auth2/docs/PROJECT_PLAN.md

Auth2 Library Implementation Plan

This document outlines the step-by-step implementation plan for the Auth2 library, a comprehensive, production-ready authentication solution for Go applications.

Phase 1: Foundation & Core Architecture

1.1 Project Setup

• Initialize Go module and directory structure
• Set up logging with log/slog
• Create error types and handling mechanisms
• Implement configuration structures

1.2 Plugin System Architecture

• Design provider interfaces for each plugin type
• Implement provider registry for managing registered plugins
• Create provider metadata system for version and capability information
• Implement factory pattern for provider instantiation
• Build provider discovery mechanism

1.3 Core Domain Models

• Define User model and interfaces
• Create Context wrapper for auth context
• Implement base interfaces for all components
• Build error handling patterns

Phase 2: Core Authentication Framework

2.1 Authentication Provider Interface

• Define AuthProvider interface
• Create ProviderManager for managing multiple providers
• Implement provider registration system
• Build chain-of-responsibility pattern for auth attempts

2.2 Basic Authentication

• Implement username/password provider
• Create password hashing utilities (bcrypt, argon2id)
• Build password policy enforcement
• Implement account locking mechanism

2.3 WebAuthn/FIDO2 as Primary Authentication

• Implement WebAuthn passwordless registration
• Create WebAuthn passwordless authentication
• Build attestation verification
• Implement credential storage and management
• Create dual-mode provider interface for both primary and MFA use

2.4 OAuth2 Framework

• Design generic OAuth2 provider
• Implement OAuth2 flow handlers
• Create token storage and validation
• Build user profile mapping utilities

2.5 OAuth2 Providers

• Implement Google OAuth2 provider
• Implement GitHub OAuth2 provider
• Implement Microsoft OAuth2 provider
• Implement Facebook OAuth2 provider

2.6 SAML Authentication

• Implement SAML provider interface
• Create SAML assertion parser
• Build SAML request/response handlers
• Implement metadata handlers

Phase 3: Multi-Factor Authentication

3.1 MFA Framework

• Define MFA provider interface
• Create MFA registration flow
• Implement MFA verification flow
• Build MFA fallback mechanisms

3.2 TOTP Implementation

• Implement TOTP algorithm (RFC 6238)
• Create QR code generation for setup
• Build key storage and management
• Implement validation with drift windows

3.3 WebAuthn/FIDO2 as MFA

• Implement WebAuthn MFA registration
• Create WebAuthn MFA verification
• Build integration with primary authentication methods
• Implement fallback mechanisms

3.4 Email OTP

• Create email OTP generation
• Implement OTP storage and validation
• Build email delivery interface
• Create rate limiting for OTP requests

3.5 Backup Codes

• Implement secure backup code generation
• Create storage and validation
• Build code regeneration mechanism
• Implement usage tracking

Phase 4: Session Management

4.1 Session Framework

• Define Session interface
• Create SessionManager interface
• Implement session creation/validation flow
• Build session store interface

4.2 Cookie Sessions

• Implement secure cookie creation
• Create cookie signing and encryption
• Build cookie session validation
• Implement cookie refresh mechanism

4.3 JWT Sessions

• Implement JWT generation and validation
• Create claims mapping system
• Build key rotation mechanism
• Implement token blacklisting for revocation

4.4 Bearer Token Management

• Create token generation and validation
• Implement token refresh mechanism
• Build token revocation system
• Create token metadata storage

Phase 5: RBAC Implementation

5.1 RBAC Core

• Define Role and Permission models
• Create RBACManager interface
• Implement permission checking
• Build role assignment mechanisms

5.2 Permission Management

• Implement permission creation and management
• Create permission inheritance system
• Build permission checking optimization
• Implement permission caching

5.3 Role Management

• Create role hierarchy system
• Implement role assignment to users
• Build role relationship management
• Create role-based permission resolution

