Subject: Re: CRAMing for last call

From: Sam Hartman <[email-masked]>
Date: Sat, 02 Oct 2004 14:58:59 -0400

>>>>> "Lyndon" == Lyndon Nerenberg <[email-masked]> writes:

    Lyndon> Finally, we need to address the issue of the MD5 "break."
    Lyndon> I have held off from commenting on this issue until the
    Lyndon> community has seen explicit evidence of the attack, and
    Lyndon> the implications of it. At this point, I don't know if the
    Lyndon> document deserves a writeup on the attack. Theory abounds,
    Lyndon> but I haven't yet seen a practical attack that works in
    Lyndon> the general case. We should at the least make mention of
    Lyndon> what has been discussed, and point to the literature, but
    Lyndon> I don't think the document deserves to discuss all the
    Lyndon> possible attacks. This doesn't mean to discourage anyone
    Lyndon> from contributing text to the Security Considerations
    Lyndon> section (please do).

The security area seems to believe that hmac-md5 is still OK, at least
for now.  Especially since cram-md5 does not require much structure
for the challenge, we should discuss the issue in the security
considerations section.

Will you need agenda time at the next meeting?  If so, can you give an
estimate of how much and what we want to cover?

Thanks,

--Sam

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From: Lyndon Nerenberg <[email-masked]>
Date: Fri, 01 Oct 2004 22:02:54 -0700

Now that 2222bis is close to reality, I would like to push the final 
version of CRAM out as well. The two documents should be able to go 
through together, (I hope) making life easier for the RFC editor.

I have some non-substantive editorial changes that will make the 
document a bit easier to read, but these are not show stoppers. I think 
all of the last round of comments are addressed in the current draft. 
If not, I would like to hear from people, soon.

I would also like to solicit a few additional examples from anyone who 
has implemented CRAM in other than IMAP.

Finally, we need to address the issue of the MD5 "break." I have held 
off from commenting on this issue until the community has seen explicit 
evidence of the attack, and the implications of it. At this point, I 
don't know if the document deserves a writeup on the attack. Theory 
abounds, but I haven't yet seen a practical attack that works in the 
general case. We should at the least make mention of what has been 
discussed, and point to the literature, but I don't think the document 
deserves to discuss all the possible attacks. This doesn't mean to 
discourage anyone from contributing text to the Security Considerations 
section (please do).

The IMAP-EXT list has had recent discussion that points out the 
ambiguity of searching for the space (SP) separator (between the user 
id and the digest) as being the rightmost SP, so I will strengthen that 
text. Any other comments should come forth soon as I would like to run 
out the final draft at the end of next week (Oct. 8) if I can.

Cheers,

--lyndon (editor)