ValidateAction validates action signature, checks the signed payload action id matches the action id, checks the agent id match.

ValidatePolicySignature validates policy document signature, overlays with signed configuration returns the policy (with signed data overlaying the original policy), the matching signatureValidationKey The signatureValidationKey parameter can be empty, in that case try to read the key from the policy.protected.signing_key and validate the signature with that key.

ValidateSignature validates the data signature against the signatureValidationKey.