# Edge-Net Relay Security Audit Report

**Date**: 2026-01-03
**Auditor**: Code Review Agent
**Component**: Edge-Net WebSocket Relay Server (`/relay/index.js`)
**Version**: v0.1.0

---

## Executive Summary

A comprehensive security audit was conducted on the Edge-Net relay server, focusing on authentication, authorization, and protection against common attack vectors. The relay implements **strong security controls** for task assignment and credit distribution, with **Firestore-backed QDAG (Quantum Directed Acyclic Graph) ledger** as the source of truth.

**Overall Security Rating**: ✅ **GOOD** (with minor recommendations)

### Key Findings

| Category | Status | Details |
|----------|--------|---------|
| Task Completion Spoofing | ✅ **SECURE** | Protected by assignment tracking |
| Replay Attacks | ✅ **SECURE** | Protected by completed tasks set |
| Credit Self-Reporting | ✅ **SECURE** | Disabled - relay-only crediting |
| Public Key Spoofing | ⚠️ **MOSTLY SECURE** | See recommendations |
| Rate Limiting | ✅ **IMPLEMENTED** | Per-node message throttling |
| Message Size Limits | ✅ **IMPLEMENTED** | 64KB max payload |
| Connection Limits | ✅ **IMPLEMENTED** | 5 connections per IP |
| Origin Validation | ✅ **IMPLEMENTED** | CORS whitelist |

---

## Security Architecture

### 1. QDAG Ledger (Source of Truth)

**Implementation**: Lines 66-142

```javascript
// Firestore-backed persistent credit ledger
const ledgerCollection = firestore.collection('edge-net-qdag');

// Credits ONLY increase via verified task completions
async function creditAccount(publicKey, amount, taskId) {
  const ledger = await loadLedger(publicKey);
  ledger.earned += amount;
  ledger.tasksCompleted += 1;
  await saveLedger(publicKey, ledger);
}
```

**Security Properties**:
- ✅ Credits keyed by **public key** (identity-based, not node-based)
- ✅ Persistent across sessions (Firestore)
- ✅ Server-side only (clients cannot modify)
- ✅ Atomic operations with in-memory cache

---

## Attack Vector Analysis

### 🔴 Attack Vector 1: Task Completion Spoofing

**Description**: Malicious node tries to complete tasks not assigned to them.

**Protection Mechanism** (Lines 61-64, 222-229, 411-423):

```javascript
// Track assigned tasks with assignment metadata
const assignedTasks = new Map(); // taskId -> { assignedTo, submitter, maxCredits }

// On task assignment (lines 222-229)
assignedTasks.set(task.id, {
  assignedTo: targetNodeId,
  assignedToPublicKey: targetWs.publicKey,
  submitter: task.submitter,
  maxCredits: task.maxCredits,
  assignedAt: Date.now(),
});

// On task completion (lines 411-423)
const assignment = assignedTasks.get(taskId);
if (!assignment) {
  console.warn(`Task ${taskId} not found or expired`);
  ws.send(JSON.stringify({ type: 'error', message: 'Task not found or expired' }));
  break;
}

if (assignment.assignedTo !== nodeId) {
  console.warn(`Task ${taskId} assigned to ${assignment.assignedTo}, not ${nodeId} - SPOOFING ATTEMPT`);
  ws.send(JSON.stringify({ type: 'error', message: 'Task not assigned to you' }));
  break;
}
```

**Security Assessment**: ✅ **SECURE**

- Assignment tracked with node ID verification
- Only assigned node can complete task
- Clear error messages for debugging (but could be more generic for production)

**Test Coverage**: `relay-security.test.ts` - "Task Completion Spoofing" suite

---

### 🔴 Attack Vector 2: Replay Attacks

**Description**: Malicious node tries to complete the same task multiple times to earn duplicate credits.

**Protection Mechanism** (Lines 64, 425-430, 441):

```javascript
const completedTasks = new Set(); // Prevent double completion

// On task completion (lines 425-430)
if (completedTasks.has(taskId)) {
  console.warn(`Task ${taskId} already completed - REPLAY ATTEMPT from ${nodeId}`);
  ws.send(JSON.stringify({ type: 'error', message: 'Task already completed' }));
  break;
}

// Mark completed BEFORE crediting (line 441)
completedTasks.add(taskId);
assignedTasks.delete(taskId);
```

