# Phase 4: Security & Zero Trust - Detailed Implementation (Weeks 7-8, 80 hours)

## Overview

Enterprise-grade security with Zero Trust architecture and ABAC.

## Week 1: Zero Trust Architecture (40 hours)

### Day 1-2: Device Verification (16 hours)

**Tasks:**
1. Create `backend/internal/security/device_verification.go`:
   - Device fingerprinting
   - Device registration
   - Device trust scoring
   - Anomaly detection

2. Implement device checks:
   - OS verification
   - Browser verification
   - Hardware verification
   - Location verification

3. Add device management:
   - Trusted devices list
   - Device revocation
   - Device rotation

### Day 3-4: Context Validation (16 hours)

**Tasks:**
1. Create `backend/internal/security/context_validation.go`:
   - Time-based validation
   - Location-based validation
   - Network-based validation
   - Behavior-based validation

2. Implement risk assessment:
   - Risk scoring
   - Adaptive authentication
   - Step-up authentication

3. Add continuous authentication:
   - Session monitoring
   - Anomaly detection
   - Automatic re-authentication

### Day 5: Testing & Validation (8 hours)

**Tasks:**
1. Write device verification tests
2. Write context validation tests
3. Test risk assessment
4. Test continuous auth
5. Verify security

## Week 2: ABAC & Encryption (40 hours)

### Day 1-2: ABAC Implementation (16 hours)

**Tasks:**
1. Create `backend/internal/security/abac.go`:
   - Attribute-based access control
   - Policy engine
   - Attribute evaluation
   - Decision caching

2. Define attributes:
   - User attributes (role, department, clearance)
   - Resource attributes (classification, owner)
   - Environment attributes (time, location, network)

3. Implement policies:
   - Policy language
   - Policy evaluation
   - Policy caching

### Day 3-4: Encryption & Secrets (16 hours)

**Tasks:**
1. Create `backend/internal/security/encryption.go`:
   - Encryption at rest
   - Encryption in transit
   - Key management
   - Key rotation

2. Implement secrets management:
   - Secrets vault integration
   - Secrets rotation
   - Audit logging

3. Add compliance logging:
   - Access logs
   - Change logs
   - Audit trail

### Day 5: Integration & Testing (8 hours)

**Tasks:**
1. Integrate ABAC with handlers
2. Integrate encryption with database
3. Write integration tests
4. Test compliance
5. Security audit

## Implementation Details

### Device Verification

```go
type DeviceVerification struct {
    DeviceID      string
    Fingerprint   string
    OS            string
    Browser       string
    TrustScore    float64
    LastSeen      time.Time
    IsVerified    bool
}

func (dv *DeviceVerification) Verify(ctx context.Context) error {
    // Verify device fingerprint
    // Check trust score
    // Update last seen
}
```

### ABAC Policy

```go
type ABACPolicy struct {
    ID        string
    Name      string
    Effect    string // "Allow" or "Deny"
    Principal string
    Action    string
    Resource  string
    Condition map[string]interface{}
}

func (p *ABACPolicy) Evaluate(ctx context.Context, attrs map[string]interface{}) bool {
    // Evaluate conditions
    // Return decision
}
```

### Encryption Configuration

```go
type EncryptionConfig struct {
    Algorithm   string // "AES-256-GCM"
    KeyProvider string // "vault" or "kms"
    RotationDays int
}
```

## Success Criteria

✅ Device verification working
✅ Context validation working
✅ ABAC policies enforced
✅ Encryption working
✅ Secrets managed
✅ Audit logging complete
✅ All tests passing

## Expected Results

- **Security:** Enterprise-grade Zero Trust
- **Compliance:** Audit trail for all access
- **Encryption:** All data encrypted
- **Access Control:** Fine-grained permissions

## Troubleshooting

**Issue:** Device verification failing
- Check fingerprinting logic
- Check device registration
- Review trust scoring

**Issue:** ABAC policies not enforced
- Check policy evaluation
- Check attribute mapping
- Review policy logic

**Issue:** Encryption overhead
- Check key caching
- Check algorithm efficiency
- Optimize encryption

## Next Phase

After Phase 4 complete:
- Move to Phase 5: Advanced AI & Agents
- Implement GraphRAG
- Add fine-tuning

