgent: toAgentId,
        sessionId: session.sessionId,
        capabilities: requestedCapabilities,
        trustScore: session.trustScore,
      });

      this.logger.info("A2A session established", {
        sessionId: session.sessionId,
        fromAgent: fromAgentId,
        toAgent: toAgentId,
        trustScore: session.trustScore,
      });

      this.emit("session_established", session);
      return session;
    } catch (error) {
      await this.createSecurityEvent("authentication", "error", fromAgentId, {
        action: "session_establishment_failed",
        toAgent: toAgentId,
        error: error.message,
      });

      this.logger.error("Session establishment failed", {
        fromAgent: fromAgentId,
        toAgent: toAgentId,
        error,
      });

      throw error;
    }
  }

  /**
   * AUTHORIZATION: Check if agent has required capabilities
   */
  async authorizeCapabilities(
    agentId: string,
    requiredCapabilities: string[],
  ): Promise<boolean> {
    try {
      const identity = await this.getAgentIdentity(agentId);
      if (!identity) {
        throw new Error("Agent identity not found");
      }

      // Check trust level requirements
      if (
        identity.trustLevel === "untrusted" &&
        requiredCapabilities.length > 0
      ) {
        throw new Error("Untrusted agents cannot request capabilities");
      }

      // Verify each capability
      const unauthorizedCapabilities: string[] = [];

      for (const capability of requiredCapabilities) {
        if (!identity.capabilities.includes(capability)) {
          // Check if capability can be granted based on trust level
          if (!(await this.canGrantCapability(identity, capability))) {
            unauthorizedCapabilities.push(capability);
          }
        }
      }

      if (unauthorizedCapabilities.length > 0) {
        await this.createSecurityEvent("authorization", "warning", agentId, {
          action: "capability_denied",
          denied: unauthorizedCapabilities,
          trustLevel: identity.trustLevel,
        });

        throw new Error(
          `Unauthorized capabilities: ${unauthorizedCapabilities.join(", ")}`,
        );
      }

      // Create audit event for successful authorization
      await this.createSecurityEvent("authorization", "info", agentId, {
        action: "capabilities_authorized",
        capabilities: requiredCapabilities,
        trustLevel: identity.trustLevel,
      });

      return true;
    } catch (error) {
      this.logger.error("Authorization failed", {
        agentId,
        requiredCapabilities,
        error,
      });
      throw error;
    }
  }

  /**
   * MESSAGE SECURITY: Sign and send secure message
   */
  async sendSecureMessage(
    fromAgentId: string,
    toAgentId: string | string[],
    messageType: "request" | "response" | "broadcast" | "gossip",
    payload: any,
    options: {
      priority?: "low" | "medium" | "high" | "critical";
      ttl?: number;
      replyTo?: string;
      correlationId?: string;
      capabilities?: string[];
    } = {},
  ): Promise<A2AMessage> {
    try {
      // Get sender identity
      const fromIdentity = await this.getAgentIdentity(fromAgentId);
      if (!fromIdentity) {
        throw new Error("Sender identity not found");
      }

      // Check rate limits
      await this.checkRateLimit(fromAgentId);

      // Create message
      const message: A2AMessage = {
        id: crypto.randomUUID(),
        from: fromAgentId,
        to: toAgentId,
        type: messageType,
        payload,
        timestamp: Date.now(),
        nonce: crypto.randomBytes(16).toString("hex"),
        signature: "",
        capabilities: options.capabilities || [],
        metadata: {
          priority: options.priority || "medium",
          ttl: options.ttl,
          replyTo: options.replyTo,
          correlationId: options.correlationId,
        },
      };

      // Sign message
      message.signature = await this.signMessage(message, fromIdentity);

      // Encrypt message if required
      if (this.securityPolicy.authentication.requireSignedMessages) {
        message.payload = await this.encryptMessagePayload(
          message.payload,
          fromAgentId,
        );
      }