**Security Assessment**: ✅ **SECURE**

- Tasks marked complete **before** crediting (prevents race conditions)
- Permanent replay prevention (Set-based tracking)
- Assignment deleted after completion

**Potential Issue**: ⚠️ `completedTasks` Set grows unbounded

**Recommendation**: Implement periodic cleanup for old completed tasks:

```javascript
// Cleanup completed tasks older than 24 hours
setInterval(() => {
  const CLEANUP_AGE = 24 * 60 * 60 * 1000; // 24 hours
  // Track completion timestamps and remove old entries
}, 60 * 60 * 1000); // Every hour
```

**Test Coverage**: `relay-security.test.ts` - "Replay Attacks" suite

---

### 🔴 Attack Vector 3: Credit Self-Reporting

**Description**: Malicious client tries to submit their own credit values to inflate balance.

**Protection Mechanism** (Lines 612-622):

```javascript
case 'ledger_update':
  // DEPRECATED: Clients cannot self-report credits
  {
    console.warn(`[QDAG] REJECTED ledger_update from ${nodeId} - clients cannot self-report credits`);
    ws.send(JSON.stringify({
      type: 'error',
      message: 'Credit self-reporting disabled. Credits earned via task completions only.',
    }));
  }
  break;
```

**Security Assessment**: ✅ **SECURE**

- `ledger_update` messages explicitly rejected
- Only `creditAccount()` function can increase earned credits
- `creditAccount()` only called after verified task completion (lines 450-451)
- Firestore ledger is source of truth

**Additional Security**:
- `ledger_sync` is **read-only** (lines 570-610) - returns balance from Firestore
- No client-submitted credit values accepted anywhere

**Test Coverage**: `relay-security.test.ts` - "Credit Self-Reporting" suite

---

### 🔴 Attack Vector 4: Public Key Spoofing

**Description**: Malicious node tries to use another user's public key to claim their credits or identity.

**Protection Mechanism**: Lines 360-366, 432-438, 584

**Current Implementation**:

```javascript
// On registration (lines 360-366)
if (message.publicKey) {
  ws.publicKey = message.publicKey;
  console.log(`Node registered: ${nodeId} with identity ${message.publicKey.slice(0, 16)}...`);
}

// On task completion (lines 432-438)
const processorPublicKey = assignment.assignedToPublicKey || ws.publicKey;
if (!processorPublicKey) {
  ws.send(JSON.stringify({ type: 'error', message: 'Public key required for credit' }));
  break;
}

// Credits go to the PUBLIC KEY stored in assignment
await creditAccount(processorPublicKey, rewardRuv, taskId);
```

**Security Assessment**: ⚠️ **MOSTLY SECURE** (with caveats)

**What IS Secure**:
- ✅ Credits keyed by public key (same identity = same balance everywhere)
- ✅ Public key stored at assignment time (prevents mid-flight changes)
- ✅ Credits awarded to `assignment.assignedToPublicKey` (not current `ws.publicKey`)
- ✅ Multiple nodes can share public key (multi-device support by design)

**What IS NOT Fully Protected**:
- ⚠️ **No cryptographic signature verification** (Line 281-286)

```javascript
// CURRENT: Placeholder validation
function validateSignature(nodeId, message, signature, publicKey) {
  // In production, verify Ed25519 signature from PiKey
  // For now, accept if nodeId matches registered node
  return nodes.has(nodeId);
}
```

- ⚠️ Clients can **claim** any public key without proving ownership
- ⚠️ This allows "read-only spoofing" - checking another user's balance

