Re: [saag] Revision of "Attacks on Cryptographic Hashes in Internet Protocols"

Joe Touch <touch@isi.edu> Wed, 14 November 2012 07:35 UTC

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Date: Tue, 13 Nov 2012 23:35:04 -0800
From: Joe Touch <touch@isi.edu>
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Cc: IETF Security Area Advisory Group <saag@ietf.org>
Subject: Re: [saag] Revision of "Attacks on Cryptographic Hashes in Internet Protocols"
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On 11/13/2012 8:24 PM, Paul Hoffman wrote:
> On Nov 13, 2012, at 2:16 PM, Joe Touch <touch@isi.edu> wrote:
>
>> This doc refers to IETF protocols that use hashes, but doesn't discuss any in specific. It also doesn't address how hashes are used, e.g., solo (as a fingerprint), keyed (for authentication and source confirmation), as part of an HMAC, or as part of key derivation.
>>
>> That sort of information might be additionally useful, IMO.
>
> The opposite was decided when we did RFC 4270, of which this is a direct revision. Many protocols use hashes in multiple ways, and trying to list them was considered a distraction. I believe that is still the case.

The doc says directly that the way in which specific hashes are used in 
"many" Internet protocols is safe. Indicating the details of that claim 
is critical to it having *any* weight.

Further, there's a big difference in the way in which hashes are used 
which can be just as important as the use of "better hash algorithms"

Leaving the interpretation of this doc as an exercise to the reader 
renders it inconsequential.

Joe