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The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:19:15 ADT
Alex Alten (Andrade@netcom.com)
Tue, 30 Jun 1998 08:56:39 -0700
At 11:12 AM 6/30/98 -0400, Perry E. Metzger wrote:
>
>Alex Alten writes:
>> >> No. Hashes do not have perfect random output. If you truncate the
output
>> >> you will introduce vulnerabilities not anticipated by the designer.
>> >
>> >
>> >As I noted, if you aren't in a situation where birthday attacks are an
>> >issue, some truncation can reduce vulnerability to attacks to
>> >determine the key of the MAC.
>> >
>> As part of my work I have cryptanalyzed several proprietary hashes
>> and I've broken one.
>
>Congratulations. Well, it appears that several people who actually do
>know what they are talking about like Hugo Krawczyk seems to disagree
>with you on this point, which in spite of your work you don't seem to
>understand, so I can only conclude that you continue not to know what
>you are talking about.
>
Perry every time I get into a tit-fot-tat with you I end up wasting
my time. Look, not every hash is equal. You can't just truncate
blindly. You need to understand how the hash is internally constructed
and operates. On paper you may be improving the strength in one area,
even in the limited case you mention above, however in fact you may
have reduced it too much in another. All your comments are based on
what you have read. Have you actually gone and torn apart a hash to
see what makes it tick? Quit this nonsense of Hugo said this and Bart
said that, it makes you sound like a damn novice.
- Alex
-- Alex Alten Andrade@Netcom.Com P.O. Box 11406 Pleasanton, CA 94588 USA (510) 417-0159
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:19:15 ADT