From: Adam Back <aba@dcs.ex.ac.uk>
Date: Fri, 18 Oct 1996 10:07:39 -0700 (PDT)
To: shamrock@netcom.com
Subject: Re: DES cracker.
In-Reply-To: <Pine.3.89.9610172224.A7082-0100000@netcom9>
Message-ID: <199610180223.DAA00349@server.test.net>
MIME-Version: 1.0
Content-Type: text/plain



Lucky Green <shamrock@netcom.com> writes:
> On Fri, 18 Oct 1996, Geoffrey C. Grabow wrote:
> > Tell me what you need.  A large part of my job is providing hardware
> > security modules to banks to secure (among other things) their ATM networks
> > (Automated Teller MAchines, not Async Transfer Mode).  Do you need PIN
> > encryption formats, transmission message protocols, or what?  Just LMK.
> 
> It would be best to attack something that has broader use than just a 
> single pin. At best, that would allow an hostile to clean out a single 
> account. A target that would allow one to attack, say an account held 
> *by* a bank would be more attractive.

Account transfers was what I had in mind also, the higher value
transactions that they are used for, and the more widely used the
better.  So being able to break the authentication on transmission
message protocols, might be enough, if being able to forge the
authenticed payment transfer requests would be possible.

Any protocols you can point us to involving inter-bank or
international transfers would be great, if there are any which are
still using DES rather than 3DES.

Hope these protocols use include known plaintext, either fixed message
parts, or predictable (account numbers), or use an integrity check
which we can also (ab)use.  (Netscape's SSL used (is this still
present in SSL3.0?) such an integrity check and this was the toe hold
for the SSL brute force.)

(As a fall back, ATMs might be useful if the protocol used the same
key to encrypt all PINs.  However, one might hope that the protocols
use diferent DES keys for different PINs.)

Some time ago, there was a Russian guy with some other accoplices who
got caught transferring several millions out of some US banks, this
was in the news, and some news clips were posted to cypherpunks, but
I've never seen the details of how he did it discussed.  Was this an
inside job, or was it black cryptanalysis?

Adam
--
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