[6427] in cryptography@c2.net mail archive
Re: small authenticator
daemon@ATHENA.MIT.EDU (Rick Smith)
Wed Jan 19 14:08:22 2000
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Date: Wed, 19 Jan 2000 11:13:32 -0600
To: staym@accessdata.com, cryptography@c2.net
From: Rick Smith <rick_smith@securecomputing.com>
In-Reply-To: <3884FC13.5A3@accessdata.com>
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At 04:49 PM 01/18/2000 -0700, staym@accessdata.com wrote:
>I've got something with around 100 bytes of ram and an 8-bit multiply.
>Is there an authentication mechanism that can fit in this?
What types of attacks are you concerned with? That's the main question. If
you have a direct, unsniffable connection from the device to the person
being authenticated, then just stick some secret data in there, and make
the guy provide the secret. Be sure to give him/her a way to change the
secret.
If you're passing the authentication data across a sniffable connection,
then I doubt you have the resources to do unsniffable authentication. That
requires a reasonably strong crypto computation. You can throw some sand in
attackers' eyes by doing challenge/response authentication with weak
encryption, but a determined attacker should be able to recover the secret
from intercepted challenge/response pairs.
Rick.
smith@securecomputing.com
"Internet Cryptography" at http://www.visi.com/crypto/
