# ADR 003: Security Roadmap

## Status

Proposed

## Context

As we move from a demonstration/example service to a production-ready system, we need to implement comprehensive security features. This ADR outlines the security roadmap and prioritization.

## Current State

### Implemented Security Features

- ✅ Input validation
- ✅ Type-safe error handling
- ✅ Dependency scanning (cargo-audit)
- ✅ No hardcoded secrets
- ✅ Structured logging
- ✅ SBOM generation

### Missing Security Features

- ❌ Authentication
- ❌ Authorization
- ❌ Rate limiting
- ❌ Request signing
- ❌ Encryption at rest
- ❌ mTLS
- ❌ Audit logging
- ❌ Secret management

## Decision

We will implement security features in the following phases:

### Phase 1: Authentication & Authorization (P0 - Critical)

**Target**: v2.0.0

1. **JWT Authentication**
   - Token-based authentication
   - Token refresh mechanism
   - Token revocation support

2. **Role-Based Access Control (RBAC)**
   - User roles (admin, user, read-only)
   - Permission system
   - Resource-level permissions

**Rationale**: No production system should run without authentication.

### Phase 2: Rate Limiting & DoS Protection (P0 - Critical)

**Target**: v2.0.0

1. **Rate Limiting**
   - Per-IP rate limiting
   - Per-user rate limiting
   - Configurable limits

2. **Request Validation**
   - Request size limits
   - Timeout configuration
   - Connection limits

**Rationale**: Prevent abuse and ensure service availability.

### Phase 3: Enhanced Logging & Monitoring (P1 - High)

**Target**: v2.1.0

1. **Audit Logging**
   - Security event logging
   - User action tracking
   - Compliance logging

2. **Security Monitoring**
   - Anomaly detection
   - Alert system
   - Security dashboards

**Rationale**: Essential for detecting and responding to security incidents.

### Phase 4: Advanced Security (P2 - Medium)

**Target**: v2.2.0

1. **Request Signing**
   - HMAC request signatures
   - Replay attack prevention
   - Timestamp validation

2. **mTLS Support**
   - Client certificate authentication
   - Certificate validation
   - Certificate rotation

**Rationale**: Enhanced security for sensitive deployments.

### Phase 5: Data Security (P2 - Medium)

**Target**: v2.3.0

1. **Encryption at Rest**
   - Database encryption
   - Field-level encryption
   - Key management

2. **Encryption in Transit**
   - TLS 1.3 enforcement
   - Strong cipher suites
   - Certificate management

**Rationale**: Protect sensitive data throughout its lifecycle.

## Implementation Details

### Phase 1: JWT Authentication

```rust
use jsonwebtoken::{encode, decode, Header, Validation, EncodingKey, DecodingKey};

#[derive(Serialize, Deserialize)]
struct Claims {
    sub: String,
    exp: usize,
    role: String,
}

// Middleware for JWT validation
async fn auth_middleware(
    State(state): State<Arc<AppState>>,
    mut req: Request<Body>,
    next: Next,
) -> Result<Response, StatusCode> {
    let token = extract_token(&req)?;
    let claims = validate_token(token)?;
    req.extensions_mut().insert(claims);
    Ok(next.run(req).await)
}
```

### Phase 2: Rate Limiting

```rust
use tower_governor::{Governor, GovernorConfigBuilder};

let governor_conf = Box::new(
    GovernorConfigBuilder::default()
        .per_second(10)
        .burst_size(20)
        .finish()
        .unwrap(),
);

let app = Router::new()
    .route("/api/v1/users", get(list_users))
    .layer(Governor::new(&governor_conf));
```

### Phase 3: Audit Logging

```rust
#[derive(Serialize)]
struct AuditLog {
    timestamp: DateTime<Utc>,
    user_id: String,
    action: String,
    resource: String,
    result: String,
    ip_address: String,
}

async fn log_audit_event(event: AuditLog) {
    // Write to audit log storage
    tracing::info!(
        target: "audit",
        user = %event.user_id,
        action = %event.action,
        "Audit event"
    );
}
```

## Security Standards

### Compliance Targets

1. **OWASP Top 10**: All items addressed
2. **CWE Top 25**: Mitigations in place
3. **NIST Cybersecurity Framework**: Aligned
4. **SOC 2**: Ready for certification (future)

### Security Testing

Each phase will include:
- Security unit tests
- Integration tests for security features
- Penetration testing
- Security code review

## Dependencies

### New Dependencies Required

Phase 1:
- `jsonwebtoken` - JWT handling
- `argon2` - Password hashing

Phase 2:
- `tower-governor` - Rate limiting
- `bb8` - Connection pooling

Phase 3:
- `sentry` - Error tracking
- `metrics` - Metrics collection

Phase 4:
- `ring` - Cryptographic operations
- `rustls` - TLS implementation

## Risks

### Implementation Risks

1. **Breaking Changes**: Authentication will be breaking change
   - Mitigation: Version properly, provide migration guide

2. **Performance Impact**: Security features may impact performance
   - Mitigation: Benchmark each phase, optimize critical paths

3. **Complexity**: More code means more potential bugs
   - Mitigation: Comprehensive testing, security reviews

### Operational Risks

1. **Secret Management**: Storing and rotating secrets
   - Mitigation: Use dedicated secret management service

2. **Certificate Management**: Dealing with certificate expiry
   - Mitigation: Automated renewal and monitoring

## Alternatives Considered

### Alternative: All Security Features at Once

**Rejected** because:
- Too complex to implement and test at once
- Higher risk of bugs
- Delays initial release
- Harder to review

### Alternative: Rely on API Gateway

**Partially Accepted**: Some features (rate limiting, auth) can be done at gateway, but:
- Defense in depth is better
- Not all deployments have API gateway
- Service-level security is good practice

## References

### Standards & Guidelines

- [OWASP API Security Top 10](https://owasp.org/www-project-api-security/)
- [NIST Cybersecurity Framework](https://www.nist.gov/cyberframework)
- [Rust Secure Code Guidelines](https://anssi-fr.github.io/rust-guide/)

### Implementation References

- [JWT Best Practices](https://tools.ietf.org/html/rfc8725)
- [OWASP Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Authentication_Cheat_Sheet.html)
- [Rate Limiting Patterns](https://cloud.google.com/architecture/rate-limiting-strategies-techniques)

## Success Criteria

Each phase complete when:
- ✅ All features implemented
- ✅ Tests pass with >80% coverage
- ✅ Security review completed
- ✅ Documentation updated
- ✅ Performance benchmarks acceptable
- ✅ Migration guide available

## Notes

This roadmap will be reviewed quarterly and adjusted based on:
- Security threat landscape
- User feedback
- Regulatory requirements
- Industry best practices

Decision made: 2025-11-22
Last updated: 2025-11-22
Review by: 2026-02-22
