# Security Guide

Comprehensive security documentation for the Impersonator Smart Wallet system.

## Security Overview

The Impersonator system implements multiple layers of security to protect user data and prevent attacks:

1. **Encryption Layer** - Encrypted storage for sensitive data
2. **Validation Layer** - Comprehensive input validation
3. **Access Control Layer** - Owner verification and authorization
4. **Rate Limiting Layer** - DoS attack prevention
5. **Replay Protection** - Message and transaction replay prevention

## Security Features

### 1. Encrypted Storage

All sensitive data is encrypted before storage using AES-GCM encryption.

**Implementation:**
- AES-GCM encryption with 256-bit keys
- PBKDF2 key derivation (100,000 iterations)
- Session-based encryption keys
- Automatic encryption/decryption

**Usage:**
```typescript
import { SecureStorage } from "@/utils/encryption";

const storage = new SecureStorage();
await storage.setItem("wallets", JSON.stringify(wallets));
```

**What's Encrypted:**
- Wallet configurations
- Transaction data
- Owner information
- Threshold settings

### 2. Input Validation

All user inputs are validated before processing.

**Address Validation:**
```typescript
import { validateAddress } from "@/utils/security";

const validation = validateAddress(address);
if (!validation.valid) {
  // Handle invalid address
}
```

**Transaction Validation:**
```typescript
import { validateTransactionRequest } from "@/utils/security";

const validation = validateTransactionRequest(tx);
if (!validation.valid) {
  console.error(validation.errors);
}
```

**Validation Checks:**
- Address format and checksum
- Network ID support
- Transaction data format
- Value limits (max 1M ETH)
- Gas limit bounds (21k - 10M)
- Data size limits (max 10KB)

### 3. Access Control

All sensitive operations require authorization.

**Owner Verification:**
```typescript
// Before adding owner
const isOwner = activeWallet.owners.some(
  o => o.toLowerCase() === callerAddress.toLowerCase()
);
if (!isOwner) {
  throw new Error("Unauthorized");
}
```

**Threshold Validation:**
```typescript
// Before removing owner
if (newOwners.length < threshold) {
  throw new Error("Threshold would exceed owner count");
}
```

**Protected Operations:**
- Adding/removing owners
- Updating threshold
- Approving transactions
- Executing transactions

### 4. Rate Limiting

Rate limiting prevents DoS attacks and abuse.

**Implementation:**
```typescript
import { RateLimiter } from "@/utils/security";

const limiter = new RateLimiter(10, 60000); // 10 requests per minute
if (!limiter.checkLimit(userAddress)) {
  throw new Error("Rate limit exceeded");
}
```

**Limits:**
- Default: 10 requests per minute per address
- Configurable per use case
- Automatic cleanup of old entries

### 5. Replay Protection

Prevents replay attacks on messages and transactions.

**Message Replay Protection:**
- Timestamp-based validation
- 1-second replay window
- Message ID tracking
- Automatic cleanup

**Transaction Replay Protection:**
- Nonce management
- Transaction deduplication
- Transaction expiration (1 hour)
- Hash-based duplicate detection

### 6. Nonce Management

Automatic nonce management prevents transaction conflicts.

**Implementation:**
```typescript
import { NonceManager } from "@/utils/security";

const nonceManager = new NonceManager(provider);
const nonce = await nonceManager.getNextNonce(address);
```

**Features:**
- Automatic nonce tracking
- On-chain nonce synchronization
- Nonce refresh after execution
- Per-address nonce management

## Security Best Practices

### For Developers

#### 1. Always Validate Input

```typescript
// ✅ Good
const validation = validateAddress(address);
if (!validation.valid) {
  throw new Error(validation.error);
}

// ❌ Bad
const address = userInput; // No validation
```

#### 2. Use Secure Storage

```typescript
// ✅ Good
const storage = new SecureStorage();
await storage.setItem("data", JSON.stringify(sensitiveData));

// ❌ Bad
localStorage.setItem("data", JSON.stringify(sensitiveData));
```

#### 3. Check Authorization

```typescript
// ✅ Good
if (!isOwner(callerAddress)) {
  throw new Error("Unauthorized");
}

// ❌ Bad
// No authorization check
```

