Investigate if the mu algorithm needs to be added

[davek-at-ibm]

I thought it was mentioned that openssl already supported this. Need to confirm

[martinschmatz]

One of the boundary conditions of the 'normal' FIPS204 ML-DSA standard is that the entire message must be used during signing. This can create problems due to (1) the amount of data that must be sent to a signature service, and (2) breach of privacy/confidentiality if the signature service can't be trusted to keep the message private.

Therefore, the FIPS204 standard allows two methods to use a cryptographically secure digest of the message rather then the message: One is to use the HashML-DSA algorithm (Algorithm 4 in FIPS204), the other is to use an 'injection' of the digest 'at the right place and in the right format' into the ML-DSA processing (Step 6 in Algorithm 7 in combination with step 10 of Algorithm 2). The latter is called muML-DSA algorithm (or similar).

The ML-DSA OpenSSL APIs indeed support both approaches - and the availability of a simplified API to abstract the various (some say complicated) steps required to achieve the "muML-DSA" functionality would be equally beneficial as the present simplification of the HashML-DSA functionality.