5.4 Group Management

• Implement group creation and management
• Create user group assignment
• Build group-role relationships
• Implement group-based permission resolution

Phase 6: Storage Adapters

6.1 Storage Interface

• Define comprehensive storage interfaces
• Create adapter registration system
• Implement transaction support
• Build query interface

6.2 In-Memory Storage

• Implement in-memory user storage
• Create in-memory session storage
• Build in-memory RBAC storage
• Implement test utilities

6.3 SQL Adapter

• Create standard SQL implementation
• Implement SQL schema management
• Build query optimization
• Create connection pooling

6.4 GORM Adapter

• Implement GORM models
• Create GORM repository implementations
• Build efficient query patterns
• Implement migration utilities

6.5 Ent Adapter

• Create Ent schema definitions
• Implement Ent client wrappers
• Build repository implementations
• Create efficient query builders

Phase 7: HTTP Framework Integration

7.1 HTTP Framework Interface

• Define middleware interface
• Create request parser interface
• Implement response writer interface
• Build route registration system

7.2 Standard Library Integration

• Implement net/http middleware
• Create request handlers
• Build response utilities
• Implement session management

7.3 Framework-Specific Adapters

• Implement Chi integration
• Create Echo integration
• Build Fiber integration
• Implement Gin integration
• Create Gorilla Mux integration
• Build httprouter integration
• Implement Huma integration
• Create FastHTTP integration

Phase 8: Security Features

8.1 Rate Limiting

• Implement rate limiter interface
• Create in-memory rate limiter
• Build distributed rate limiter
• Implement rate limit middleware

8.2 Brute Force Protection

• Create failed attempt tracking
• Implement progressive backoff
• Build account locking mechanism
• Create notification system

8.3 CSRF Protection

• Implement token generation and validation
• Create CSRF middleware
• Build token storage
• Implement SameSite cookie protection

8.4 Password Security

• Create password strength validation
• Implement password history
• Build password rotation policies
• Create secure password reset flow

8.5 Account Recovery

• Implement secure recovery flow
• Create recovery token management
• Build multi-channel verification
• Implement account recovery audit

Phase 9: User Management

9.1 Registration Flow

• Implement user registration
• Create email verification
• Build user activation flow
• Implement profile creation

9.2 Profile Management

• Create profile update functionality
• Implement data validation
• Build custom field support
• Create profile data encryption

9.3 Account Management

• Implement account locking/unlocking
• Create password reset flow
• Build account deletion
• Implement account merging

Phase 10: Testing & Documentation

10.1 Unit Testing

• Create comprehensive test suite for core components
• Implement mock providers
• Build test utilities
• Create test coverage reports

10.2 Integration Testing

• Implement end-to-end authentication flow tests
• Create storage adapter tests
• Build HTTP integration tests
• Implement security feature tests

10.3 Documentation

• Create comprehensive API documentation
• Build usage examples
• Implement godoc-compatible documentation
• Create security best practices guide

10.4 Example Applications

• Build basic authentication example
• Create complete feature showcase
• Implement custom provider example
• Build framework integration examples

Deliverables Timeline

Milestone 1: Core Framework (Weeks 1-2)

• Project setup complete
• Plugin system architecture implemented
• Core domain models defined
• Basic authentication working

Milestone 2: Authentication Providers (Weeks 3-4)

• OAuth2 framework implemented
• All OAuth2 providers working
• SAML authentication working
• WebAuthn passwordless authentication working
• Session management framework complete

Milestone 3: MFA & Security (Weeks 5-6)

• All MFA methods implemented
• Security features working
• RBAC implementation complete
• User management flows working

Milestone 4: Storage & HTTP Integration (Weeks 7-8)

• All storage adapters implemented
• HTTP framework integration complete
• Integration tests passing
• Documentation complete

Quality Assurance Approach

Code Quality

• All code must pass linting and formatting checks
• Test coverage must exceed 80%
• No exported function, type, or variable without documentation
• No known security vulnerabilities