https://sohilladhani.com/blog/tags/authentication/Recent content in Authentication on Sohil Ladhani BlogHugoen-usSun, 19 Apr 2026 00:00:00 +0000https://sohilladhani.com/blog/post/2026-04-19-token-revocation-and-blacklisting/Sun, 19 Apr 2026 00:00:00 +0000https://sohilladhani.com/blog/post/2026-04-19-token-revocation-and-blacklisting/You log out. Your JWT is still valid. The server has no record it was ever issued. This is the stateless token revocation problem. Why Revocation Is Hard JWTs are stateless by design. The server validates a token by checking the signature and expiry. It doesn’t consult a database. This is what makes them fast and scalable. But it means there’s no central list of “valid tokens” to update when a token should no longer be accepted.https://sohilladhani.com/blog/post/2026-04-18-oauth2-authorization-flows/Sat, 18 Apr 2026 00:00:00 +0000https://sohilladhani.com/blog/post/2026-04-18-oauth2-authorization-flows/OAuth 2.0 is not an authentication protocol. It’s an authorization protocol. That confusion is the root of most OAuth misuse. What OAuth Actually Does OAuth lets a user grant a third-party application limited access to their account without sharing their password. The user sees a consent screen listing what the app wants to access. They approve. The app gets a token with exactly those permissions. Your password never leaves the authorization server.https://sohilladhani.com/blog/post/2026-04-17-jwt-token-based-auth/Fri, 17 Apr 2026 00:00:00 +0000https://sohilladhani.com/blog/post/2026-04-17-jwt-token-based-auth/The server doesn’t remember you. Every request carries proof of who you are. That’s the point of a token. The Structure A JWT is three base64url-encoded segments joined by dots: header, payload, signature. The header says which algorithm signed it. The payload carries claims: user ID, roles, expiry time. The signature is a cryptographic proof that the header and payload haven’t been tampered with. The server doesn’t need a database lookup to verify a JWT.