# ADR-010: HIPAA Compliance Strategy

## Status
Accepted

## Context
MediGuard AI processes Protected Health Information (PHI) and must comply with HIPAA (Health Insurance Portability and Accountability Act) requirements. Key compliance needs include:
- Data encryption at rest and in transit
- Access controls and audit logging
- Data minimization and retention policies
- Business Associate Agreement (BAA) with cloud providers
- Secure development practices

## Decision
Implement a comprehensive HIPAA compliance strategy:

### 1. Data Protection
- **Encryption**: AES-256 encryption for data at rest, TLS 1.3 for data in transit
- **Key Management**: Use AWS KMS or similar for key rotation
- **Data Masking**: Mask PHI in logs and monitoring
- **Minimal Data Storage**: Only store necessary PHI with automatic deletion

### 2. Access Controls
- **Authentication**: Multi-factor authentication for admin access
- **Authorization**: Role-based access control (RBAC)
- **Audit Logging**: Comprehensive audit trail for all data access
- **Session Management**: Secure session handling with timeouts

### 3. Infrastructure Security
- **Network Security**: VPC with private subnets, security groups
- **Container Security**: Non-root containers, security scanning
- **Secrets Management**: AWS Secrets Manager or HashiCorp Vault
- **Backup Security**: Encrypted backups with secure retention

### 4. Development Practices
- **Code Review**: Security-focused code reviews
- **Static Analysis**: Automated security scanning (Bandit, Semgrep)
- **Dependency Scanning**: Regular vulnerability scans
- **Penetration Testing**: Annual security assessments

## Consequences

### Positive
- **Compliance**: Meets HIPAA requirements for healthcare data
- **Trust**: Builds trust with healthcare providers and patients
- **Security**: Robust security posture beyond HIPAA minimums
- **Market**: Enables entry into healthcare market
- **Risk**: Reduced risk of data breaches and penalties

### Negative
- **Complexity**: Additional security measures increase complexity
- **Cost**: Higher infrastructure and compliance costs
- **Performance**: Security measures may impact performance
- **Development**: Slower development due to security requirements

## Implementation

### Encryption Example
```python
class PHIEncryption:
    def __init__(self, key_manager):
        self.key_manager = key_manager
        
    def encrypt_phi(self, data: str) -> str:
        key = self.key_manager.get_latest_key()
        return AES.encrypt(data, key)
        
    def decrypt_phi(self, encrypted_data: str) -> str:
        key_id = extract_key_id(encrypted_data)
        key = self.key_manager.get_key(key_id)
        return AES.decrypt(encrypted_data, key)
```

### Audit Logging
```python
class HIPAAAuditMiddleware:
    async def log_access(self, user_id: str, resource: str, action: str):
        audit_entry = {
            "timestamp": datetime.utcnow(),
            "user_id": self.hash_user_id(user_id),
            "resource": resource,
            "action": action,
            "ip_address": self.get_client_ip()
        }
        await self.audit_logger.log(audit_entry)
```

### Data Minimization
```python
class DataRetentionPolicy:
    def __init__(self):
        self.retention_periods = {
            "analysis_results": timedelta(days=365),
            "user_sessions": timedelta(days=30),
            "audit_logs": timedelta(days=2555)  # 7 years
        }
    
    async def cleanup_expired_data(self):
        for data_type, retention in self.retention_periods.items():
            cutoff = datetime.utcnow() - retention
            await self.delete_data_before(data_type, cutoff)
```

## Notes
- All cloud providers must sign BAAs
- Regular compliance audits (at least annually)
- Incident response plan for data breaches
- Employee training on HIPAA requirements
- Business continuity planning for disaster recovery
- Legal review of all compliance measures