Re: JSON-LD vs JWT for VC

Just to clarify. I’m not a fan of canonicalization for the reasons
mentioned here, but it could work with proper tooling.

My main problem is that it you have to be intimately  knowledgeable of how
json-ld,  canonicalization and even how did resolution works before you can
safely take a verifiable claim and verify it.

It is even more complex due to the nested aspects of many parts of the
proposed VC standards.

In many cases in its extreme flexibility it has the same very dangerous
aspects of xmlsig.

For VC to actually be used it needs to have tooling that can safely be used
by regular bank or web devs to verify what is sent to them.

Ideally it would be simple enough that we could get a plethora of
implementations as well, but it seems unlikely since it’s fans don’t seem
interested in fixing these aspects in the name of flexibility and
readability.

This is why I propose a workable middleground. Those who believe strongly
in the power of JSONLD invest in useable tooling to make it foolproof.

At the same time those of us that are sceptical work to create better
proposals for VC based on JWT.

Currently the state of libraries for json ld signature validation means
that most of us working on real production apps will not support it.

The problem is not solved by a back and forth sending links on the pros and
cons. I think we’re all aware of them and are past that.

Thanks. Hopefully we can make progress.

Pelle

On Sun, Oct 28, 2018 at 17:04 Anders Rundgren <anders.rundgren.net@gmail.com>
wrote:

> On 2018-10-28 19:37, Dean Kevin Poulsen wrote:
> > Anders,
> >
> > Maybe canonicalization can be eliminated, because the need for
> canonicalization stems from the core issue, which is:
> >   —  The requirement that signed content be modified after being
> signed.
>
> Kevin,
> It is rather the wish using standard JSON tools which (typically) do not
> respect property order that calls for canonicalization.
>
> In the case of JSON-LD it is even worse since the requirement is to verify
> that both sides use the same graph expansion scheme.
>
> I started with building unique JSON tools which preserved property order
> and textual representation of elements.  This worked flawlessly but I had
> to give it up anyway since nobody wanted to change their parser :-( The
> recent draft has a potentially very interesting quality: It can (with ease)
> be implemented as a option in a JSON serializer.  Sorting is a one-liner
> and number serializing is well defined and open sourced.  I use the
> canonicalization scheme for multiple purposes in my applications.  Example:
> https://cyberphone.github.io/doc/saturn/bank2bank-payment.html#userauthz
> (requestHash).
>
> Enveloping and detached signature schemes do not require explicit
> modification of signed data but I stick to enveloped signatures because
> they preserve the structure of the data.
>
> Related discussion in the IETF:
> https://www.ietf.org/mail-archive/web/jose/current/msg05752.html
>
> Regards,
> Anders
>
>
> Then, the receiver is required to recreate the signed content through
> prescribed manipulations.
> >
> > “Seasoned XML developers recalling difficulties getting signatures to
> >     validate (usually due to different interpretations of the quite
> >     intricate XML canonicalization rules as well as of the equally
> >     extensive Web Services security standards)…”
> > — From the introduction to:
> https://tools.ietf.org/html/draft-rundgren-json-canonicalization-scheme-01
> >
> >
> > ------
> > My opinion:  SIGNED CONTENT SHOULD NOT BE MODIFIED AFTER IT IS SIGNED.
> >
> > To simplify the proposal, here's a signed JSON-LD in the existing
> standard and the same signed JSON-LD revised per my proposal:
> >
> >
> > My proposal does two things:
> >
> > 1.  It splits the “proof” array into two arrays:  “proofMetadata” and
> “proofValue”.
> > 2.  It puts the signed content into a “signedContent” array.  The
> “proofValue” immediately follows the “signedContent”
> >
> > This pulls the “proofValue” out of the signed content, eliminating the
> need to modify the signed content after it has been signed (except in the
> case of signature sets, where minimal modification is suggested for
> convenience).
> >
> >
> > —
> > You mentioned that one form of canonicalization doesn’t require the
> signature to be included.  I can’t find that option in the links that you
> sent.  Can you point me in the right direction?
> >
> > Thanks,
> > Kevin
> > [“Dean” is a title, not my name.  :) ]
> >
> >
> >
> >
> >> On Oct 27, 2018, at 11:27 PM, Anders Rundgren <
> anders.rundgren.net@gmail.com <mailto:anders.rundgren.net@gmail.com>>
> wrote:
> >>
> >> Hi Dean,
> >>
> >> I don't completely follow your proposal.  Does it actually remove the
> need for RDF/LD canonicalization?
> >>
> >> Anyway, there are subtle differences between formats and one is if the
> signature parameters should be included or not.  Including them requires
> that the data is modified by the signature and verify process.
> >>
> >> FWIW, this is how my Java verifier code deals with this particular
> topic for JSON Clear text Signatures:
> >>
> >>    // 1. Make a shallow copy of the signature object
> >>    LinkedHashMap<String, JSONValue> savedProperties =
> >>        new LinkedHashMap<String,
> JSONValue>(innerSignatureObject.root.properties);
> >>    // 2. Hide the signature value property for the serializer...
> >>
>    innerSignatureObject.root.properties.remove(JSONCryptoHelper.VALUE_JSON);
> >>    // 3. Serialize ("JSON.stringify()")
> >>    normalizedData =
> signedData.serializeToBytes(JSONOutputFormats.CANONICALIZED);
> >>    // 4. Restore the signature object
> >>    innerSignatureObject.root.properties = savedProperties;
> >>
> >> Regards,
> >> Anders
> >
>
> --
*Pelle Brændgaard // uPort Engineering Lead*
pelle.braendgaard@consensys.net
49 Bogart St, Suite 22, Brooklyn NY 11206
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