Hi Nat and Mike, Thanks for your attention on this issue. I see the following text in section 3.4:
Note that in many cases, only the party that creates a key will need to know the hash function used. A typical usage is for the producer of the key to use the base64url-encoded JWK Thumbprint value as a "kid" (key ID) value. The consumer of the "kid" treats it as an opaque value that it uses to select the key. Only if multiple parties will be reproducing the JWK Thumbprint calculation for some reason, will parties other than the original producer of the JWK Thumbprint need to know which hash function was used. Would it make the draft clearer if that last sentence were omitted? The way this paragraph reads is such that draft considers and would allow for multiple parties generating key IDs, but then we’re back at not knowing which algorithm was chosen. If that last sentence were omitted, this would be less of an issue. > On Jun 24, 2015, at 3:40 AM, Mike Jones <[email protected]> wrote: > > Hi Adam, > > Thanks again for your review comments. > https://tools.ietf.org/html/draft-ietf-jose-jwk-thumbprint-06 > <https://tools.ietf.org/html/draft-ietf-jose-jwk-thumbprint-06> has been > posted to address them. See sections 3.4 (Selection of Hash Function) and 6 > (IANA Considerations). > > Thanks again, > -- Nat and Mike > > From: Kathleen Moriarty [mailto:[email protected]] > Sent: Monday, June 22, 2015 12:51 PM > To: Mike Jones > Cc: Adam W. Montville; The IESG; [email protected]; > [email protected]; [email protected] > Subject: Re: sector review of draft-ietf-jose-jwk-thumbprint-05 > > Yes, thank you. > Kathleen > > Sent from my iPhone > > On Jun 22, 2015, at 9:18 PM, Mike Jones <[email protected] > <mailto:[email protected]>> wrote: > > I’d be glad to add the explanation below to the draft and to also include an > IANA considerations section that states we are updating the expert review > instructions for a registry, as Jim Schaad had suggested. Chairs and > Kathleen, do you want Nat and I to proceed to publish an updated draft? > > -- Mike > > From: Adam W. Montville [mailto:[email protected] > <mailto:[email protected]>] > Sent: Friday, June 12, 2015 5:07 AM > To: Mike Jones > Cc: The IESG; [email protected] <mailto:[email protected]>; > [email protected] > <mailto:[email protected]>; [email protected] > <mailto:[email protected]> > Subject: Re: sector review of draft-ietf-jose-jwk-thumbprint-05 > > > On Jun 11, 2015, at 4:25 PM, Mike Jones <[email protected] > <mailto:[email protected]>> wrote: > > Hi Adam, > > Thanks for the secdir review. > > > > From: Adam W. Montville [mailto:[email protected] > <mailto:[email protected]>] > Sent: Monday, June 08, 2015 8:46 AM > To: The IESG; [email protected] <mailto:[email protected]>; > [email protected] > <mailto:[email protected]> > Subject: sector review of draft-ietf-jose-jwk-thumbprint-05 > > > > Hi, > > > > I have reviewed this document as part of the security directorate's ongoing > effort to review all IETF documents being processed by the IESG. These > comments were written primarily for the benefit of the security area > directors. Document editors and WG chairs should treat these comments just > like any other last call comments. > > I believe the document is ready with (potential) issues. The “with issues” > might be due to ignorance on my part. The draft does a very good job of > explaining the canonical form of a JSON Web Key that can be used for > establishing a thumbprint under varying circumstances, complete with what I > found to be helpful examples. > > The primary issue I have is that it’s unclear how relying parties are going > to know which hash algorithm has been used. The examples use SHA-256, but > I’m not seeing where SHA-256 might be specified as a MUST or even a SHOULD. > Moreover, the example output ultimately shows only the Base-64 encoding of > the resulting hash, which says nothing about the algorithm used to identify a > key. > > Earlier drafts had included fields whose names were intended to communicate > the information about the hash function used - see the "jkt" field > definitions in > http://tools.ietf.org/html/draft-ietf-jose-jwk-thumbprint-01#section-4 > <http://tools.ietf.org/html/draft-ietf-jose-jwk-thumbprint-01#section-4> - > but several working group reviewers suggested that these fields were > unnecessary and that the typical usage would be as "kid" (key ID) field > values. With that removal, it falls onto the application to specify the hash > algorithm for its particular usage. > > This isn't as bad as you might think, however, because typically the consumer > of the "kid" doesn't need to know the algorithm because it won't be > reproducing the computation. It just relies on the fact that a unique key ID > value was generated for the key and compares "kid" values as opaque strings > to find the appropriate key. In this usage, the producer of the key is the > only party that needs to know the hash algorithm that it is using. I hope > this helps. > > Yes, this does help, thank you. It seems like something that could be easily > added to the draft to explain why the generating algorithm needn’t be > disclosed so that slow folk like myself get the picture straight away. > > > > > > > > Additionally, in Section 4, “JSON and Unicode Considerations” some “should”s > are used, but I’m not reading them as SHOULDs. Should they be SHOULDs? For > example, the start of the third paragraph in that section: “if new JWK > members are defined that use non-ASCII member names, their definitions should > specify the exact Unicode code point sequences used to represent them.” It’s > not clear to me whether this is a strong statement or just a recommendation - > it seems that this draft could help the future by making stronger statements > to encourage future interoperability. > > For the other JOSE specifications, our chair Jim Schaad took the position > that RFC 2119 keywords should be reserved for testable protocol behaviors and > that other uses of the English word "should" should not use "SHOULD". The > authors followed that convention in this document. I do understand that > other authors and working groups have taken different positions in this > regard. If there are particular uses that you still feel should be changed > to use RFC 2119 keywords, please call them out. > > This is all good, too. I was simply pointing out that there are “should”s > around that may need to be considered as “SHOULD”s. I also see Jim’s (and > others’) subsequent notes on the subject, so this is good from my perspective. > > > > > > > Kind regards, > Adam > > Thanks again! > -- Mike
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