**Impact Assessment**:

| Scenario | Risk Level | Impact |
|----------|-----------|--------|
| Checking another user's balance | 🟡 **LOW** | Privacy leak, but no financial impact |
| Claiming another user's public key at registration | 🟡 **LOW** | Cannot steal existing credits (assigned at task time) |
| Earning credits to someone else's key | 🟡 **LOW** | Self-harm (attacker works for victim's benefit) |
| Completing tasks assigned to victim | 🔴 **NONE** | Protected by `assignedTo` node ID check |

**Recommendations**:

1. **Implement Ed25519 Signature Verification** (CRITICAL for production):

```javascript
import { verify } from '@noble/ed25519';

async function validateSignature(message, signature, publicKey) {
  try {
    const msgHash = createHash('sha256').update(JSON.stringify(message)).digest();
    return await verify(signature, msgHash, publicKey);
  } catch {
    return false;
  }
}

// Require signature on sensitive operations
case 'task_complete':
  if (!message.signature || !validateSignature(message, message.signature, ws.publicKey)) {
    ws.send(JSON.stringify({ type: 'error', message: 'Invalid signature' }));
    break;
  }
  // ... rest of task completion logic
```

2. **Add Challenge-Response on Registration**:

```javascript
case 'register':
  // Send challenge
  const challenge = randomBytes(32).toString('hex');
  challenges.set(nodeId, challenge);
  ws.send(JSON.stringify({
    type: 'challenge',
    challenge: challenge,
  }));
  break;

case 'challenge_response':
  const challenge = challenges.get(nodeId);
  if (!validateSignature({ challenge }, message.signature, message.publicKey)) {
    ws.close(4003, 'Invalid signature');
    break;
  }
  // Complete registration...
```

3. **Rate-limit balance queries** to prevent enumeration attacks:

```javascript
case 'ledger_sync':
  if (!checkRateLimit(`${nodeId}-ledger-sync`, 10, 60000)) { // 10 per minute
    ws.send(JSON.stringify({ type: 'error', message: 'Balance query rate limit' }));
    break;
  }
```

**Test Coverage**: `relay-security.test.ts` - "Public Key Spoofing" suite

---

## Additional Security Features

### 5. Rate Limiting

**Implementation**: Lines 45-46, 265-279, 346-350

```javascript
const rateLimits = new Map();
const RATE_LIMIT_MAX = 100; // max messages per window
const RATE_LIMIT_WINDOW = 60000; // 1 minute

function checkRateLimit(nodeId) {
  const now = Date.now();
  const limit = rateLimits.get(nodeId) || { count: 0, windowStart: now };

  if (now - limit.windowStart > RATE_LIMIT_WINDOW) {
    limit.count = 0;
    limit.windowStart = now;
  }

  limit.count++;
  rateLimits.set(nodeId, limit);

  return limit.count <= RATE_LIMIT_MAX;
}
```

**Security Assessment**: ✅ **GOOD**

- Per-node rate limiting (not global)
- Sliding window implementation
- Enforced after registration

**Recommendations**:
- ✅ Consider adaptive rate limits based on node reputation
- ✅ Add separate limits for expensive operations (task_submit, ledger_sync)

---

### 6. Message Size Limits

**Implementation**: Lines 21, 318, 338-342

```javascript
const MAX_MESSAGE_SIZE = 64 * 1024; // 64KB

ws._maxPayload = MAX_MESSAGE_SIZE;

if (data.length > MAX_MESSAGE_SIZE) {
  ws.send(JSON.stringify({ type: 'error', message: 'Message too large' }));
  return;
}
```

**Security Assessment**: ✅ **GOOD**

- Prevents DoS via large payloads
- Enforced at both WebSocket and application layer
- 64KB is reasonable for control messages

---

### 7. Connection Limits

**Implementation**: Lines 22, 308-315, 671-677

```javascript
const MAX_CONNECTIONS_PER_IP = 5;
const ipConnections = new Map();

// On connection
const ipCount = ipConnections.get(clientIP) || 0;
if (ipCount >= MAX_CONNECTIONS_PER_IP) {
  console.log(`Rejected connection: too many from ${clientIP}`);
  ws.close(4002, 'Too many connections');
  return;
}
ipConnections.set(clientIP, ipCount + 1);

// On close
const currentCount = ipConnections.get(clientIP) || 1;
if (currentCount <= 1) {
  ipConnections.delete(clientIP);
} else {
  ipConnections.set(clientIP, currentCount - 1);
}
```

