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The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:19:15 ADT
Bill Sommerfeld (sommerfeld@orchard.arlington.ma.us)
Tue, 30 Jun 1998 11:01:53 -0400
> >I'm actually under the impression that using a truncated hash output
> >in lieu of the hash produces a more secure result under many
> >circumstances.
> >
>
> No. Hashes do not have perfect random output. If you truncate the output
> you will introduce vulnerabilities not anticipated by the designer.
It depends on whether you're using the hash as a hash, or as a
building block in a MAC. In the former case, truncation reduces
security.
In the latter case (which, if I'm not mistaken, is what Perry was
referring to), truncation may *increase* security against key-recovery
attacks, because for any given (<message>,<MAC>) pair, it increases
the number of possible keys which could have generated the given MAC
from the message.
- Bill
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:19:15 ADT