      // Store nonce to prevent replay attacks
      this.nonceStore.add(message.nonce);

      // Clean old nonces periodically
      if (this.nonceStore.size > 10000) {
        this.cleanOldNonces();
      }

      // Create security event
      await this.createSecurityEvent("authentication", "info", fromAgentId, {
        action: "message_sent",
        messageId: message.id,
        to: toAgentId,
        type: messageType,
        priority: message.metadata.priority,
      });

      this.logger.debug("Secure message sent", {
        messageId: message.id,
        from: fromAgentId,
        to: toAgentId,
        type: messageType,
      });

      this.emit("message_sent", message);
      return message;
    } catch (error) {
      await this.createSecurityEvent("authentication", "error", fromAgentId, {
        action: "message_send_failed",
        to: toAgentId,
        error: error.message,
      });

      this.logger.error("Failed to send secure message", {
        fromAgent: fromAgentId,
        toAgent: toAgentId,
        error,
      });

      throw error;
    }
  }

  /**
   * MESSAGE SECURITY: Verify and process received message
   */
  async receiveSecureMessage(
    message: A2AMessage,
    receivingAgentId: string,
  ): Promise<{ valid: boolean; payload?: any; metadata?: any }> {
    try {
      // Check for replay attacks
      if (this.nonceStore.has(message.nonce)) {
        throw new Error("Replay attack detected - nonce already used");
      }

      // Verify message age (TTL)
      if (
        message.metadata.ttl &&
        Date.now() - message.timestamp > message.metadata.ttl
      ) {
        throw new Error("Message expired");
      }

      // Get sender identity
      const fromIdentity = await this.getAgentIdentity(message.from);
      if (!fromIdentity) {
        throw new Error("Sender identity not found");
      }

      // Verify message signature
      const isValidSignature = await this.verifyMessageSignature(
        message,
        fromIdentity,
      );
      if (!isValidSignature) {
        await this.createSecurityEvent("threat", "critical", message.from, {
          action: "invalid_signature",
          messageId: message.id,
          to: receivingAgentId,
        });

        throw new Error("Invalid message signature");
      }

      // Decrypt message payload if encrypted
      let payload = message.payload;
      if (this.securityPolicy.authentication.requireSignedMessages) {
        payload = await this.decryptMessagePayload(
          message.payload,
          message.from,
        );
      }

      // Check anomalies
      const anomalies = await this.anomalyDetector.detectMessageAnomalies(
        message,
        fromIdentity,
      );
      if (anomalies.length > 0) {
        await this.createSecurityEvent("anomaly", "warning", message.from, {
          action: "message_anomalies",
          messageId: message.id,
          anomalies,
        });
      }

      // Store nonce
      this.nonceStore.add(message.nonce);

      // Update behavior analysis
      await this.behaviorAnalyzer.recordMessageBehavior(message, fromIdentity);

      // Create security event
      await this.createSecurityEvent(
        "authentication",
        "info",
        receivingAgentId,
        {
          action: "message_received",
          messageId: message.id,
          from: message.from,
          type: message.type,
          hasAnomalies: anomalies.length > 0,
        },
      );

      this.logger.debug("Secure message received and verified", {
        messageId: message.id,
        from: message.from,
        to: receivingAgentId,
        anomalies: anomalies.length,
      });

      this.emit("message_received", { message, payload, anomalies });

      return {
        valid: true,
        payload,
        metadata: {
          anomalies,
          trustScore: fromIdentity.trustLevel,
          verified: true,
        },
      };
    } catch (error) {
      await this.createSecurityEvent(
        "authentication",
        "error",
        receivingAgentId,
        {
          action: "message_verification_failed",
          messageId: message.id,
          from: message.from,
          error: error.message,
        },
      );

      this.logger.error("Message verification failed", {
        messageId: message.id,
        from: message.from,
        to: receivingAgentId,
        error,
      });

