Re: Selective Disclosure

On 5/17/19 10:52 AM, Brent Zundel wrote:
> I am already working on this for the implementation guide. I will add 
> the third method to my section on subjective disclosure, and welcome 
> feedback on the PR. (It is not complete, but I raised a PR for the 
> express purpose of obtaining early feedback).
> https://github.com/w3c/vc-imp-guide/pull/14

When adding the third method, I recommend saying there are a number of
potential mitigation strategies for the preimage attack/brute force
problem, including using salts or VRFs
(https://en.wikipedia.org/wiki/Verifiable_random_function). This is just
so it's clear that we're not saying there's only one solution or that
we're recommending any particular solution, rather that there is a
problem for which some solution should be considered.

> 
> On Fri, May 17, 2019, 08:41 Kyle Den Hartog <kdenhar@gmail.com 
> <mailto:kdenhar@gmail.com>> wrote:
> 
>     The third option is something I haven't heard of as an approach to
>     selective disclosure. I like the idea of adding both in as methods
>     of supporting selective disclosure in multiple ways.
> 
>     When writing specs to this do we highlight concerns with particular
>     approaches? Particularly one of the concerns I had with this is that
>     by sharing even a hash, it creates the potential for data to be
>     brute forced. This is easily solved with adding a salt and only
>     providing the salt when revealing the data. Would we want to include
>     something like this to heed potentially less private implementations?
> 
>     *Kyle Den Hartog*
>     Personal Blog <https://kyledenhartog.com>
> 
> 
>     On Fri, May 17, 2019 at 8:00 AM David Chadwick
>     <D.W.Chadwick@kent.ac.uk <mailto:D.W.Chadwick@kent.ac.uk>> wrote:
> 
>         Dear All
> 
>         selective disclosure is clearly an important feature of VCs,
>         e.g. for
>         driving licenses or passports we might only wish to reveal our
>         name and
>         nothing else. There are several potential ways of doing this, viz:
> 
>         i) use of ZKPs - zero knowledge proof algorithms allow
>         assertions to be
>         made about the VC, without revealing the VC itself
>         ii) use of atomic credentials - each property of the credential is
>         issued as a separate VC so that the holder can reveal individual
>         properties
>         iii) use of hashes - The VC only contains hashes of each of the
>         credential subject's properties, and the properties are
>         separately held
>         by the holder. The holder places the to-be-revealed property in the
>         Verifiable Presentation and the verifier computes its hash and
>         compares
>         it to the appropriate hash in the VC.
> 
>         Only the former is mentioned in the data model and neither of the
>         latter, whereas the latter 2 are less computationally intensive to
>         support and might be preferred by implementors. Can we add a
>         section on
>         this to the Implementors Guide
> 
>         thanks
> 
>         David
> 
> 
> 
> 
> 
> 


-- 
Dave Longley
CTO
Digital Bazaar, Inc.
http://digitalbazaar.com

Received on Friday, 17 May 2019 15:03:32 UTC