Re: [sipcore] Alexey Melnikov's No Objection on draft-ietf-sipcore-digest-scheme-12: (with COMMENT)

["Alexey Melnikov" <[e-mail]>]

Hi Rifaat,

On Wed, Oct 30, 2019, at 9:50 PM, Rifaat Shekh-Yusef wrote:
> Thanks Alexey!
> 
> I am fine with the first two comments, and will fix these in the coming version of the document.
> 
> I am not sure I follow the 3rd one. Why do you see the need for a minimum number of hex digits?
You do say that the number of hex digits match the hash lenght, so it is probably Ok. However empty value is never valid (and I am worried it might hit some boundary condition bug in implementations), so prohibiting it in ABNF would be the best.

Best Regards,
Alexey
> 
> Regards,
>  Rifaat
> 
> 
> 
> On Wed, Oct 30, 2019 at 1:16 PM Alexey Melnikov via Datatracker <[e-mail]> wrote:
>> Alexey Melnikov has entered the following ballot position for
>>  draft-ietf-sipcore-digest-scheme-12: No Objection
>> 
>>  When responding, please keep the subject line intact and reply to all
>>  email addresses included in the To and CC lines. (Feel free to cut this
>>  introductory paragraph, however.)
>> 
>> 
>>  Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
>>  for more information about IESG DISCUSS and COMMENT positions.
>> 
>> 
>>  The document, along with other ballot positions, can be found here:
>> https://datatracker.ietf.org/doc/draft-ietf-sipcore-digest-scheme/
>> 
>> 
>> 
>>  ----------------------------------------------------------------------
>>  COMMENT:
>>  ----------------------------------------------------------------------
>> 
>>  I am agreeing with Alissa's DISCUSS.
>> 
>>  Also, I have a few comments of my own:
>> 
>>  1) Last para of Section 2.1:
>> 
>>  2.1. Hash Algorithms
>> 
>>  A UAS prioritizes which algorithm to use based on the ordering of the
>>  challenge header fields in the response it is preparing.
>> 
>>  This looks either wrong or confusing to me. I think you are just saying here
>>  that the order is decided by the server at this point.
>> 
>>  That
>>  process is specified in section 2.3 and parallels the process used in
>>  HTTP specified by [RFC7616].
>> 
>>  So based on the above, my suggested replacement for both sentences:
>> 
>>  A UAS prioritizes which algorithm to use based on its policy,
>>  which is specified in section 2.3 and parallels the process used in
>>  HTTP specified by [RFC7616].
>> 
>>  2) Last para of Section 2.4:
>> 
>>  If the UAC cannot respond to any of the challenges in the response,
>>  then it SHOULD abandon attempts to send the request unless a local
>>  policy dictates otherwise.
>> 
>>  Is trying other non Digest algorithms covered by "SHOULD abandon"?
>>  If yes, maybe you should make this clearer.
>> 
>>  For example, if the UAC does not have
>>  credentials or has stale credentials for any of the realms, the UAC
>>  will abandon the request.
>> 
>>  3) In Section 2.7:
>> 
>>  request-digest = LDQUOT *LHEX RDQUOT
>> 
>>  This now allows empty value. I suggest you specify a minimum number of hex
>>  digits allowed in the ABNF. Or at least change "*LHEX" to "2*LHEX".
>> 
>>