# A2A Registry Security Guide

## Overview

The A2A Registry implements a comprehensive, flexible security model designed to protect agent ecosystems while maintaining ease of use across development and production environments.

## Security Principles

1. **Least Privilege**: Minimal necessary access for agents and users
2. **Defense in Depth**: Multiple layers of security controls
3. **Flexible Trust Model**: Configurable security levels
4. **Transparent Security**: Clear, understandable security mechanisms

## Security Modes

### 1. Development Mode
- **Access**: Open, unrestricted
- **Purpose**: Local testing and prototyping
- **Characteristics**:
  - No authentication required
  - All agents can register
  - Minimal validation
  - Low-security environment

### 2. Production Mode
- **Access**: Strict, controlled
- **Purpose**: Secure, enterprise-grade deployments
- **Characteristics**:
  - JWT authentication mandatory
  - Role-Based Access Control (RBAC)
  - Comprehensive agent validation
  - Granular permission management

## Authentication Mechanisms

### 1. JWT (JSON Web Token) Authentication
- **Standard**: RFC 7519 compliant
- **Token Lifecycle**:
  ```python
  def generate_jwt(agent_id, roles):
      return jwt.encode({
          'sub': agent_id,
          'roles': roles,
          'exp': datetime.utcnow() + timedelta(hours=1)
      }, SECRET_KEY, algorithm='HS256')
  ```

### 2. API Key Authentication
- **Use Case**: Service-to-service communication
- **Features**:
  - Revocable keys
  - Key rotation support
  - Granular permissions

### 3. OAuth 2.0 Support
- **Providers**: Multiple identity providers
- **Grant Types**:
  - Client Credentials
  - Authorization Code
  - Device Flow

## Authorization Model

### Trust Levels
1. **Unverified**
   - Limited agent registration
   - Restricted skill access
   - Temporary credentials

2. **Verified**
   - Full agent registration
   - Expanded skill access
   - Longer-lived credentials

3. **Trusted**
   - Unlimited agent registration
   - Complete skill and extension access
   - Permanent credentials

### Role-Based Access Control (RBAC)

```python
RBAC_PERMISSIONS = {
    'AGENT_ADMIN': [
        'register_agent',
        'update_agent',
        'delete_agent',
        'manage_extensions'
    ],
    'AGENT_OPERATOR': [
        'register_agent',
        'search_agents',
        'view_agent_details'
    ],
    'AGENT_VIEWER': [
        'search_agents',
        'view_public_agent_details'
    ]
}
```

## Extension Security

### URI Allowlist Management
- Centralized extension trust configuration
- Granular URI-based controls

```python
extension_trust_config = {
    "allowed_uris": [
        "https://trusted-extensions.com/*",
        "https://verified-providers.org/*"
    ],
    "trust_levels": {
        "high": {
            "max_skills": 10,
            "requires_verification": True
        },
        "medium": {
            "max_skills": 5,
            "requires_verification": False
        }
    }
}
```

## Secure Configuration

### Environment Variables
```python
class SecuritySettings(BaseSettings):
    JWT_SECRET: str
    JWT_ALGORITHM: str = 'HS256'
    TOKEN_EXPIRATION: int = 3600  # 1 hour
    ALLOWED_ORIGINS: List[str] = []
    SECURITY_MODE: Literal['development', 'production'] = 'development'
```

## Monitoring & Incident Response

### Security Event Logging
- Comprehensive audit trails
- Tamper-evident logging
- Detailed agent activity records

### Threat Detection
- Anomaly detection
- Brute-force prevention
- Automated threat scoring

## Best Practices

1. **Authentication**
   - Use strong, randomly generated JWT secrets
   - Implement token rotation
   - Set short token expiration times

2. **Agent Registration**
   - Validate agent cards thoroughly
   - Implement multi-stage verification
   - Check protocol version compatibility

3. **Access Management**
   - Apply principle of least privilege
   - Regularly audit and rotate credentials
   - Implement fine-grained permissions

4. **Extension Security**
   - Carefully vet extension URIs
   - Limit extension capabilities
   - Implement sandboxing

## Compliance Considerations

- **GDPR**: Personal data protection
- **CCPA**: California consumer privacy
- **SOC 2**: Service organization controls
- **ISO 27001**: Information security management

## Security Roadmap

1. Enhanced machine learning-based threat detection
2. Multi-factor authentication
3. Advanced extension sandboxing
4. Comprehensive compliance reporting

## Reporting Security Issues

### Vulnerability Disclosure
- Email: security@a2a-registry.org
- PGP Key Available
- Responsible disclosure policy

## References
- [OWASP Security Guidelines](https://owasp.org/)
- [JWT RFC 7519](https://tools.ietf.org/html/rfc7519)
- [OAuth 2.0 Specification](https://oauth.net/2/)

## Disclaimer
Security is an ongoing process. Continuously update and review your security configurations.