Re: [Cbor] Deterministic CBOR as a possible DISPATCH item

[Laurence Lundblade <[e-mail]>]

Hi Christopher

> On Mar 6, 2023, at 12:44 PM, Christopher Allen <[e-mail]> wrote:
> 
> On Mon, Mar 6, 2023 at 10:23 AM Laurence Lundblade
> <[e-mail]> wrote:
>> the blanket statement that “deterministic CBOR encoding is required for (all) signing (in the known world)”.
> 
> That is not the statement we desire to make.

I thought I’d saw a statement like this from Anders or another. I can’t find it now.

I queried about it because I wanted to understand the thinking behind it and to see if I was misunderstanding something. I’m not out to disagree here, mostly to understand. I have got what I asked for :-)

I was mostly thinking in terms of simple point-point protocols much different than what you are working on.

> 
> That being said, it has some truth under it — I've been struggling
> over the past 6 years with challenges in various W3C communities and
> WGs about using JWT vs. using a graph format, (the original being
> signed RDF, and the latest version being JSON-LD). It has surfaced not
> only in the Verifiable Credentials 1.0 standard (ratified in 2019 and
> modified in 2022), and the Decentralized Identifier standard (ratified
> last year). It continues to be a challenge in the discussions toward a
> VC 2.0 spec just this month.
> 
> Though the problems in the W3C attempts to compromise between these
> approaches are many, one clue to one of the sources of the larger
> problem is your statement:
> 
> On Mon, Mar 6, 2023 at 10:23 AM Laurence Lundblade
> <[e-mail]> wrote:
>> The signature scheme here could be anything that can carry a payload
> 
> Including the payload causes can cause a host of problems. ...

Yes, makes lots of sense.


To come full circle, quoting myself:

> On Mar 5, 2023, at 12:10 PM, Laurence Lundblade <[e-mail]> wrote:
> 
> ….
> 
> There are a few rare cases where determinism is needed for signing:
> 
> 1) The signed data data is not transmitted. It is instead constructed separately by the sender when signing and the receiver when verifying. The Sig_structure internal to COSE is an example of this.

This is kind of the use case you are describing, but your use case is much more complex.


So yeah, agreed that dCBOR is required for what you are doing.

LL