Five controls over PDF digital signing in GroupDocs.Signature for Python: SHA-2 digests, the 26.9 refusal to sign with an expired certificate, the allow_expired and allow_not_yet_valid overrides, cryptographic verification, and log levels that filter....Five controls over PDF digital signing in GroupDocs.Signature for Python: SHA-2 digests, the 26.9 refusal to sign with an expired certificate, the allow_expired and allow_not_yet_valid overrides, cryptographic verification, and log levels that filter.