# Security Guide

## ⚠️ CRITICAL SECURITY NOTICE

**This library provides state synchronization but does NOT include built-in authentication, authorization, or encryption.**

**Risk Level: HIGH** - Multiple critical security gaps require external implementation before production deployment.

## 🚨 Security Model

### Current State

The CRDT-sync library operates with **ZERO security controls**:

- ❌ **No authentication** - Anyone can join any room
- ❌ **No authorization** - All room members have full read+write access
- ❌ **No encryption** - Data transmitted in plaintext over WebRTC/WebSocket
- ❌ **No input validation** - Accepts arbitrary data from peers
- ❌ **No rate limiting** - Vulnerable to DoS attacks

**This is a transport mechanism, NOT a security solution.**

### Security Responsibilities

| Responsibility | Library | Developer |
|----------------|---------|-----------|
| Authentication | ❌ | ✅ **REQUIRED** |
| Authorization | ❌ | ✅ **REQUIRED** |
| Encryption | ❌ | ✅ **REQUIRED** |
| Input Validation | ❌ | ✅ **REQUIRED** |
| Rate Limiting | ❌ | ✅ **REQUIRED** |
| Audit Logging | ❌ | ✅ **REQUIRED** |

## 🛡️ Required Security Controls

### 1. Transport Layer Security (TLS)

**CRITICAL**: Always use encrypted connections in production.

```typescript
// ✅ CORRECT - Secure WebSocket
const model = new MyModel({
  room: 'my-room',
  provider: {
    websocket: {
      url: 'wss://secure.myapp.com'  // WSS, not WS
    },
    webrtc: {
      signaling: ['wss://signal.myapp.com']  // WSS, not WS
    }
  }
});

// ❌ WRONG - Unencrypted (Default in code)
websocket: {
  url: 'ws://172.19.11.77:1234'  // INSECURE!
}
```

### 2. Authentication

Implement authentication BEFORE allowing room access.

```typescript
// Example secure wrapper (MUST IMPLEMENT)
class SecureRoomAccess {
  async joinRoom(credentials: UserCredentials, roomId: string) {
    // 1. Authenticate user
    const authToken = await authService.authenticate(credentials);

    // 2. Verify room access permission
    const hasAccess = await authService.checkRoomAccess(
      authToken,
      roomId
    );

    if (!hasAccess) {
      throw new Error('Unauthorized access to room');
    }

    // 3. Get short-lived room token
    const roomToken = await authService.getRoomToken(
      authToken,
      roomId,
      { expiresIn: '1h' }
    );

    // 4. Connect with secured credentials
    const model = new MyModel({
      room: roomId,
      provider: {
        websocket: {
          url: 'wss://secure.myapp.com',
          params: {
            auth: authToken,
            room_token: roomToken
          }
        }
      }
    });

    return model;
  }
}
```

### 3. Authorization

Control who can read/write data in rooms.

```typescript
// Server-side (WebSocket/Signaling server)
class RoomAuthorization {
  async authorizeOperation(
    userId: string,
    roomId: string,
    operation: 'read' | 'write' | 'delete'
  ): Promise<boolean> {
    const permissions = await db.getRoomPermissions(userId, roomId);

    return permissions.includes(operation);
  }

  async validateMessage(
    userId: string,
    roomId: string,
    message: YjsUpdate
  ): Promise<boolean> {
    // Check if user is allowed to write to this room
    const canWrite = await this.authorizeOperation(userId, roomId, 'write');

    if (!canWrite) {
      throw new UnauthorizedError('Write permission denied');
    }

    // Optionally: validate message structure
    return true;
  }
}
```

### 4. End-to-End Encryption

Encrypt data before syncing over the network.

```typescript
// Example E2EE wrapper
class EncryptedSyncModel<T> extends BaseSyncModel<T> {
  private cryptoKey: CryptoKey;

  async init(password: string, salt: Uint8Array) {
    // Derive encryption key from password
    const keyMaterial = await crypto.subtle.importKey(
      'raw',
      new TextEncoder().encode(password),
      'PBKDF2',
      false,
      ['deriveBits', 'deriveKey']
    );

    this.cryptoKey = await crypto.subtle.deriveKey(
      {
        name: 'PBKDF2',
        salt: salt,
        iterations: 100000,
        hash: 'SHA-256'
      },
      keyMaterial,
      { name: 'AES-GCM', length: 256 },
      true,
      ['encrypt', 'decrypt']
    );
  }

  async setValue(value: T): Promise<void> {
    // Encrypt before storing in Yjs
    const encrypted = await this.encrypt(JSON.stringify(value));
    super.setValue(encrypted as any);
  }

  getValue(): T {
    // Decrypt after retrieving from Yjs
    const encrypted = super.getValue();
    return this.decrypt(encrypted as any) as T;
  }

  private async encrypt(data: string): Promise<Uint8Array> {
    const iv = crypto.getRandomValues(new Uint8Array(12));
    const encrypted = await crypto.subtle.encrypt(
      { name: 'AES-GCM', iv },
      this.cryptoKey,
      new TextEncoder().encode(data)
    );

    // Prepend IV to encrypted data
    return new Uint8Array([...iv, ...new Uint8Array(encrypted)]);
  }

  private async decrypt(encrypted: Uint8Array): Promise<string> {
    const iv = encrypted.slice(0, 12);
    const data = encrypted.slice(12);

    const decrypted = await crypto.subtle.decrypt(
      { name: 'AES-GCM', iv },
      this.cryptoKey,
      data
    );

    return new TextDecoder().decode(decrypted);
  }
}
```