**Security Assessment**: ✅ **GOOD**

- Prevents connection flooding from single IP
- Properly tracks connection/disconnection
- 5 connections is reasonable for multi-device scenarios

**Potential Issue**: ⚠️ Does not defend against distributed attacks (multiple IPs)

**Recommendations**:
- Add global connection limit (e.g., max 1000 total connections)
- Implement connection rate limiting (max N new connections per minute per IP)

---

### 8. Origin Validation

**Implementation**: Lines 27-37, 255-263, 301-306

```javascript
const ALLOWED_ORIGINS = new Set([
  'http://localhost:3000',
  'https://edge-net.ruv.io',
  // ... other allowed origins
]);

function isOriginAllowed(origin) {
  if (!origin) return true; // Allow Node.js connections
  if (ALLOWED_ORIGINS.has(origin)) return true;
  if (origin.startsWith('http://localhost:')) return true; // Dev mode
  return false;
}

if (!isOriginAllowed(origin)) {
  ws.close(4001, 'Unauthorized origin');
  return;
}
```

**Security Assessment**: ✅ **GOOD** for browser connections

**Recommendations**:
- ⚠️ `if (!origin) return true` allows **any** non-browser client (CLI, scripts)
- Consider requiring API key or authentication for non-browser connections:

```javascript
function isOriginAllowed(origin, headers) {
  if (!origin) {
    // Non-browser connection - require API key
    const apiKey = headers['x-api-key'];
    return apiKey && validateAPIKey(apiKey);
  }
  return ALLOWED_ORIGINS.has(origin) || origin.startsWith('http://localhost:');
}
```

---

### 9. Task Expiration

**Implementation**: Lines 243-253

```javascript
// Cleanup old assigned tasks (expire after 5 minutes)
setInterval(() => {
  const now = Date.now();
  const TASK_TIMEOUT = 5 * 60 * 1000; // 5 minutes
  for (const [taskId, task] of assignedTasks) {
    if (now - task.assignedAt > TASK_TIMEOUT) {
      assignedTasks.delete(taskId);
      console.log(`Task ${taskId} expired (not completed in time)`);
    }
  }
}, 60000); // Check every minute
```

**Security Assessment**: ✅ **GOOD**

- Prevents stale task assignments
- 5-minute timeout is reasonable
- Automatically cleans up abandoned tasks

**Recommendation**: ⚠️ Consider re-queuing expired tasks:

```javascript
if (now - task.assignedAt > TASK_TIMEOUT) {
  assignedTasks.delete(taskId);

  // Re-queue task if original submitter still connected
  if (nodes.has(task.submitter)) {
    taskQueue.push({
      id: taskId,
      submitter: task.submitter,
      // ... task details
    });
    console.log(`Task ${taskId} re-queued after timeout`);
  }
}
```

---

### 10. Heartbeat Timeout

**Implementation**: Lines 25, 320-329

```javascript
const CONNECTION_TIMEOUT = 30000; // 30s heartbeat timeout

let heartbeatTimeout;
const resetHeartbeat = () => {
  clearTimeout(heartbeatTimeout);
  heartbeatTimeout = setTimeout(() => {
    console.log(`Node ${nodeId} timed out`);
    ws.terminate();
  }, CONNECTION_TIMEOUT);
};
resetHeartbeat();

// Reset on any message
ws.on('message', async (data) => {
  resetHeartbeat();
  // ...
});
```

**Security Assessment**: ✅ **GOOD**

- Prevents zombie connections
- 30-second timeout with implicit heartbeat (any message resets)
- Explicit heartbeat message type also supported (lines 651-657)

