Security Patterns in Modern Architectures
Token-based authentication and authorization are foundational to building scalable and secure distributed systems. In the era of SPAs and Microservices, the traditional cookie-based session is often replaced or augmented by stateless mechanisms like JWTs.
Authentication vs. Authorization
It is vital to distinguish these two concepts:
- Authentication (AuthN): "Who are you?" This is the process of verifying identity via passwords, biometrics, or magic links.
- Authorization (AuthZ): "What can you do?" Once identity is established, this determines permission levels (e.g., Admin vs User).
1. Securing SPAs and Mobile Apps
Traditional session-based authentication doesn't work well with Single-Page Applications (React, Vue) and mobile apps due to Cross-Origin Resource Sharing (CORS) issues. JWTs (JSON Web Tokens) provide a stateless solution: the server doesn't need to store session data in memory or a database. Each request from the client is self-contained and authenticated by its token.
2. Microservices Architecture
In a microservices architecture, you can have a dedicated "Auth Service" that handles user logins and issues JWTs. Other services (e.g., "Product Service", "Order Service") can then independently verify the signature of these JWTs using a shared secret or public key to authenticate requests without needing to communicate with the Auth Service for every single call.
3. Fine-Grained Permissions with OAuth 2.0
OAuth goes beyond simple roles. When an application asks for permission to access your Google account, it requests specific "scopes" like `read:calendar` or `write:contacts`. This is a form of fine-grained authorization where the user grants specific, limited permissions.
Security Tip: Never store sensitive secrets (like passwords) in plain text. Always hash passwords with a strong algorithm like bcrypt. Never store sensitive data inside a JWT payload, as it can be easily decoded by anyone.