### 5. Input Validation & Sanitization

Validate all data to prevent injection attacks and DoS.

```typescript
// Example validated model
class ValidatedListModel<T> extends createListModel<T>({room: 'items'}) {
  private maxItems = 1000;
  private maxItemSize = 100 * 1024; // 100 KB
  private operationsPerMinute = 100;
  private operationCount = 0;
  private resetTime = Date.now() + 60000;

  @modelAction
  add(item: T): number {
    // Rate limiting
    if (Date.now() > this.resetTime) {
      this.operationCount = 0;
      this.resetTime = Date.now() + 60000;
    }

    if (this.operationCount++ >= this.operationsPerMinute) {
      throw new Error('Rate limit exceeded');
    }

    // Size limits
    if (this.size >= this.maxItems) {
      throw new Error('Maximum items limit reached');
    }

    const itemSize = JSON.stringify(item).length;
    if (itemSize > this.maxItemSize) {
      throw new Error('Item size exceeds maximum');
    }

    // Type validation
    if (typeof item !== 'object' || item === null) {
      throw new Error('Invalid item type');
    }

    // Sanitize strings to prevent XSS
    const sanitized = this.sanitize(item);

    return super.add(sanitized);
  }

  private sanitize(obj: any): any {
    if (typeof obj === 'string') {
      // Basic XSS prevention
      return obj
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;')
        .replace(/"/g, '&quot;')
        .replace(/'/g, '&#x27;')
        .replace(/\//g, '&#x2F;');
    }

    if (typeof obj === 'object' && obj !== null) {
      const sanitized: any = Array.isArray(obj) ? [] : {};
      for (const key in obj) {
        sanitized[key] = this.sanitize(obj[key]);
      }
      return sanitized;
    }

    return obj;
  }
}
```

### 6. Audit Logging

Log all security-relevant events for forensics and monitoring.

```typescript
interface AuditEvent {
  timestamp: number;
  userId: string;
  action: string;
  resourceId: string;
  success: boolean;
  details?: Record<string, any>;
}

class AuditedSyncProvider extends SimpleSyncProvider {
  private async logEvent(event: AuditEvent): Promise<void> {
    await fetch('/api/audit', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${this.authToken}`
      },
      body: JSON.stringify(event)
    });
  }

  async connect(): Promise<void> {
    try {
      await super.connect();

      await this.logEvent({
        timestamp: Date.now(),
        userId: this.getCurrentUserId(),
        action: 'connect',
        resourceId: this.room,
        success: true
      });
    } catch (error) {
      await this.logEvent({
        timestamp: Date.now(),
        userId: this.getCurrentUserId(),
        action: 'connect',
        resourceId: this.room,
        success: false,
        details: { error: error.message }
      });
      throw error;
    }
  }
}
```

## 🎯 Critical Vulnerabilities

### V1: Room Hijacking (CVSS 9.1)

**Risk**: Anyone can join any room by guessing/discovering room names.

**Attack**:
```typescript
// Attacker joins victim's room
const stolen = new SimpleSyncProvider({
  room: 'user-123-private-data',  // Guessed room name
  ydoc: attackerDoc
});
// Now has full access to all data
```

**Mitigation**:
- Use cryptographically random room IDs (UUIDs)
- Implement server-side room access validation
- Use authenticated WebSocket connections
- Never expose room names in URLs or logs

### V2: Man-in-the-Middle (CVSS 9.3)

**Risk**: Unencrypted connections allow data interception.

**Attack**:
```bash
# Attacker on same network using Wireshark
wireshark -i en0 -f "tcp port 4444"
# Can see all unencrypted signaling and data
```

**Mitigation**:
- **ALWAYS** use `wss://` instead of `ws://`
- Deploy with HTTPS/TLS 1.3+
- Use HSTS headers
- Implement certificate pinning for mobile apps

### V3: Data Exfiltration (CVSS 9.1)

**Risk**: No access control means any peer can read all data.

**Mitigation**:
- Implement authentication before room access
- Use end-to-end encryption
- Segment data by access levels
- Monitor for suspicious access patterns

### V4: Denial of Service (CVSS 6.8)

**Risk**: Malicious peer can flood updates or insert large objects.

**Attack**:
```typescript
// Flood attack
setInterval(() => {
  model.create({ huge: 'x'.repeat(1000000) });
}, 10);
```

**Mitigation**:
- Implement rate limiting (operations per minute)
- Set maximum document size limits
- Set maximum array/collection lengths
- Monitor and block abusive peers

