Validating JWTs: Signature, Expiry, and Claims
The full JWT validation checklist: algorithm, signature, expiry, issuer, audience, and claims — in the right order.
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Tags: security, jwt, validation
Validating JWT Tokens: Signature, Expiry, and Claims Check Decoding a JWT shows you the claims. Validating a JWT proves those claims are trustworthy. The two operations are completely different, and confusing them is one of the most common JWT security mistakes. A full JWT validation checks five things, in this order: signature, algorithm, expiry, not-before, and then application-specific claims like issuer and audience. Why Order Matters Validation should be ordered from cheapest-to-compute to most-expensive, and from most-critical to least-critical. Signature verification is computationally expensive (especially for RSA) but must come first — if the signature is invalid, nothing else matters. The claims are untrustworthy and should be discarded immediately without reading. Expiry check…
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