Enterprise-Grade Authentication & Authorization System

Build a secure, user-friendly authentication system that supports: • Multiple authentication methods (credentials + OAuth providers) • Fine-grained authorization with role-based access control • Secure session management across devices • Protection against common attacks (brute force, session hijacking, CSRF) • Seamless user experience (SSO, remember me, password reset) • Compliance with security best practices (OWASP Top 10) The system needed to be flexible enough to add new OAuth providers and permission schemes as the platform evolved.

Implemented a modular authentication architecture using NestJS Guards, Passport.js strategies, and JWT tokens: • Multi-Strategy Authentication: Passport.js with local, Google, and GitHub strategies • Secure Token Management: Short-lived access tokens (15min) + long-lived refresh tokens (7 days) with rotation • Role-Based Access Control: Hierarchical permission system (Admin > Instructor > Student) • Security Layers: bcrypt password hashing, rate limiting, CSRF protection, httpOnly cookies • Audit Trail: Complete logging of authentication events for security monitoring • Developer Experience: Decorators for clean authorization (@Roles, @Public, @CurrentUser)