What makes JWT or session authentication safe?

Definition:

Token and session security means accepting only credentials issued by a trusted authority for the intended purpose and lifetime. A JWT can carry verifiable claims, while a server session uses stored state behind a session identifier. Both need secure transport, controlled storage, expiry and a response to credential theft.

Key points:

• Verify token signatures and claims; do not confuse decoding with validation.

• Use short-lived access tokens and a revocation strategy for sessions/refresh tokens.

• Protect transport and cookies; never write tokens into normal application logs.

• Changing a password does not automatically invalidate every existing JWT unless the system has an explicit revocation or version strategy.

Interview point:

• Separate validation, storage and revocation; choosing JWT alone does not solve any of them completely.