Implementing a Spring Cloud Gateway with Rate Limiting, BCrypt Encryption, and JWT Authentication

The tutorial begins by outlining the objectives of mastering a microservice gateway, implementing rate limiting, using BCrypt for password encryption, and understanding JWT authentication.

1. Microservice Gateway (Spring Cloud Gateway) – explains why a gateway is needed, shows the architecture diagram, lists advantages (security, monitoring, unified authentication, reduced client calls), and compares implementations such as Nginx, Zuul, and Spring Cloud Gateway. It provides the Maven dependency, the main application class, and the application.yml configuration for routing and CORS.

2. Gateway Rate Limiting – introduces the token‑bucket algorithm, discusses burst capacity and replenish rate, and demonstrates how to configure Redis‑based rate limiting in application.yml . Code snippets for the Redis dependency and the KeyResolver bean are included.

3. BCrypt Password Encryption – shows how to generate a salt, hash a password, and verify it using the BCrypt library. Sample Java code for adding an admin user and for login verification is provided.

4. Encryption Algorithms Overview – briefly describes reversible (symmetric and asymmetric) and irreversible (hash) encryption, listing common algorithms such as AES, RSA, MD5, and SHA, and mentions Base64 encoding.

5. JWT for Microservice Authentication – explains JWT structure (header, payload, signature), shows how to create and parse tokens with the JJWT library, set expiration, and add custom claims. It also details the implementation of a JWT utility class and a gateway filter ( AuthorizeFilter ) that validates the token on each request.

Finally, the article includes testing instructions, screenshots of Postman responses, and promotional notes for related resources.