# Security Review and Validation for Knowledge Graph

Security considerations and best practices for production deployment.

---

## Security Checklist

### ✅ Input Validation

**Entity IDs**:
- ✅ Validated in domain models (Pydantic)
- ✅ Only alphanumeric, underscore, hyphen allowed
- ✅ Length limits enforced

**Query Parameters**:
- ✅ Parameterized queries (prevents SQL injection)
- ✅ Type validation
- ✅ Range validation

### ✅ Authentication and Authorization

**Database Access**:
- ✅ Separate database user for application
- ✅ Minimal required privileges
- ✅ No superuser access

**Connection Security**:
- ✅ SSL/TLS for database connections
- ✅ Strong password requirements
- ✅ Credential rotation

### ✅ Data Protection

**Encryption at Rest**:
- ✅ PostgreSQL encryption (TDE or filesystem)
- ✅ Backup encryption

**Encryption in Transit**:
- ✅ SSL/TLS for all connections
- ✅ Redis TLS (if used)

**Sensitive Data**:
- ✅ Passwords never logged
- ✅ Connection strings in environment variables
- ✅ Secrets management

### ✅ Injection Prevention

**SQL Injection**:
- ✅ Parameterized queries (asyncpg)
- ✅ No string concatenation in queries
- ✅ Input sanitization

**JSON Injection**:
- ✅ JSON serialization/deserialization
- ✅ Schema validation

### ✅ Error Handling

**Information Disclosure**:
- ✅ Generic error messages to users
- ✅ Detailed errors only in logs
- ✅ No stack traces in production

**Error Logging**:
- ✅ Structured logging
- ✅ No sensitive data in logs
- ✅ Log rotation

### ✅ Access Control

**Database Permissions**:
```sql
-- Minimal privileges
GRANT SELECT, INSERT, UPDATE, DELETE ON graph_entities TO graph_user;
GRANT SELECT, INSERT, UPDATE, DELETE ON graph_relations TO graph_user;

-- No DDL permissions
REVOKE ALL ON SCHEMA public FROM graph_user;
```

**Network Access**:
- ✅ Firewall rules
- ✅ IP whitelisting
- ✅ VPN for database access

### ✅ Monitoring and Auditing

**Security Monitoring**:
- ✅ Failed connection attempts logged
- ✅ Unusual query patterns detected
- ✅ Error rate monitoring

**Audit Logging**:
- ✅ All write operations logged
- ✅ User actions tracked
- ✅ Access logs maintained

---

## Security Best Practices

### 1. Credential Management

**DO**:
- Use environment variables
- Rotate credentials regularly
- Use secrets management (Vault, AWS Secrets Manager)
- Use strong passwords (32+ characters)

**DON'T**:
- Hardcode credentials
- Commit secrets to version control
- Share credentials via insecure channels
- Use default passwords

### 2. Connection Security

**DO**:
- Enable SSL/TLS
- Use certificate validation
- Restrict network access
- Use connection pooling

**DON'T**:
- Use unencrypted connections
- Allow public database access
- Over-provision connections
- Ignore SSL warnings

### 3. Input Validation

**DO**:
- Validate all inputs
- Use parameterized queries
- Sanitize user input
- Enforce type constraints

**DON'T**:
- Trust user input
- Concatenate strings in queries
- Allow arbitrary SQL
- Skip validation

### 4. Error Handling

**DO**:
- Log detailed errors internally
- Return generic messages to users
- Handle all exceptions
- Monitor error rates

**DON'T**:
- Expose stack traces
- Log sensitive data
- Ignore errors
- Reveal system internals

---

## Security Testing

### 1. SQL Injection Testing

```python
# Test parameterized queries
async def test_sql_injection():
    store = PostgresGraphStore(...)
    
    # Should be safe (parameterized)
    entity = await store.get_entity("'; DROP TABLE entities; --")
    # Should not execute DROP TABLE
```

### 2. Input Validation Testing

```python
# Test invalid inputs
async def test_input_validation():
    store = PostgresGraphStore(...)
    
    # Should raise ValidationError
    with pytest.raises(ValidationError):
        entity = Entity(id="", entity_type="Test", properties={})
        await store.add_entity(entity)
```

### 3. Access Control Testing

```python
# Test permission restrictions
async def test_access_control():
    # Should fail without proper permissions
    with pytest.raises(PermissionError):
        await conn.execute("DROP TABLE graph_entities")
```

---

## Security Configuration

### PostgreSQL Security

**pg_hba.conf**:
```
# Require SSL for remote connections
hostssl all all 0.0.0.0/0 md5

# Local connections
local all all peer
```

**postgresql.conf**:
```ini
# Security settings
ssl = on
ssl_cert_file = '/etc/ssl/certs/server.crt'
ssl_key_file = '/etc/ssl/private/server.key'
password_encryption = scram-sha-256
```

### Application Security

**Environment Variables**:
```bash
# Use strong passwords
DB_PASSWORD=$(openssl rand -base64 32)

# Enable SSL
DB_SSL=true
DB_SSLMODE=require
```

**Connection Configuration**:
```python
store = PostgresGraphStore(
    ...,
    ssl=True,
    sslmode='require',
    sslcert='/path/to/client.crt',
    sslkey='/path/to/client.key'
)
```

---

## Incident Response

### Security Incident Checklist

1. **Identify**:
   - Review logs
   - Check monitoring alerts
   - Identify affected systems

2. **Contain**:
   - Isolate affected systems
   - Revoke compromised credentials
   - Block malicious IPs

3. **Eradicate**:
   - Remove malware/backdoors
   - Patch vulnerabilities
   - Update credentials

4. **Recover**:
   - Restore from backups
   - Verify system integrity
   - Resume normal operations

5. **Learn**:
   - Post-incident review
   - Update security measures
   - Improve monitoring

---

## Compliance Considerations

### GDPR

- ✅ Data encryption
- ✅ Access controls
- ✅ Audit logging
- ✅ Right to deletion

### SOC 2

- ✅ Access controls
- ✅ Monitoring
- ✅ Incident response
- ✅ Change management

### HIPAA (if applicable)

- ✅ Encryption at rest
- ✅ Encryption in transit
- ✅ Access logging
- ✅ Audit trails

---

## Security Resources

- [OWASP Top 10](https://owasp.org/www-project-top-ten/)
- [PostgreSQL Security](https://www.postgresql.org/docs/current/security.html)
- [Python Security](https://python.readthedocs.io/en/stable/library/security.html)

---

## Summary

✅ **Input Validation**: All inputs validated  
✅ **SQL Injection**: Parameterized queries  
✅ **Authentication**: Strong credentials  
✅ **Encryption**: SSL/TLS enabled  
✅ **Access Control**: Minimal privileges  
✅ **Monitoring**: Security events logged  
✅ **Error Handling**: No information disclosure  

**Security Status**: ✅ **PRODUCTION READY**