#### 4. Handle Errors Securely

```typescript
// ✅ Good
try {
  await operation();
} catch (error: any) {
  monitoring.error("Operation failed", error);
  // Don't expose sensitive error details
  throw new Error("Operation failed");
}

// ❌ Bad
catch (error) {
  console.error(error); // May expose sensitive info
}
```

#### 5. Use Rate Limiting

```typescript
// ✅ Good
if (!rateLimiter.checkLimit(userAddress)) {
  throw new Error("Rate limit exceeded");
}

// ❌ Bad
// No rate limiting
```

### For Users

#### 1. Verify Addresses

- Always verify addresses before transactions
- Use checksummed addresses
- Double-check recipient addresses

#### 2. Review Transactions

- Review all transaction details
- Verify gas estimates
- Check transaction data

#### 3. Protect Private Keys

- Never share private keys
- Use hardware wallets when possible
- Enable multi-sig for large wallets

#### 4. Monitor Activity

- Regularly check transaction history
- Monitor for unauthorized approvals
- Review wallet configurations

## Security Architecture

### Encryption Flow

```
User Data
    │
    ▼
Input Validation
    │
    ▼
Encryption (AES-GCM)
    │
    ▼
Encrypted Storage
    │
    ▼
Decryption (on read)
    │
    ▼
Validated Output
```

### Validation Flow

```
User Input
    │
    ▼
Format Validation
    │
    ▼
Type Validation
    │
    ▼
Range Validation
    │
    ▼
Business Logic Validation
    │
    ▼
Sanitization
    │
    ▼
Processed Input
```

### Authorization Flow

```
Operation Request
    │
    ▼
Extract Caller Address
    │
    ▼
Verify Owner Status
    │
    ▼
Check Threshold
    │
    ▼
Verify Permissions
    │
    ▼
Execute Operation
```

## Security Testing

### Running Security Tests

```bash
# Run all security tests
pnpm test:security

# Run specific security test
pnpm test __tests__/security.test.ts
```

### Security Test Coverage

- ✅ Address validation
- ✅ Transaction validation
- ✅ Encryption/decryption
- ✅ Rate limiting
- ✅ Nonce management
- ✅ Replay protection
- ✅ Access control

## Security Audit

A comprehensive security audit has been conducted. See:
- `SECURITY_AUDIT.md` - Full security audit
- `SECURITY_FIXES.md` - Security fixes implemented
- `SECURITY_SUMMARY.md` - Executive summary

### Audit Results

**Status:** ✅ All critical vulnerabilities addressed

**Security Posture:** 🟢 Low Risk (down from 🔴 High Risk)

**Key Improvements:**
- Encrypted storage implemented
- Comprehensive validation added
- Access control implemented
- Replay protection active
- Rate limiting enforced

## Incident Response

### Security Incident Procedure

1. **Identify** - Detect and confirm security incident
2. **Contain** - Isolate affected systems
3. **Assess** - Evaluate impact and scope
4. **Remediate** - Fix vulnerabilities
5. **Document** - Record incident and response
6. **Notify** - Inform affected users if necessary

### Reporting Security Issues

If you discover a security vulnerability:

1. **DO NOT** open a public issue
2. Email security team directly
3. Provide detailed information
4. Allow time for fix before disclosure

## Security Checklist

### Development Checklist

- [ ] All inputs validated
- [ ] Sensitive data encrypted
- [ ] Authorization checks in place
- [ ] Rate limiting implemented
- [ ] Error handling secure
- [ ] No sensitive data in logs
- [ ] Dependencies up to date
- [ ] Security tests passing

### Deployment Checklist

- [ ] Security audit completed
- [ ] All tests passing
- [ ] Error tracking configured
- [ ] Monitoring active
- [ ] HTTPS enforced
- [ ] Security headers set
- [ ] Backup procedures ready
- [ ] Incident response plan ready

## Security Resources

- [OWASP Top 10](https://owasp.org/www-project-top-ten/)
- [Ethereum Security Best Practices](https://consensys.github.io/smart-contract-best-practices/)
- [Web3 Security](https://web3security.dev/)
- [Smart Contract Security](https://smartcontractsecurity.github.io/)

## Security Updates

Security is an ongoing process. Regular updates include:
- Dependency updates
- Security patches
- New security features
- Improved validation
- Enhanced monitoring

Stay updated by:
- Monitoring security advisories
- Reviewing changelogs
- Running security audits
- Keeping dependencies current