Digital Signatures: Format, Certificate, and Validation Policy Are Not the Same Thing The right move when a digital signature fails validation is don't look at the cryptography first . I know that sounds backwards. If the algorithm is RSA-2048 and the certificate chain is intact, why would validation fail? Because a signature can be cryptographically perfect and still get rejected by the validator. The problem isn't the hash or the private key — it's the format, the wrong certificate, or th...