---

## Remaining Vulnerabilities

### 🔴 CRITICAL (Production Blockers)

1. **No Cryptographic Signature Verification**
   - **Impact**: Cannot prove public key ownership
   - **Mitigation**: Implement Ed25519 signature validation (see recommendations above)
   - **Priority**: **CRITICAL** for production

### 🟡 MEDIUM (Should Address)

2. **Unbounded `completedTasks` Set Growth**
   - **Impact**: Memory leak over time
   - **Mitigation**: Implement periodic cleanup of old completed tasks
   - **Priority**: **MEDIUM**

3. **No Global Connection Limit**
   - **Impact**: Distributed attack from many IPs could exhaust resources
   - **Mitigation**: Add global max connection limit
   - **Priority**: **MEDIUM**

4. **Permissive Non-Browser Access**
   - **Impact**: Any script can connect without authentication
   - **Mitigation**: Require API key for non-browser connections
   - **Priority**: **MEDIUM** (depends on use case)

### 🟢 LOW (Nice to Have)

5. **Error Messages Reveal Internal State**
   - **Impact**: Attackers can infer system behavior from detailed errors
   - **Mitigation**: Use generic error messages in production, detailed in logs
   - **Priority**: **LOW**

6. **No Firestore Access Control Validation**
   - **Impact**: Assumes Firestore security rules are correctly configured
   - **Mitigation**: Document required Firestore security rules
   - **Priority**: **LOW** (infrastructure concern)

---

## Firestore Security Rules Required

The relay assumes these Firestore security rules are in place:

```javascript
rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /edge-net-qdag/{publicKey} {
      // Only server (via Admin SDK) can write
      allow read: if false;  // Not public
      allow write: if false; // Server-only
    }
  }
}
```

**Validation**: ⚠️ Not tested in this audit - infrastructure team should verify.

---

## Test Coverage Summary

Created comprehensive security test suite: `/tests/relay-security.test.ts`

**Test Suites**:
1. ✅ Task Completion Spoofing (2 tests)
2. ✅ Replay Attacks (1 test)
3. ✅ Credit Self-Reporting (2 tests)
4. ✅ Public Key Spoofing (2 tests)
5. ✅ Rate Limiting (1 test)
6. ✅ Message Size Limits (1 test)
7. ✅ Connection Limits (1 test)
8. ✅ Task Expiration (1 test)
9. ✅ Combined Attack Scenario (1 test)

**Total**: 12 security tests

**To Run Tests**:
```bash
cd /workspaces/ruvector/examples/edge-net
npm install --save-dev @jest/globals ws @types/ws
npm test tests/relay-security.test.ts
```

---

## Recommendations Summary

### Immediate (Before Production)

1. ✅ **Implement Ed25519 signature verification** for public key ownership
2. ✅ **Add challenge-response** on node registration
3. ✅ **Implement completedTasks cleanup** to prevent memory leak

### Short-term (1-2 weeks)

4. ✅ **Add global connection limit** (e.g., 1000 max total)
5. ✅ **Require API keys** for non-browser connections
6. ✅ **Add separate rate limits** for expensive operations
7. ✅ **Rate-limit balance queries** to prevent enumeration

### Long-term (1-3 months)

8. ✅ **Implement reputation-based rate limiting**
9. ✅ **Add connection rate limiting** (per IP)
10. ✅ **Use generic error messages** in production
11. ✅ **Document Firestore security rules** and validate configuration
12. ✅ **Add metrics and monitoring** for attack detection

---

## Conclusion

The Edge-Net relay server demonstrates **strong security fundamentals** with excellent protection against:
- ✅ Task completion spoofing
- ✅ Replay attacks
- ✅ Credit self-reporting
- ✅ Basic DoS attacks

**The QDAG ledger architecture is well-designed** with Firestore as source of truth and server-side-only crediting.

**Primary concern**: Lack of cryptographic signature verification means public key ownership is not proven. This is acceptable for testing/development but **MUST** be implemented before production deployment.

**Overall Assessment**: System is secure for testing/development. Implement critical recommendations before production.

---

**Audit Completed**: 2026-01-03
**Next Review**: After signature verification implementation