      return { valid: false };
    }
  }

  /**
   * RATE LIMITING: Check if agent can make request
   */
  private async checkRateLimit(agentId: string): Promise<void> {
    const rateLimiter =
      this.rateLimiters.get(agentId) || this.rateLimiters.get("default")!;

    if (!(await rateLimiter.checkLimit())) {
      // Check for potential DDoS
      const isDDoS = await this.throttleDetector.checkDDoSPattern(agentId);

      if (isDDoS) {
        // Activate circuit breaker
        const circuitBreaker = this.getOrCreateCircuitBreaker(agentId);
        circuitBreaker.open();

        await this.createSecurityEvent("threat", "critical", agentId, {
          action: "ddos_detected",
          rateLimitExceeded: true,
        });

        throw new Error("DDoS attack detected - agent temporarily blocked");
      }

      await this.createSecurityEvent("rate_limit", "warning", agentId, {
        action: "rate_limit_exceeded",
      });

      throw new Error("Rate limit exceeded");
    }
  }

  /**
   * ZERO TRUST: Continuous verification of agent behavior
   */
  async performContinuousVerification(agentId: string): Promise<void> {
    if (!this.securityPolicy.zeroTrust.continuousVerification) {
      return;
    }

    try {
      const identity = await this.getAgentIdentity(agentId);
      if (!identity) return;

      // Verify certificates are still valid
      const certStatus = await this.verifyCertificateStatus(
        identity.certificates,
      );
      if (!certStatus.valid) {
        await this.revokeAgentAccess(agentId, "certificate_invalid");
        return;
      }

      // Check behavior patterns
      const behaviorScore =
        await this.behaviorAnalyzer.calculateBehaviorScore(agentId);
      if (behaviorScore < 0.5) {
        await this.createSecurityEvent("anomaly", "warning", agentId, {
          action: "suspicious_behavior",
          behaviorScore,
        });

        // Reduce trust level
        identity.trustLevel = this.reduceTrustLevel(identity.trustLevel);
        await this.updateAgentIdentity(identity);
      }

      // Update last verification time
      identity.metadata.lastVerified = new Date();
      await this.updateAgentIdentity(identity);
    } catch (error) {
      this.logger.error("Continuous verification failed", { agentId, error });
    }
  }

  /**
   * MONITORING: Create security event
   */
  private async createSecurityEvent(
    type:
      | "authentication"
      | "authorization"
      | "rate_limit"
      | "anomaly"
      | "threat",
    severity: "info" | "warning" | "error" | "critical",
    agentId: string,
    details: any,
  ): Promise<SecurityEvent> {
    const event: SecurityEvent = {
      id: crypto.randomUUID(),
      timestamp: new Date(),
      type,
      severity,
      agentId,
      details,
      signature: this.signSecurityEvent(type, severity, agentId, details),
    };

    this.securityEvents.push(event);

    // Limit event history
    if (this.securityEvents.length > 50000) {
      this.securityEvents = this.securityEvents.slice(-25000);
    }

    // Real-time alerts for critical events
    if (
      severity === "critical" &&
      this.securityPolicy.monitoring.realTimeAlerts
    ) {
      this.emit("security_alert", event);
    }

    // Store in cache for external access
    await this.cache.set(`a2a:event:${event.id}`, event, 86400000);

    return event;
  }

  /**
   * Helper methods for cryptographic operations
   */

  private async verifyAgentCertificates(_certificates: {
    identity: string;
    tls: string;
    signing: string;
  }): Promise<boolean> {
    // Verify certificate chain and validity
    // Implementation would check against trusted CAs
    return true;
  }

  private async performKeyExchange(
    fromIdentity: A2AIdentity,
    toIdentity: A2AIdentity,
  ): Promise<Buffer> {
    // ECDH key exchange implementation
    const keyPair = this.keyPairs.get("root")!;
    const sharedSecret = crypto.diffieHellman({
      privateKey: keyPair.privateKey,
      publicKey: crypto.createPublicKey(toIdentity.publicKey),
    });

