Updates for BBS Optional Features

[Wind4Greg]

The IETF drafts for Blind BBS and BBS Pseudonyms have been updated based, in part, on feedback from the verifiable credential community. This has resulted in simplifications of the APIs and feature set. These changes do not affect the "baseline" option for using BBS with verifiable credentials or corresponding test vectors. However, text concerning features needs to be updated as follows:

• Update section 4 "Optional Features": now anonymous holder binding, pseudonyms, pseudonyms + holder binding.
• Update serializeBaseProofValue and parseBaseProofValue
  • Update feature option types to: "baseline", "anonymous_holder_binding", "pseudonym", "pseudonym_holder_binding". We don't have two flavors of pseudonyms any more and want to be able to combine pseudonyms with holder binding.
  • For "anonymous_holder_binding" we no longer need the signerBlind parameter. It's no longer in the Blind BBS API.
  • For "pseudonym" feature option we will now have parameters that look like the "pseudonym_hiden_pid" but with signerBlind replaced by signerNymEntropy
  • For "pseudonym_holder_binding" parameters are the same. Note the verifier behavior will be different.
• createDisclosureData: update step 10. and 11. based on updated feature options and parameters.
• serializeDerivedProofValue: update step 2.3.
• parseDerivedProofValue: update steps 3, 4, and 6.
• Create Base Proof (bbs-2023): update 2nd paragraph on featureOptions to the updated list of features and their names. Also that for pseudonyms signer_nym_entropy is a required parameter.
• Base Proof Serialization (bbs-2023): update first paragraph with updated featureOptions. Update step 4 (and sub-steps) for updated feature options.
• Add Derived Proof (bbs-2023): update featureOption related text.
• Verify Derived Proof (bbs-2023): Update step 6 (and sub-steps) with updated feature options and APIs.

In addition optional feature test vectors will need to be updated.