I agree with John. I think the spec is fine as is, for generating a keyid for a simple jwk.
Adding hash input bytes for keys that may or may not have other uses will add additional/unnecessary complexity.
From: John Bradley <ve7jtb@xxxxxxxxxx>
To: Stephen Farrell <stephen.farrell@xxxxxxxxx>
Cc: ietf@xxxxxxxx; jose@xxxxxxxx
Sent: Monday, June 1, 2015 9:23 AM
Subject: Re: [jose] Last Call: <draft-ietf-jose-jwk-thumbprint-05.txt> (JSON Web Key (JWK) Thumbprint) to Proposed Standard
I understand Stephen’s issue.
However this is intended to be a simple way to generate a keyid value based on a JWK.
I think the document as is accomplishes that.
If we want to generate a keyid based on the SubjectPublicKeyInfo format
from x.509 people should be able to do that based on the existing specs.
We did drop the jkt member from the spec a while ago based on feedback.
Based on some of the discussion on creating a thumbprint from a SPKI there may be a need for better documenting
how to do that. A number of the proposals discussed for doing it without full processing only worked for some key-types.,
however that should be a separate spec.
I think this one is ready to go.
Regards
John B.
> On May 28, 2015, at 2:04 PM, Stephen Farrell <stephen.farrell@xxxxxxxxx> wrote:
>
>
> Hi,
>
> I have one comment on this that I did raise with the WG (the
> thread starts at [1] but the subject lines diverged so it's
> not so easy to follow). At the end of that I think I was
> correctly judged to be in the rough within the WG. I'm
> raising it again now as a last-call comment (and wearing
> no hat) as the issue is really about doing the same thing
> in multiple protocols/WGs, so this could be a case where
> IETF consensus maybe ought win over WG consensus, depending
> on whether folks working on other protocols care or not.
> (And I'm not sure if they do.)
>
> Note that if the draft as-is turns into an RFC it will not
> be the end of the world, so I'd only expect that a change
> would be done if there're a load of people who agree that
> changing is beneficial for some actual use-case they have
> or may have in future. (In other words, I really don't
> expect this change to happen and I do not want it to
> happen on purely theoretical grounds, but I wanted to
> check just in case;-)
>
> So my issue is:...
>
> We have a bunch of other protocols (DANE, CoAP and more)
> in which we use a hash of a public key. In most of those with
> which I'm familiar we use the SubjectPublicKeyInfo format
> from x.509 as the input bytes to the hash function. Doing
> so ensures that a hash generated in one protocol/application
> could in principle be meaningful in others, even if that's
> not a very common thing to want. Note that using that structure
> does not imply anything about using x.509 or asn.1 really as
> pretty much all crypto APIs (or maybe all) provide you with
> a way to extract public keys in exactly that form regardless
> of whether you care about x.509 or anything related to
> that kind of PKI. (So please let's not have the "I hate
> asn.1/x.509/whatever" argument again:-)
>
> This draft defines it's own peculiar input bytes to the
> hash function and even notes that there's no really good
> reason for that difference:-) [2]
>
> I think this would be better if it supported the use of
> hash input bytes that are the same as are used elsewhere.
>
> But, as I said before, the world won't end if this becomes
> an RFC and we have to do another one later on with that
> fairly trivial difference.
>
> Cheers,
> S.
>
> [1] https://www.ietf.org/mail-archive/web/jose/current/msg04954.html
> [2] https://tools.ietf.org/html/draft-ietf-jose-jwk-thumbprint-05#section-5
>
>
> On 28/05/15 17:40, The IESG wrote:
>>
>> The IESG has received a request from the _javascript_ Object Signing and
>> Encryption WG (jose) to consider the following document:
>> - 'JSON Web Key (JWK) Thumbprint'
>> <draft-ietf-jose-jwk-thumbprint-05.txt> as Proposed Standard
>>
>> The IESG plans to make a decision in the next few weeks, and solicits
>> final comments on this action. Please send substantive comments to the
>> ietf@xxxxxxxx mailing lists by 2015-06-11. Exceptionally, comments may be
>> sent to iesg@xxxxxxxx instead. In either case, please retain the
>> beginning of the Subject line to allow automated sorting.
>>
>> Abstract
>>
>>
>> This specification defines a method for computing a hash value over a
>> JSON Web Key (JWK). It defines which fields in a JWK are used in the
>> hash computation, the method of creating a canonical form for those
>> fields, and how to convert the resulting Unicode string into a byte
>> sequence to be hashed. The resulting hash value can be used for
>> identifying or selecting the key represented by the JWK that is the
>> subject of the thumbprint.
>>
>>
>>
>>
>> The file can be obtained via
>> https://datatracker.ietf.org/doc/draft-ietf-jose-jwk-thumbprint/
>>
>> IESG discussion can be tracked via
>> https://datatracker.ietf.org/doc/draft-ietf-jose-jwk-thumbprint/ballot/
>>
>>
>> No IPR declarations have been submitted directly on this I-D.
>>
>>
>>
>>
>
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