JWT validation ensures the token has not been tampered with, a critical step in secure authentication. Tokens that fail validation may have been maliciously modified and should not be trusted.
Symmetric algorithms like HS256 use the same key for signing and verification. The key must exactly match the one used at generation for successful validation.
Asymmetric algorithms like RS256 use a private key for signing and a public key for verification, requiring only the public key for validation, enhancing key distribution security.
Key errors, token tampering, algorithm mismatches, and token format errors are common causes of validation failure, requiring step-by-step troubleshooting.
It is recommended to validate JWTs with each API request to ensure token validity. High-frequency validation may consider caching validation results to optimize performance.
Local validation avoids transmitting keys over the network, reducing the risk of leakage, especially suitable for token validation needs in sensitive environments.