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ADR-0005: Authentication and Authorization Strategy

Status

PROPOSED

Date: 2025-07-05

Changelog

Date Revision Description Author
2025-07-05 1.0 Initial version souperk

Context

As Loryth grows into a multiservice system with various user roles and permissions, we need a robust authentication and authorization strategy. This strategy must:

  • Provide secure user identity verification
  • Support role-based access control across services
  • Enable fine-grained permission management
  • Be consistent across all services
  • Support multifactor authentication for enhanced security
  • Scale with our growing user base
  • Protect against common security threats

Without a comprehensive strategy, we risk inconsistent security implementations, potential vulnerabilities, and maintenance challenges as the system grows.

Decision

We will implement a centralized authentication and authorization system with the following components:

  1. Identity and Access Management Service:

    • Dedicated IAM service to manage user identity and authentication
    • Support for username/password and OAuth2 identity providers
    • Multifactor authentication capability
    • User profile and role management

  2. Token-Based Authentication:

    • JWT (JSON Web Tokens) for representing authenticated sessions
    • Short-lived access tokens (15-60 minutes)
    • Longer-lived refresh tokens with secure storage
    • Token rotation and revocation mechanisms

  3. Authorization Model:

    • Role-Based Access Control (RBAC) as the primary authorization model
    • Support for Attribute-Based Access Control (ABAC) for complex permissions
    • Permission inheritance through role hierarchies
    • Resource-based permissions for fine-grained control

  4. Service-to-Service Authentication:

    • Service-specific credentials and tokens
    • Mutual TLS for secure service-to-service communication
    • Limited-scope service accounts with the principle of the least privilege

  5. Implementation Approach:

    • Authentication enforcement at the API gateway level
    • Authorization checks at service boundaries
    • Common library for consistent token validation and authorization checks
    • Security context propagation through service calls

  6. Security Enhancements:

    • Rate limiting to prevent brute force attacks
    • Audit logging for all authentication and authorization events
    • Regular security scanning and penetration testing
    • Token binding to prevent token theft

Consequences

Positive

  • Consistent security: Uniform security implementation across all services
  • Centralized management: Single point for user and role management
  • Enhanced security: Support for advanced security features like MFA
  • Scalability: Architecture designed to scale with user growth
  • Flexibility: Support for multiple authentication methods and providers
  • Auditability: Comprehensive logging of security events

Negative

  • Additional complexity: More complex system architecture with dedicated IAM service
  • Potential single point of failure: IAM service availability affects all authentication
  • Performance overhead: Token validation adds latency to requests
  • Development overhead: Developers need to implement consistent security checks

Neutral

  • Token size considerations: Need to balance token information content with size
  • Cache considerations: Token validation caching needed for performance
  • Implementation effort: Significant initial implementation effort but long-term benefits

Alternatives Considered

  1. Service-specific authentication

    • Description: Each service implements its own authentication and authorization
    • Pros:
      • Services have complete control over their security
      • No dependencies on a central authentication service
    • Cons:
      • Inconsistent security implementations
      • Duplicated user data across services
      • No single sign-on capability
      • Difficult to manage roles across services
    • Why not chosen: Would lead to fragmented security and poor user experience

  2. Third-party identity provider only

    • Description: Rely entirely on external providers (Google, GitHub, etc.)
    • Pros:
      • Reduced implementation complexity
      • Leverages established security providers
      • No password management responsibility
    • Cons:
      • Dependency on external providers
      • Limited control over an authentication process
      • Potential integration challenges for custom requirements
    • Why not chosen: Insufficient control and flexibility for our specific needs

  3. Session-based authentication

    • Description: Traditional server-side sessions instead of tokens
    • Pros:
      • Familiar pattern for developers
      • Direct server control over sessions
      • Simpler revocation
    • Cons:
      • Scaling challenges with distributed architecture
      • Session state management complexity
      • Not ideal for service-to-service communication
    • Why not chosen: Not well-suited for our distributed architecture

References