Security Architecture
===================

This document outlines the security architecture of the AI-Writer platform, including authentication, authorization, data protection, and security best practices.

Authentication and Authorization
------------------------------

User Authentication
~~~~~~~~~~~~~~~~~

AI-Writer implements a multi-layered authentication system:

1. **Password-based Authentication**
   
   * Passwords are hashed using bcrypt with appropriate work factors
   * Password complexity requirements are enforced
   * Account lockout after multiple failed attempts
   * Password reset via secure email workflow

2. **API Key Authentication**
   
   * Unique API keys for programmatic access
   * Keys are stored using secure hashing
   * Keys can be scoped to specific permissions
   * Keys can be revoked at any time

3. **OAuth 2.0 (for multi-user deployments)**
   
   * Standard OAuth 2.0 flow with authorization code
   * JWT tokens with appropriate expiration
   * Refresh token rotation
   * PKCE for public clients

Authorization Model
~~~~~~~~~~~~~~~~

The platform uses a role-based access control (RBAC) system:

1. **User Roles**
   
   * **Admin**: Full system access
   * **Editor**: Content creation and editing
   * **Viewer**: Read-only access to content
   * **API**: Programmatic access with limited scope

2. **Permission Scopes**
   
   * `content:read`: View content
   * `content:write`: Create and edit content
   * `content:delete`: Delete content
   * `user:read`: View user information
   * `user:write`: Modify user information
   * `settings:read`: View settings
   * `settings:write`: Modify settings
   * `api:manage`: Manage API keys

3. **Resource-level Permissions**
   
   * Permissions are checked at the resource level
   * Users can only access their own content
   * Sharing functionality with explicit permissions

Data Protection
-------------

Encryption
~~~~~~~~~

1. **Data in Transit**
   
   * TLS 1.3 for all communications
   * Strong cipher suites
   * HSTS implementation
   * Certificate pinning for API clients

2. **Data at Rest**
   
   * Database encryption
   * Encrypted file storage
   * Secure key management
   * Regular key rotation

3. **Sensitive Data**
   
   * API keys and credentials are encrypted
   * PII is encrypted with separate keys
   * Encryption keys are properly secured

API Key Security
~~~~~~~~~~~~~~

1. **Key Generation**
   
   * Keys are generated using cryptographically secure random functions
   * Sufficient entropy (256 bits)
   * Keys follow a consistent format for validation

2. **Key Storage**
   
   * Only key hashes are stored in the database
   * Secure comparison for validation
   * Keys are never logged or exposed in error messages

3. **Key Management**
   
   * Keys can be rotated regularly
   * Unused keys are automatically expired
   * Key usage is logged for audit purposes

Secure Development Practices
--------------------------

Input Validation
~~~~~~~~~~~~~~

1. **API Input Validation**
   
   * All input is validated against schemas
   * Type checking and constraint validation
   * Protection against injection attacks
   * Input sanitization where appropriate

2. **Content Validation**
   
   * Content is scanned for malicious elements
   * HTML/Markdown sanitization
   * File upload validation and scanning

3. **Error Handling**
   
   * Secure error handling that doesn't leak sensitive information
   * Consistent error responses
   * Detailed internal logging for troubleshooting

Dependency Management
~~~~~~~~~~~~~~~~~~

1. **Dependency Scanning**
   
   * Regular scanning for vulnerable dependencies
   * Automated updates for security patches
   * Dependency pinning for stability

2. **Minimal Dependencies**
   
   * Only necessary dependencies are included
   * Regular dependency audits
   * Preference for well-maintained libraries

3. **Containerization**
   
   * Minimal base images
   * Non-root container execution
   * Image scanning for vulnerabilities

Logging and Monitoring
--------------------

Security Logging
~~~~~~~~~~~~~~

1. **Authentication Events**
   
   * Login attempts (successful and failed)
   * Password changes and resets
   * API key creation and usage
   * Session management events

2. **Authorization Events**
   
   * Permission checks
   * Access denials
   * Privilege escalation
   * Role changes

3. **System Events**
   
   * Configuration changes
   * Service starts and stops
   * Database migrations
   * Backup and restore operations

Monitoring and Alerting
~~~~~~~~~~~~~~~~~~~~~

1. **Security Monitoring**
   
   * Real-time monitoring for suspicious activities
   * Anomaly detection for unusual patterns
   * Rate limiting and abuse detection
   * Geographic anomaly detection

2. **Performance Monitoring**
   
   * Resource usage tracking
   * API response time monitoring
   * Error rate monitoring
   * Database performance tracking

3. **Alerting**
   
   * Immediate alerts for security incidents
   * Escalation procedures
   * On-call rotation
   * Incident response playbooks

Compliance and Privacy
--------------------

Data Governance
~~~~~~~~~~~~~

1. **Data Classification**
   
   * Clear classification of data sensitivity
   * Handling procedures for each classification
   * Access controls based on classification
   * Retention policies by data type

2. **Data Minimization**
   
   * Only necessary data is collected
   * Automatic data pruning
   * Anonymization where possible
   * Purpose limitation

3. **User Consent**
   
   * Clear consent mechanisms
   * Granular permission options
   * Easy consent withdrawal
   * Consent records

Privacy Features
~~~~~~~~~~~~~

1. **User Privacy Controls**
   
   * Data export functionality
   * Account deletion
   * Privacy settings management
   * Usage tracking opt-out

2. **Data Portability**
   
   * Export in standard formats
   * Complete data export
   * Machine-readable formats
   * Import capabilities

3. **Transparency**
   
   * Clear privacy policy
   * Data usage explanations
   * Third-party data sharing disclosure
   * Processing activities documentation

Security Testing
--------------

Vulnerability Management
~~~~~~~~~~~~~~~~~~~~~

1. **Security Testing**
   
   * Regular penetration testing
   * Static application security testing (SAST)
   * Dynamic application security testing (DAST)
   * Software composition analysis (SCA)

2. **Bug Bounty Program**
   
   * Responsible disclosure policy
   * Security researcher engagement
   * Vulnerability triage process
   * Remediation tracking

3. **Security Reviews**
   
   * Code reviews with security focus
   * Architecture security reviews
   * Threat modeling
   * Security design reviews

Incident Response
~~~~~~~~~~~~~~~

1. **Incident Response Plan**
   
   * Defined incident response procedures
   * Roles and responsibilities
   * Communication templates
   * Escalation paths

2. **Breach Notification**
   
   * Legal compliance with notification requirements
   * User communication plan
   * Regulatory reporting procedures
   * Post-incident analysis

3. **Recovery Procedures**
   
   * Backup and restore testing
   * Business continuity planning
   * Disaster recovery procedures
   * Service level objectives

Security Roadmap
--------------

Planned Security Enhancements
~~~~~~~~~~~~~~~~~~~~~~~~~~~

1. **Short-term (0-6 months)**
   
   * Implement multi-factor authentication
   * Enhance API key management
   * Improve security logging
   * Conduct initial penetration test

2. **Medium-term (6-12 months)**
   
   * Implement security information and event management (SIEM)
   * Enhance data encryption
   * Develop comprehensive security training
   * Implement automated security testing in CI/CD

3. **Long-term (12+ months)**
   
   * Achieve SOC 2 compliance
   * Implement advanced threat protection
   * Develop zero-trust architecture
   * Enhance privacy features for international compliance