Re: Hash function for AVR 8-bit processor

From: David Wagner (daw_at_taverner.cs.berkeley.edu)
Date: 10/27/05 

Date: Thu, 27 Oct 2005 17:50:55 +0000 (UTC)

ikro@ath.forthnet.gr wrote:
>Yes, I guess I could. Is this suggested againsts those I mentioned? And
>in particular is Skipjack-CBC-MAC more efficient than Skipjack in
>Davies-Meyer mode, for hashing ?

A MAC/PRF is easier to build, and will be more likely to be secure,
so that's what I'd use (if I had the choice).

>I realize that TinySec implements CBC-MAC so I guess I
>could use (/modify) that module for my purposes.

That would work.

>What I am trying to do is to authenticate long (variably sized)
>messages sent by the base station to the motes based on an efficient
>public-key scheme.

Then a MAC is exactly what you want. The only reason to build a hash
would be to use it as part of a MAC -- but you might as well go straight
to the MAC and skip the "build a MAC" intermediate step.