Re: [PROPOSED WORK ITEM] W3C-VC-QP - Verifiable Credential Quantum Proof #247

Mike:

> This statement:
> > Currently no QP signature offers zero-knowledge proof or 
> unlinkability features, so part of the task of the WG might involve 
> combining QP signatures with more privacy-enhancing signining 
> algorithms (such as BBS or ECDSA-SD).
>
> Is somewhat concerning - combinations / hybrid schemes are non-trivial 
> and I would personally recommend following CFRG, and also SAAG / PQUIP 
> (and also JOSE / COSE) for challenges that are arising in that area 
> and avoid defining any hybrids in a group that does not have the 
> expertise to review the side effects of that combination.
No comment from me on this (maybe Manu knows more?)
> Also, bear in mind that from a review standpoint, more focus is being 
> put on review of KEMs and providing protection around store now, 
> decrypt later attacks in relation to hybrids than on the signature 
> side (since you can sign multiple times with different algorithms).

About KEMs: with Zenroom we also support Kyber512 (also from PQClean) 
and NTRUP761 (the one implemented in openssh). We discussed the topic 
(in a private thread) only to come to the conclusion that we can't see 
an immediate application of KEMs in the VC space. If you have ideas on 
how use KEMs in VCs, I'm all ears!

>
> If you mean multiple signatures - e.g. one BBS+ for selective 
> disclosure, etc, and one for post quantum support then i think that is 
> ok to note.

this is in fact a topic for discussion. Dilihium2 sigs are very fate 
(some 3KB per sig) so you can't fit many inside a VC. I was thinking it 
could make sense to wrap the whole VC (including BBS/ECDSA sigs) into a 
Dilithium2 sig... but again we've just opened the topic so it's all 
green field here.

Cheers,

| Andrea D'Intino | +45  21 62 79 18 | Project Manager
|https://Dyne.org  think &do tank  | software to empower communities
| ⚷ crypto κρυπτο крипто गुप्त् 加密הצפנה المشفره




>
> On Wed, Mar 27, 2024 at 12:41 PM Andrea D'Intino <andrea@dyne.org> wrote:
>
>     Hi everyone,
>
>     we are seeking feedback on a new CCG Work Item proposal regarding
>     the quantum-prooof signatures for Verifiable Credentials across
>     devices and websites. Please leave your support or concerns here:
>
>     https://github.com/w3c-ccg/community/issues/247
>
>     # New Work Item Proposal
>
>     The proposal is about defining a new specification to define the
>     associated Data Integrity cryptosuite that can be used to
>     construct digital signatures and proofs using quantum-proof (QP)
>     signing algorithms, starting with
>     [Dilithium](https://pq-crystals.org/dilithium/index.shtml).
>
>     The notable feature of this family of signature schemes is the
>     quantum-resistance, according to the [NIST competition
>     results](https://csrc.nist.gov/Projects/post-quantum-cryptography/selected-algorithms-2022).
>
>
>     Currently no QP signature offers zero-knowledge proof or
>     unlinkability features, so part of the task of the WG might
>     involve combining QP signatures with more privacy-enhancing
>     signining algorithms (such as BBS or ECDSA-SD).
>
>     We aim to initially focus on Dilithium2 (as apparently there is
>     the only signature scheme readily available) and progressively
>     extend the specs to accomodate more signature schemes.
>
>
>     ## Include Link to Abstract or Draft
>
>     https://msporny.github.io/di-quantum-safe/#abstract
>
>     * Dilithium signature implementations (C language):
>     [pq-crystals](https://github.com/pq-crystals/dilithium.git),
>     [pq-clean](https://github.com/PQClean/PQClean)
>     * Zenroom implementation of the [Dilithium
>     signatures](https://dev.zenroom.org/#/pages/zencode-scenarios-qp?id=dilithium)
>
>     * Specification of _did:dyne_ W3C-DID method supporting [Dilithium
>     pubkey](https://dyne.org/W3C-DID/#dilithium2verificationkey)
>     * Curl POST to test W3C-VC-QP signing
>     [API](https://pastebin.com/h1vWd8eP)
>     * Preliminary W3C-VC-QP proof structure:
>
>     ```
>     "proof": {
>           "created": "1710861739438", //epoch
>           "cryptosuite": "experimental-dilithium2-2024", //proposed
>     cryptosuite name
>           "id": "H+4899Oefjch3wmRTfczR08jSNdJ+Jr67kadQO7/7uc=", //hash
>     of the W3C-VC
>           "proofPurpose": "assertionMethod",
>           "proofValue": "...Dilithium2signature...",
>           "type": "DataIntegrityProof",
>           "verificationMethod":
>     "did:dyne:..#dilithium_public_key"           // Dilithium2 pubkey
>     of the issuer
>         }
>
>     ```
>
>     ## List Owners
>
>     > Identify 1 lead (person responsible for advancing the work item)
>     and at least 1 other owner. Ideally, include their github usernames
>
>     @andrea-dintino @msporny, @jaromil, @wip-abramson
>
>     ## Work Item Questions
>
>     1. Explain what you are trying to do using no jargon or acronyms.
>
>     Draft a standard for a W3C-VC proof format, that supports
>     Dilithium (and potentially further QP algorithms) signatures
>
>     2. How is it done today, and what are the limits of the current
>     practice?
>
>     First experiment of Dilithium signed W3C-VC formats.
>
>     4. What is new in your approach and why do you think it will be
>     successful?
>
>     Building on top of extending w3C-VC cryptosuite standards, aiming
>     to be as little invasive and disruptive as possible.
>
>     5. How are you involving participants from multiple skill sets and
>     global locations in this work item? (Skill sets: technical,
>     design, product, marketing, anthropological, and UX. Global
>     locations: the Americas, APAC, Europe, Middle East.)
>
>     Initial participant group includes cryptographers and developers
>     from Dyne.org (Netherlands), DigitalBazaar (US) and Will Abramson (US)
>
>     6. What actions are you taking to make this work item accessible
>     to a non-technical audience?
>
>     While the topic is deeply technical, the specification should
>     attempt to provide a gentle introduction to the topic via a
>     non-technical introduction as well as non-technical use cases with
>     imagery that is accessible to the general population.
>
>
>     Cheers,
>
>     | Andrea D'Intino | +45  21 62 79 18 | Project Manager
>     |https://Dyne.org  <https://Dyne.org>  think &do tank  | software to empower communities
>     | ⚷ crypto κρυπτο крипто गुप्त् 加密הצפנה المشفره
>