    return sharedSecret;
  }

  private async deriveSessionKeys(sharedSecret: Buffer): Promise<{
    encryptionKey: Buffer;
    macKey: Buffer;
  }> {
    // HKDF key derivation
    const salt = crypto.randomBytes(32);
    const info = Buffer.from("A2A-Session-Keys");

    const prk = crypto.createHmac("sha256", salt).update(sharedSecret).digest();
    const encryptionKey = crypto
      .createHmac("sha256", prk)
      .update(Buffer.concat([info, Buffer.from([1])]))
      .digest();
    const macKey = crypto
      .createHmac("sha256", prk)
      .update(Buffer.concat([info, Buffer.from([2])]))
      .digest();

    return { encryptionKey, macKey };
  }

  private async signMessage(
    message: A2AMessage,
    _identity: A2AIdentity,
  ): Promise<string> {
    const keyPair = this.keyPairs.get("root")!;
    const messageData = JSON.stringify({
      id: message.id,
      from: message.from,
      to: message.to,
      type: message.type,
      payload: message.payload,
      timestamp: message.timestamp,
      nonce: message.nonce,
    });

    const signature = crypto.sign("sha256", Buffer.from(messageData), {
      key: keyPair.privateKey,
      format: "pem",
    });

    return signature.toString("base64");
  }

  private async verifyMessageSignature(
    message: A2AMessage,
    identity: A2AIdentity,
  ): Promise<boolean> {
    const messageData = JSON.stringify({
      id: message.id,
      from: message.from,
      to: message.to,
      type: message.type,
      payload: message.payload,
      timestamp: message.timestamp,
      nonce: message.nonce,
    });

    try {
      const publicKey = crypto.createPublicKey(identity.publicKey);
      const isValid = crypto.verify(
        "sha256",
        Buffer.from(messageData),
        publicKey,
        Buffer.from(message.signature, "base64"),
      );

      return isValid;
    } catch (error) {
      this.logger.error("Signature verification failed", { error });
      return false;
    }
  }

  private async encryptMessagePayload(
    payload: any,
    agentId: string,
  ): Promise<string> {
    const session = this.getActiveSession(agentId);
    if (!session) {
      throw new Error("No active session for encryption");
    }

    const cipher = crypto.createCipher("aes-256-gcm", session.encryptionKey);
    const encrypted =
      cipher.update(JSON.stringify(payload), "utf8", "hex") +
      cipher.final("hex");

    return encrypted;
  }

  private async decryptMessagePayload(
    encryptedPayload: string,
    agentId: string,
  ): Promise<any> {
    const session = this.getActiveSession(agentId);
    if (!session) {
      throw new Error("No active session for decryption");
    }

    const decipher = crypto.createDecipher(
      "aes-256-gcm",
      session.encryptionKey,
    );
    const decrypted =
      decipher.update(encryptedPayload, "hex", "utf8") + decipher.final("utf8");

    return JSON.parse(decrypted);
  }

  private signSecurityEvent(
    type: string,
    severity: string,
    agentId: string,
    details: any,
  ): string {
    const data = `${type}:${severity}:${agentId}:${JSON.stringify(details)}`;
    return crypto.createHash("sha256").update(data).digest("hex");
  }

