Subject: Re: [sipcore] Resend: WGLC: draft-ietf-sipcore-digest-scheme

From: [email-masked] (Dale R. Worley)
Date: Wed, 22 May 2019 22:35:02 -0400

[resent]

Rifaat Shekh-Yusef <[email-masked]> writes:
> I liked your proposed changes; I will incorporate them into the next
> version of the document.

Though I did make a mistake -- RFC 7616 only applies to HTTP, so the
statement in draft-ietf-sipcore-digest-scheme-02 section 2.3 para 2 is
not redundant, even though it appears to be repeating RFC 7616.  Therefore...

>> This suggests the wording could be improved along thse lines (changes
>> marked with "|"):
>>
>>    2.1.  Hash Algorithms
>>
>>    The Digest scheme has an 'algorithm' parameter that specifies the
>>    algorithm to be used to compute the digest of the response.  The IANA
>>  | registry named "Hash Algorithms for HTTP Digest Authentication"
>>  | specifies the algorithms
>>  | that correspond to 'algorithm' values.
>>
>>    [RFC3261] specifies only one algorithm, MD5, which is used by
>>    default.  This document extends [RFC3261] to allow use of any
>>    registered algorithm.
>>
>>  | [RFC7616] specifies the usage preference when a response
>>  | contains multiple challenges specifying different algorithms.  That
>>  | specification is not changed by this document.

The above sentence is incorrect.  I intended it to replace the current
para 3 of the section, and it would be good to replace para 3 with
something correct that clarifies the same question.  Perhaps something
like

   A UAS prioritizes which algorithm to use based on the ordering of the
   challenge headers in the response it is processing.  That process is
   specified in section 2.3 and parallels the process used in HTTP
   specified by [RFC7616].

>>    Note that [RFC7616] defines a -sess variant for each algorithm; the
>>    -sess variants are not used with SIP.

Dale