hard20 pts · first answer countsjwtsecurity

JWT verified with an attacker-chosen algorithm

Your API verifies RS256 tokens using the public key, but its verify call accepts whatever algorithm the token header says. An attacker sends a token with alg HS256, signed with your public key as the HMAC secret. How do you stop this?

A.Pin the allowed algorithm when verifying, for example algorithms: ['RS256'], and never let the token header choose itB.Keep the public key secret and share it only with services that verify tokens, so attackers cannot sign with itC.Shorten the token lifetime to five minutesD.Encode the token in base64 twice

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