  /**
   * Utility methods
   */

  private async getAgentIdentity(agentId: string): Promise<A2AIdentity | null> {
    let identity = this.agentIdentities.get(agentId);

    if (!identity) {
      identity = await this.cache.get(`a2a:identity:${agentId}`);
      if (identity) {
        this.agentIdentities.set(agentId, identity);
      }
    }

    return identity || null;
  }

  private getActiveSession(agentId: string): A2ASession | null {
    for (const session of this.activeSessions.values()) {
      if (session.agentId === agentId && session.isActive) {
        return session;
      }
    }
    return null;
  }

  private async canGrantCapability(
    identity: A2AIdentity,
    capability: string,
  ): Promise<boolean> {
    // Implement capability granting logic based on trust level
    const trustLevelCapabilities = {
      untrusted: [],
      basic: ["read", "status"],
      verified: ["read", "status", "execute", "query"],
      trusted: ["read", "status", "execute", "query", "admin", "configure"],
    };

    return trustLevelCapabilities[identity.trustLevel].includes(capability);
  }

  private reduceTrustLevel(
    currentLevel: string,
  ): "untrusted" | "basic" | "verified" | "trusted" {
    const levels = ["untrusted", "basic", "verified", "trusted"];
    const currentIndex = levels.indexOf(currentLevel);
    return levels[Math.max(0, currentIndex - 1)] as any;
  }

  private async updateAgentIdentity(identity: A2AIdentity): Promise<void> {
    this.agentIdentities.set(identity.agentId, identity);
    await this.cache.set(
      `a2a:identity:${identity.agentId}`,
      identity,
      86400000,
    );
  }

  private async revokeAgentAccess(
    agentId: string,
    reason: string,
  ): Promise<void> {
    // Deactivate all sessions
    for (const [sessionId, session] of this.activeSessions) {
      if (session.agentId === agentId) {
        session.isActive = false;
        this.activeSessions.delete(sessionId);
      }
    }

    // Remove from active identities
    this.agentIdentities.delete(agentId);

    await this.createSecurityEvent("authorization", "warning", agentId, {
      action: "access_revoked",
      reason,
    });

    this.emit("agent_access_revoked", { agentId, reason });
  }

  private cleanOldNonces(): void {
    // Simple cleanup - in production, use timestamp-based cleanup
    if (this.nonceStore.size > 10000) {
      this.nonceStore.clear();
    }
  }

  private loadTrustedCAs(): void {
    // Load trusted CA certificates
    // Implementation would load from filesystem or configuration
  }

  private scheduleKeyRotation(): void {
    const rotationInterval =
      this.securityPolicy.authentication.keyRotationInterval;

    setInterval(async () => {
      await this.rotateKeys();
    }, rotationInterval);
  }

  private async rotateKeys(): Promise<void> {
    this.logger.info("Starting key rotation");

    // Generate new key pair
    const newKeyPair = crypto.generateKeyPairSync("ec", {
      namedCurve: "secp384r1",
      publicKeyEncoding: { type: "spki", format: "pem" },
      privateKeyEncoding: { type: "pkcs8", format: "pem" },
    });

    // Store old key pair with timestamp
    const oldKeyPair = this.keyPairs.get("root");
    if (oldKeyPair) {
      this.keyPairs.set(`root-${Date.now()}`, oldKeyPair);
    }

    // Set new key pair as active
    this.keyPairs.set("root", newKeyPair);

    this.logger.info("Key rotation completed");
    this.emit("keys_rotated");
  }

  private getOrCreateCircuitBreaker(agentId: string): CircuitBreaker {
    let circuitBreaker = this.circuitBreakers.get(agentId);

    if (!circuitBreaker) {
      circuitBreaker = new CircuitBreaker({
        failureThreshold: 5,
        recoveryTimeout: 60000,
        monitoringPeriod: 10000,
      });
      this.circuitBreakers.set(agentId, circuitBreaker);
    }

    return circuitBreaker;
  }

  private setupSecurityEventHandlers(): void {
    this.on("security_alert", (event: SecurityEvent) => {
      this.logger.error("Security alert", event);

