A comprehensive tutorial on Spring Security demonstrates how to extend JWT authentication with refresh tokens to balance security and usability. The guide begins by explaining the limitations of short-lived access tokens, which typically expire within 15 minutes to one hour, and introduces refresh tokens that can last from one week to one month.
The article details the creation of a RefreshToken entity annotated with JPA mappings, including fields for the token string, associated user, expiration instant, and revocation flag. It also provides the corresponding RefreshTokenRepository interface with methods to find tokens and delete all tokens for a given user.
In the service layer, RefreshTokenService implements token creation by removing existing tokens for the user, generating a new UUID-based token, setting an expiration based on a configurable property, and persisting it. The verify method checks for existence, expiration, and revocation status, throwing a custom RefreshTokenException when necessary, while the revoke method marks tokens as revoked.
Security considerations are thoroughly covered, highlighting benefits such as reduced exposure time for access tokens, automatic session renewal, centralized session control, and minimized password transmission. Risks discussed include potential database compromise mitigated by hashing with SHA-256 or HMAC-SHA256, increased database load due to statefulness, implementation complexity involving token rotation, and client-side storage vulnerabilities addressed by using HttpOnly cookies instead of localStorage.
The tutorial updates DTOs to include AuthResponse and RefreshRequest, modifies AuthService to integrate refresh token creation during registration and login, and enhances AuthController with endpoints for refresh and logout. A helper method sets secure, HTTP-only cookies with appropriate path and max-age settings.
Finally, adjustments to SecurityConfig are shown to permit public access to authentication endpoints and profile retrieval while restricting administrative routes, ensuring a complete implementation of refresh token mechanics alongside JWT handling.
