Proposal Details

I'm working on an implementation of Merkle Tree Certificates, a new type of certificate that combines issuance with certificate transparency in a way that reduces the overall size of the certificate The spec involves a new type of signature algorithm, specifically for the issuer's signature.

crypto/X509.ParseCertificate() successfully parses the certificate, but sets SignatureAlgorithm to UnknownSignatureAlgorithm. Before attempting to validate the Signature, I would like to inspect the raw signature algorithm in order to ensure it is the OID we expect.

Options:

1. Expose the raw signature algorihm as a field in Certificate. Though I don't know enough about X.509 to say if this is a realistic option.
2. Add support for the MTC signature algorithm. Note, however, that the spec is in an experimental phase and the OID has not been finalized.

Related proposal: #75260