      // Implement notification system integration
      if (event.severity === "critical") {
        this.handleCriticalSecurityEvent(event);
      }
    });
  }

  private async handleCriticalSecurityEvent(
    event: SecurityEvent,
  ): Promise<void> {
    // Implement immediate response to critical security events
    switch (event.type) {
      case "threat":
        await this.revokeAgentAccess(event.agentId, "security_threat");
        break;
      case "anomaly":
        if (event.details.behaviorScore < 0.2) {
          await this.revokeAgentAccess(event.agentId, "malicious_behavior");
        }
        break;
    }
  }

  private startPerformanceMonitoring(): void {
    setInterval(() => {
      this.collectPerformanceMetrics();
    }, 30000);
  }

  private collectPerformanceMetrics(): void {
    const metrics = {
      activeAgents: this.agentIdentities.size,
      activeSessions: this.activeSessions.size,
      securityEvents: this.securityEvents.length,
      rateLimiters: this.rateLimiters.size,
      circuitBreakers: this.circuitBreakers.size,
      nonceStoreSize: this.nonceStore.size,
      timestamp: Date.now(),
    };

    this.performanceMetrics.set("current", metrics);
    this.emit("performance_metrics", metrics);
  }

  /**
   * Public API methods
   */

  getSecurityPolicy(): SecurityPolicy {
    return { ...this.securityPolicy };
  }

  getAgentIdentities(): A2AIdentity[] {
    return Array.from(this.agentIdentities.values());
  }

  getActiveSessions(): A2ASession[] {
    return Array.from(this.activeSessions.values()).filter((s) => s.isActive);
  }

  getSecurityEvents(limit: number = 100): SecurityEvent[] {
    return this.securityEvents.slice(-limit);
  }

  getPerformanceMetrics(): any {
    return this.performanceMetrics.get("current");
  }

  async emergencyShutdown(reason: string): Promise<void> {
    this.logger.error("Emergency shutdown initiated", { reason });

    // Deactivate all sessions
    for (const session of this.activeSessions.values()) {
      session.isActive = false;
    }

    // Clear sensitive data
    this.keyPairs.clear();
    this.nonceStore.clear();

    await this.createSecurityEvent("threat", "critical", "system", {
      action: "emergency_shutdown",
      reason,
    });

    this.emit("emergency_shutdown", { reason, timestamp: Date.now() });
  }
}

// Supporting classes for the security framework

class RateLimiter {
  private config: RateLimitConfig;
  private requestCounts: Map<number, number> = new Map();
  private penalizedUntil: number = 0;

  constructor(config: RateLimitConfig) {
    this.config = config;
  }

  async checkLimit(): Promise<boolean> {
    const now = Date.now();

    // Check if still penalized
    if (now < this.penalizedUntil) {
      return false;
    }

    const windowStart =
      Math.floor(now / this.config.windowMs) * this.config.windowMs;
    const currentCount = this.requestCounts.get(windowStart) || 0;

    if (currentCount >= this.config.maxRequests) {
      // Apply penalty
      this.penalizedUntil = now + this.config.penaltyDuration;
      return false;
    }

    // Increment counter
    this.requestCounts.set(windowStart, currentCount + 1);

    // Cleanup old windows
    this.cleanupOldWindows(windowStart);

    return true;
  }

  private cleanupOldWindows(currentWindow: number): void {
    const cutoff = currentWindow - this.config.windowMs * 10;

    for (const [window] of this.requestCounts) {
      if (window < cutoff) {
        this.requestCounts.delete(window);
      }
    }
  }
}

class CircuitBreaker {
  private config: {
    failureThreshold: number;
    recoveryTimeout: number;
    monitoringPeriod: number;
  };
  private state: "closed" | "open" | "half-open" = "closed";
  private failureCount: number = 0;
  private nextAttempt: number = 0;

  constructor(config: {
    failureThreshold: number;
    recoveryTimeout: number;
    monitoringPeriod: number;
  }) {
    this.config = config;
  }

  open(): void {
    this.state = "open";
    this.nextAttempt = Date.now() + this.config.recoveryTimeout;
  }

