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[MINUTES] W3C Credentials CG Call - 2018-04-17 12pm ET

From: <msporny@digitalbazaar.com>
Date: Wed, 18 Apr 2018 16:55:52 -0400
Message-Id: <1524084952140.0.10728@zoe>
To: Credentials CG <public-credentials@w3.org>
Thanks to David Chadwick for scribing this week! The minutes
for this week's Credentials CG telecon are now available:


Full text of the discussion follows for W3C archival purposes.
Audio from the meeting is available as well (link provided below).

Credentials CG Telecon Minutes for 2018-04-17

  1. Introductions
  2. Announcements
  3. Issues List
  4. ZK Lang
  Kim Hamilton Duffy and Christopher Allen and Joe Andrieu
  David Chadwick
  David Chadwick, Arnaud Le Hors, Drummond Reed, Manu Sporny, Kim 
  Hamilton Duffy, Lionel Wolberger, Christopher Allen, Nathan 
  George, Dave Longley, Mike Lodder, Shadan Kam, Heather Vescent, 
  Ted Thibodeau, David I. Lehn, Balázs Némethi, Benjamin Young, 
  Yancy Ribbens, Chris Webber, Jarlath O'Carroll, Greg Linklater

David Chadwick: I will scribe
David Chadwick is scribing.

Topic: Introductions

Arnaud Le Hors:  I've been working on standards and open source 
  development for over 25 years, both as a staff member of 
  standards development organizations (SDO) such as W3C and the X 
  Consortium, as well as a representative for IBM. I'm currently 
  Senior Technical Staff Member (STSM) Web & Blockchain Open 
  Technologies at IBM and part of Hyperledger's Technical Steering 
  Committee (TSC).

Topic: Announcements

Virtual hackathon and credentials outreach planned for this 
If you want to be involved tell ChristopherA when you are NOT 
Decentralised conference is meeting first week of Aug, so 
  outreach may be planned to mesh with this
Midata conference is last week of August in Helsinki

Topic: Issues List

Current work items are listed here 
Christopher Allen: https://goo.gl/ZeyJUS

Topic: ZK Lang

Slides available here 
JanCamenisch gives a talk about the slides
ZKLang is a language for mapping VCs to cryptographic algorithms
Uses zero knowledge proof of knowledge statements
So instead of prooving age is GT 21, because it is a hidden 
  message in an anonymous credential then instead would ask if 
  hidden message m1 contained an interger between 22 and 100
Drummond Reed: Manu, that makes sense to me: that any data 
  external to a credential has a pointer and zklang would treat 
  that pointer as data it describes.
Manu Sporny: Drummond, yes... I'm trying to do a gap analysis 
  between ZKLang and what we'd need to shove into the `proof` block 
  in a Verifiable Presentation (which used to be called a 
  Verifiable Profile).
Kim Hamilton Duffy: Is it clear where the mappings to m1, m2, ... 
  is happening?
Or if hidden message contains date of birth, you would ask if the 
  difference between this and today's date is greater than 21
Lionel Wolberger: Please repost updated link to presentation
All fields in a VC have to mapped down to integers in ZKlang
Christopher Allen: 
Purpose is that the implementor does not need to have any 
  knowledge of the crypto
Christopher Allen: 
By writing the validation in ZKLang, the result will return true 
  or false to the questions being asked
Christopher Allen:  Can we use bullet proofs? [scribe assist by 
  Lionel Wolberger]
Christopher Allen: 
Manu Sporny: Previous attempt at mapping CL Signatures to LD 
  Proofs: https://w3c-dvcg.github.io/lds-pseudonymous2016/#examples
@Manu  At a previous RWOT we tried to map linked signatures to ??
Christopher Allen: Christopher Webber also worked on a 
  preliminary ideas on a predicate language for signatures: 
Nathan George: A note that the issues around types and encodings 
  that are are unaddressed in JSON-LD and the issues with mapping 
  to proof of possession instead of disclosing the signature that 
  we've talked about in the VCWG are relevant to why we have been 
  helping pursue this approach
Note in Slide 15, the prover is what we call the holder
Manu Sporny:  JanCamenisch, Nathan, are we doing anything in our 
  VCWG work that would block ZKLang from working?
Drummond Reed: I like that term: "verifiable presentation object"
Ans: no, our current approach is facilitating it
Kim Hamilton Duffy: When we say "Verifiable Presentation" are we 
  referring to the sort of thing discussed here: 
Nathan George: Agreed, that the "proof request" object is an 
  important part of how our protocol works, but has been out of 
  scope for the VC data model
Manu Sporny: Kimhd, no, nothing to do w/ that issue.
Nathan George: We talk about the protocol negotiating between an 
  offer->request->offer->request->return the object (for both 
  credentials and proofs)
Kim Hamilton Duffy: I can't find anything on "Verifiable 
Manu Sporny: Kimhd, What we call "Verifiable Profile" now is 
  going to change to "Verifiable Presentation" per the VCWG F2F 
Dave Longley: Seeing real examples in JSON-LD (exactly what 
  Verifiable Presentation and Verifiable Credentials could look 
  like with ZKLang) in an issue would be really helpful -- and if 
  there are places where the mapping isn't clear those areas could 
  be marked and others more steeped in the data model stuff could 
  jump in and help
Kim Hamilton Duffy: Ok
Manu Sporny: Kimhd, that's because we suck at writing down issues 
Manu Sporny: Kimhd, I'm going to raise an issue now... and then 
  do a PR.
@Cwebber2 would like more examples to see how this will work in 
  our test suite
Kim Hamilton Duffy: +1 Absolutely true; yes to examples
Manu Sporny: Kimhd, nage: 
@JanCamenisch said he will do this after they have finished the 
  coding and proved that it all works!
Drummond Reed: Yes, it feels to me like zklang is an ideal level 
  of abstraction to enable developers to use ZKP.
@JanCamenisch thinks that the level of ZKLang is about right for 
  this group because it abstracts away all the cryptographic 
Kim Hamilton Duffy: One thing I like about the ZKLang approach is 
  that I can actually envision building tooling to support these 
  types of proofs
Drummond Reed: +1 To Kim's point - you can see how developers can 
  build to this
Mike Lodder: I like to think of those as parameters
Mike Lodder: Which hashes to use, generators, moduli, primitives
@JamCamenisch all the publick paramters are shared between the 
  holder and verifier, but things like private keys remain with the 
@JanCamenisch we should have the spec finished by Q3 this year
Drummond Reed: Really excellent presentation, Jan. Great work!
Thanks a lot!
Many thanks to  @JanCamenisch for his presentation
Received on Wednesday, 18 April 2018 20:56:19 UTC

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