Re: [jose] AD review of draft-ietf-jose-jwk-thumbprint-04

[Kathleen Moriarty <[e-mail]>]

Hi Mike,

On Tue, Apr 21, 2015 at 11:22 AM, Mike Jones <[e-mail]>
wrote:

>  Hi Kathleen,
>
>
>
> Thanks for taking the time to review the draft and write up today’s and
> yesterday’s comments.  Replies inline below…
>
>
>
> *From:* jose [mailto:[e-mail]] *On Behalf Of *Kathleen
> Moriarty
> *Sent:* Tuesday, April 21, 2015 7:47 AM
> *To:* [e-mail]
> *Subject:* Re: [jose] AD review of draft-ietf-jose-jwk-thumbprint-04
>
>
>
> Another thing has been bugging me since reading the draft yesterday and
> I'm not sure if this was discussed in the WG or not.  There appear to be
> differences in how a JWT thumbprint is described in the draft.  I'd like to
> see if we can work this out before progress the draft into IETF last call.
>
>
>
> The definition is not entirely clear.
>
> Section 3 clearly states that the required members of the JWT are part of
> the thumbprint.
>
> Section 3.2.2, although the subtitle makes the point that this is about
> why optional members are not included, the following sentence appears:
>
>    The JWK Thumbprint value is a
>
>    digest of the key value itself -- not of additional data that may
>
>    also accompany the key.
>
>
>
> 3.2.2 was included in response to earlier review comments by Jim Schaad.
> It’s there to motivate the particular choices made.  Is there some way in
> which you find 3 and 3.2.2 to be inconsistent?  3 is a positive statement
> about what’s included and the sentence in 3.2.2 that you quoted above is a
> negative statement about what’s not included, but that is consistent with
> the positive statement.  The negative statement is included to help readers
> understand the reasoning.  Is there some way in which you found it
> confusing or misleading?  Is there a particular change you might suggest to
> alleviate your concern?
>
>
It is confusing.  Is this a thumbprint of the JWT or just the key?  If it's
just the key, it should be called a Key thumbprint.  If it is of the JWK
members that includes a key, I'm fine with this being the "JWK
thumbprint".  If it's just of the key, the quoted sentence above is fine,
but if the JWK required members are included and it's not just the key, you
have conflicting statements.


>
>
> Section 3.4 - Why is this allowed?  If it's not in JWT format, it is some
> other kind of thumbprint. You are essentially creating a JWK to have the
> key and required members I am assuming, but that's not clear and this text
> could leave interoperability challenges.
>
>
>
> 3.4 points out that the draft specifies a mathematical computation over a
> key value, which can be performed on any key.  It’s stating what’s
> possible, more than what’s stating what’s allowed.  Yes, you’re right that
> you’d be creating a JWK representation of the key value to create the
> thumbprint.  If a thumbprint of the key is needed, this may be a reasonable
> choice in some application contexts.
>

Again, is this a "Key Thumbprint" or a "JWK Thumbprint".  The draft needs
to be consistent and use the correct term depending on what type of
thumbprint this is.  I'm assuming JWK Thumbprint, that is kind of similar
to a certificate thumbprint in that it's over a full set of data and not
just the key (JWK or certificate in the case of X.509).

I hope that further clarifies why I find the text confusing.


>
> Thanks,
>
> Kathleen
>
>
>
> On Mon, Apr 20, 2015 at 3:23 PM, Kathleen Moriarty <
> [e-mail]> wrote:
>
> Hi,
>
>
>
> Thanks for your work on draft-ietf-jose-jwk-thumbprint-04.  This is the
> last one, right?  Great job getting through the JOSE work!
>
>
>
> I read through the draft and have mostly editorial comments that I'd like
> to see if we can fix.
>
>
>
> Section 2:
>
> The definition needs some tweaking:
>
>
>
>  JWK Thumbprint
>
>       The digest value for a key that is the subject of this
>
>       specification.
>
>
>
> "the subject of this specification" should not part of text for a
> definition.  The definition needs to clearly explain the term without
> having to read the whole specification.  Can you suggest something else?
>
>
>
> Karen relayed text from Jim to me that I like and that will be used to
> improve the definition.  It was:
>
>
>
> “This document defines a method for computing a hash value over a JSON Web
> Key structure.  The document describes what the subset of fields in a key
> to be used are, the method of creating a canonical form for those fields
> and how to convert the resulting UNICODE string into a byte sequence
> appropriate for hashing.”
>

That helps to improve the abstract and introduction, thank you.  How about
the definition of JWK Thumbprint?  It should not include things like "this
specification" or "this document".  It should be a stand alone definition.

>
>
> Section 4:
>
>
>
> Can you break this sentence into 2:
>
> However, 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, particularly in cases in which
>
>    Unicode normalization could result in the transformation of one set
>
>    of code points into another under any circumstances.
>
>
>
> OK
>
>
>
> Can you get rid of the parens around the second sentence?
>
>    Use of escaped characters in JWKs for which JWK Thumbprints will be
>
>    computed should be avoided.  (Use of escaped characters in the hash
>
>    input JWKs derived from these original JWKs is prohibited.)
>
>
>
> OK
>
>
>
> Can you reword this sentence/paragraph?  I had to read it multiple times.
> While I understand what you are saying, it could be easier to read.
>
>    While there is a natural representation to use for numeric values
>
>    that are integers, this specification does not attempt to define a
>
>    standard representation for numbers that are not integers or that
>
>    contain an exponent component.  This is not expected to be a problem
>
>    in practice, as the required members of JWK representations are not
>
>    expected to use numbers that are not integers.
>
>
>
> OK
>
>
>
> General comment, the use of long sentences and frequency of parens make
> the draft more difficult to read.
>
>
>
> Thanks for pointing this out.  I’ll try to keep this in mind.
>

Great, thanks!
Kathleen

>
>
> Thanks!
>
>
>
>                                                             Thanks again!
>
>                                                             -- Mike
>
>
>
> --
>
>
>
> Best regards,
>
> Kathleen
>
>
>
>
>
> --
>
>
>
> Best regards,
>
> Kathleen
>



-- 

Best regards,
Kathleen