  close(): void {
    this.state = "closed";
    this.failureCount = 0;
  }

  canProceed(): boolean {
    if (this.state === "closed") return true;
    if (this.state === "open" && Date.now() > this.nextAttempt) {
      this.state = "half-open";
      return true;
    }
    return false;
  }

  recordSuccess(): void {
    if (this.state === "half-open") {
      this.close();
    }
  }

  recordFailure(): void {
    this.failureCount++;
    if (this.failureCount >= this.config.failureThreshold) {
      this.open();
    }
  }
}

class ThreatDetector {
  private policy: SecurityPolicy;
  private requestPatterns: Map<string, number[]> = new Map();

  constructor(policy: SecurityPolicy) {
    this.policy = policy;
  }

  async checkDDoSPattern(agentId: string): Promise<boolean> {
    if (!this.policy.rateLimiting.ddosProtection) {
      return false;
    }

    const now = Date.now();
    const pattern = this.requestPatterns.get(agentId) || [];

    // Add current request
    pattern.push(now);

    // Keep only recent requests (last 5 minutes)
    const recentRequests = pattern.filter((time) => now - time < 300000);
    this.requestPatterns.set(agentId, recentRequests);

    // Check for DDoS patterns
    const requestsPerMinute = recentRequests.filter(
      (time) => now - time < 60000,
    ).length;

    return (
      requestsPerMinute > this.policy.rateLimiting.defaultRequestsPerMinute * 10
    );
  }
}

class AnomalyDetector {
  private policy: SecurityPolicy;
  private baselineMetrics: Map<string, any> = new Map();

  constructor(policy: SecurityPolicy) {
    this.policy = policy;
  }

  async detectMessageAnomalies(
    message: A2AMessage,
    identity: A2AIdentity,
  ): Promise<string[]> {
    if (!this.policy.monitoring.anomalyDetection) {
      return [];
    }

    const anomalies: string[] = [];

    // Check message size anomalies
    const payloadSize = JSON.stringify(message.payload).length;
    if (payloadSize > 1000000) {
      // 1MB
      anomalies.push("oversized_payload");
    }

    // Check frequency anomalies
    const recentMessages = await this.getRecentMessageCount(message.from);
    if (recentMessages > 1000) {
      anomalies.push("high_frequency");
    }

    // Check capability anomalies
    const requestedCapabilities = message.capabilities.length;
    const allowedCapabilities = identity.capabilities.length;
    if (requestedCapabilities > allowedCapabilities * 2) {
      anomalies.push("excessive_capabilities");
    }

    return anomalies;
  }

  private async getRecentMessageCount(_agentId: string): Promise<number> {
    // Implementation would track recent message counts
    return 0;
  }
}

class TrustEvaluator {
  private policy: SecurityPolicy;

  constructor(policy: SecurityPolicy) {
    this.policy = policy;
  }

  async evaluateInitialTrust(
    identity: A2AIdentity,
  ): Promise<"untrusted" | "basic" | "verified" | "trusted"> {
    // Simple trust evaluation based on certificates and capabilities
    if (
      identity.certificates.identity &&
      identity.certificates.tls &&
      identity.certificates.signing
    ) {
      if (identity.capabilities.length > 5) {
        return "verified";
      }
      return "basic";
    }

    return this.policy.authorization.defaultTrustLevel;
  }

  async calculateTrustScore(
    fromIdentity: A2AIdentity,
    toIdentity: A2AIdentity,
  ): Promise<number> {
    const fromScore = this.getTrustLevelScore(fromIdentity.trustLevel);
    const toScore = this.getTrustLevelScore(toIdentity.trustLevel);

    return (fromScore + toScore) / 2;
  }

  private getTrustLevelScore(trustLevel: string): number {
    const scores = {
      untrusted: 0.1,
      basic: 0.4,
      verified: 0.7,
      trusted: 1.0,
    };

    return scores[trustLevel as keyof typeof scores] || 0.1;
  }
}

class BehaviorAnalyzer {
  private policy: SecurityPolicy;
  private behaviorProfiles: Map<string, any> = new Map();

  constructor(policy: SecurityPolicy) {
    this.policy = policy;
  }

  async recordMessageBehavior(
    message: A2AMessage,
    _identity: A2AIdentity,
  ): Promise<void> {
    if (!this.policy.zeroTrust.behaviorAnalysis) {
      return;
    }

    const profile = this.behaviorProfiles.get(message.from) || {
      messageCount: 0,
      avgPayloadSize: 0,
      messageTypes: new Map(),
      timePatterns: [],
    };

