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w3c / vc-di-bbs

A linked data proof suite specification for BBS+ signatures
https://w3c.github.io/vc-di-bbs/
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Verifiable Presentation proof specs for BBS #185

Open humayunj opened 3 weeks ago

humayunj commented 3 weeks ago

Current draft lacks a clear specification for verifiable presentations using BBS signatures. The specification should clarify whether the verifiable presentation BBS proof value can only be signed, only be derived, if both options are possible or it's out of the scope of this spec.

msporny commented 3 weeks ago

Current draft lacks a clear specification for verifiable presentations using BBS signatures.

Verifiable Presentations are at a level that's higher up on the stack than just this cryptographic suite (VPs are at the Verifiable Credentials Data Model layer), and how presentations occur are at a higher layer than that (at the VC API or protocol layer).

Derived proofs are provided in these sections:

https://w3c.github.io/vc-di-bbs/#add-derived-proof-bbs-2023 https://w3c.github.io/vc-di-bbs/#derived-proof-security-properties https://w3c.github.io/vc-di-bbs/#derived-proof https://w3c.github.io/vc-di-bbs/#holder-binding-derived-proof https://w3c.github.io/vc-di-bbs/#issuer-pid-derived-proof https://w3c.github.io/vc-di-bbs/#hidden-pid-derived-proof

That said, it would be good to provide some examples of how VPs are done using BBS, there is a section that provides an example here:

https://w3c.github.io/vc-data-model/#example-verifiable-credential-using-the-data-integrity-bbs-cryptosuite-with-a-base-proof

Is something like that what you're looking for?

The specification should clarify whether the verifiable presentation BBS proof value can only be signed, only be derived, if both options are possible or it's out of the scope of this spec.

Presentations only utilize derived proofs, we'll try to make that more clear in the spec.