JWT and OAuth 2.0: When Each Approach Makes Sense
Stateless tokens vs. server-side sessions, RS256 asymmetric signing, refresh token rotation, and architecting secure authentication for web and mobile.
Authentication is the security perimeter of any modern application. Yet confusion persists regarding when to use stateless JSON Web Tokens (JWTs), stateful session cookies, or full OAuth 2.0 / OpenID Connect delegation.
1. Stateless JWTs: Benefits and Gotchas
JWTs allow microservices and distributed backend nodes to verify claims without hitting a central database on every HTTP request. However, because JWTs are self-contained, immediate token revocation is difficult unless paired with a short lifespan (10-15 minutes) and a Redis-backed refresh token blocklist.
2. Asymmetric Signing: RS256 over HS256
For production microservice architectures, asymmetric cryptography (RS256/EdDSA) is preferred over symmetric keys (HS256). The authorization server holds the private key to sign tokens, while resource servers verify tokens using the public key alone without risking secret leaks.
3. Secure Storage: Web vs. Mobile
Never store JWT access tokens in browser localStorage where they are vulnerable to Cross-Site Scripting (XSS). In web applications, store tokens in httpOnly, SameSite=Strict secure cookies. On mobile platforms (Android/iOS), store secrets in the hardware Keystore / Keychain.
Practical Engineering Takeaways
- ✓Use short-lived access tokens (10-15m) with rotating refresh tokens.
- ✓Sign tokens using RS256 asymmetric keys in distributed systems.
- ✓Protect web tokens in httpOnly, SameSite cookies to mitigate XSS extraction.
- ✓Use native Keystore/Keychain on mobile devices.
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