### V5: Cross-Site WebSocket Hijacking (CVSS 6.1)

**Risk**: CSWSH attacks if WebSocket connections don't validate origin.

**Mitigation (Server-side)**:
```typescript
// WebSocket server
server.on('connection', (ws, request) => {
  const origin = request.headers.origin;
  const allowedOrigins = ['https://myapp.com', 'https://www.myapp.com'];

  if (!allowedOrigins.includes(origin)) {
    ws.close(1008, 'Unauthorized origin');
    return;
  }

  // Also validate CSRF token
  const token = new URL(request.url, 'wss://dummy').searchParams.get('csrf');
  if (!validateCsrfToken(token)) {
    ws.close(1008, 'Invalid CSRF token');
    return;
  }
});
```

## 🏢 Compliance Considerations

### GDPR (General Data Protection Regulation)

**Current Compliance Status: NON-COMPLIANT**

Required Controls:
- ❌ No consent mechanism for data sharing with peers
- ❌ Cannot fulfill "right to erasure" (CRDT history is immutable)
- ❌ No data retention policies
- ❌ Cross-border data transfer not controlled
- ❌ No data breach notification capability

**Actions Required**:
1. Obtain explicit consent before sharing user data in rooms
2. Implement data export functionality (portability)
3. Document legal basis for processing
4. Add data processing agreements with room participants
5. Note: CRDT "right to erasure" conflict requires legal guidance

### HIPAA (Healthcare)

**Current Compliance Status: NON-COMPLIANT**

Missing Controls:
- ❌ No encryption at rest or in transit (application layer)
- ❌ No access controls (authentication/authorization)
- ❌ No audit logging
- ❌ No Business Associate Agreements
- ❌ No automatic logoff
- ❌ No emergency access procedures

**DO NOT USE FOR PHI WITHOUT EXTENSIVE ADDITIONAL SECURITY.**

### SOC 2

**Current Compliance Status: NON-COMPLIANT**

Missing Trust Service Criteria:
- ❌ Security: No authentication, no encryption
- ⚠️ Availability: DoS vulnerable
- ❌ Processing Integrity: No validation, no checksums
- ❌ Confidentiality: No encryption, data leakage possible
- ❌ Privacy: No privacy controls

### PCI DSS (Payment Card Industry)

**Current Compliance Status: NON-COMPLIANT**

**DO NOT STORE OR TRANSMIT PAYMENT CARD DATA** using this library without implementing:
- ✅ Requirement 3: Protect stored cardholder data (encryption)
- ✅ Requirement 4: Encrypt transmission (TLS)
- ✅ Requirement 8: Authentication and access control
- ✅ Requirement 10: Track and monitor access (audit logging)

## ✅ Production Deployment Checklist

### Infrastructure Security

- [ ] Deploy signaling server with TLS 1.3+
- [ ] Use authenticated TURN servers only
- [ ] Configure reverse proxy (nginx/Cloudflare)
- [ ] Enable DDoS protection
- [ ] Set security headers (CSP, HSTS, X-Frame-Options)
- [ ] Implement Web Application Firewall (WAF)
- [ ] Configure rate limiting (per-IP, per-room)
- [ ] Enable audit logging for all connections
- [ ] Set up SIEM for security monitoring
- [ ] Regular security updates and patching

### Application Security

- [ ] Implement authentication for all users
- [ ] Add authorization for room access
- [ ] Enable end-to-end encryption
- [ ] Validate and sanitize all inputs
- [ ] Implement rate limiting on operations
- [ ] Add XSS protection (Content Security Policy)
- [ ] Configure CORS properly
- [ ] Use secure random room IDs (UUIDs)
- [ ] Implement session timeout
- [ ] Add comprehensive error handling

### Monitoring & Incident Response

- [ ] Security event monitoring
- [ ] Intrusion detection system (IDS)
- [ ] Automated alerts for suspicious activity
- [ ] Incident response plan documented
- [ ] Regular security audits
- [ ] Penetration testing conducted
- [ ] Backup and recovery procedures
- [ ] Data breach notification process

## 📚 Additional Resources

- [OWASP Top 10](https://owasp.org/www-project-top-ten/)
- [WebRTC Security](https://webrtc-security.github.io/)
- [WebSocket Security](https://owasp.org/www-community/vulnerabilities/WebSocket_security)
- [CRDT Security Considerations](https://arxiv.org/abs/2012.00472)

## 🚨 Reporting Security Issues

**DO NOT** open public GitHub issues for security vulnerabilities.

Report security issues privately to:
- Email: security@networkoptix.com
- PGP Key: [Link to PGP key]

Include:
- Description of vulnerability
- Steps to reproduce
- Potential impact
- Suggested mitigation (if any)

We aim to respond within 48 hours.

---

**Remember: Security is a shared responsibility. This library handles synchronization; you handle security.**