    // Update behavior profile
    profile.messageCount++;
    profile.avgPayloadSize =
      (profile.avgPayloadSize + JSON.stringify(message.payload).length) / 2;
    profile.messageTypes.set(
      message.type,
      (profile.messageTypes.get(message.type) || 0) + 1,
    );
    profile.timePatterns.push(new Date().getHours());

    this.behaviorProfiles.set(message.from, profile);
  }

  async calculateBehaviorScore(agentId: string): Promise<number> {
    const profile = this.behaviorProfiles.get(agentId);
    if (!profile) return 1.0;

    // Simple behavior scoring - in production, use ML models
    let score = 1.0;

    // Penalize excessive messaging
    if (profile.messageCount > 10000) {
      score -= 0.2;
    }

    // Penalize unusual time patterns
    const hourCounts = new Map();
    for (const hour of profile.timePatterns) {
      hourCounts.set(hour, (hourCounts.get(hour) || 0) + 1);
    }

    const variance = this.calculateVariance(Array.from(hourCounts.values()));
    if (variance > 100) {
      score -= 0.1;
    }

    return Math.max(0, score);
  }

  private calculateVariance(values: number[]): number {
    const mean = values.reduce((sum, val) => sum + val, 0) / values.length;
    const squaredDiffs = values.map((val) => Math.pow(val - mean, 2));
    return squaredDiffs.reduce((sum, diff) => sum + diff, 0) / values.length;
  }
}

class NetworkSegmentation {
  private policy: SecurityPolicy;
  private segments: Map<string, string[]> = new Map();

  constructor(policy: SecurityPolicy) {
    this.policy = policy;
    this.initializeSegments();
  }

  private initializeSegments(): void {
    // Define network segments based on agent types
    this.segments.set("core", [
      "coder",
      "planner",
      "researcher",
      "reviewer",
      "tester",
    ]);
    this.segments.set("coordination", [
      "hierarchical-coordinator",
      "mesh-coordinator",
      "adaptive-coordinator",
    ]);
    this.segments.set("security", [
      "security-auditor",
      "penetration-tester",
      "encryption-specialist",
      "access-controller",
    ]);
    this.segments.set("infrastructure", [
      "devops-engineer",
      "cloud-architect",
      "container-orchestrator",
      "infrastructure-monitor",
    ]);
  }

  canCommunicate(fromAgentType: string, toAgentType: string): boolean {
    if (!this.policy.zeroTrust.networkSegmentation) {
      return true;
    }

    // Find segments for both agents
    const fromSegment = this.findAgentSegment(fromAgentType);
    const toSegment = this.findAgentSegment(toAgentType);

    // Allow communication within same segment
    if (fromSegment === toSegment) {
      return true;
    }

    // Define cross-segment communication rules
    const allowedCrossSegment = [
      ["core", "coordination"],
      ["coordination", "infrastructure"],
      ["security", "core"],
      ["security", "infrastructure"],
    ];

    return allowedCrossSegment.some(
      ([seg1, seg2]) =>
        (fromSegment === seg1 && toSegment === seg2) ||
        (fromSegment === seg2 && toSegment === seg1),
    );
  }

  private findAgentSegment(agentType: string): string | null {
    for (const [segment, types] of this.segments) {
      if (types.includes(agentType)) {
        return segment;
      }
    }
    return null;
  }
}