Crytpo algorithm?

[Mike Rosing]

Hey guys, (are there *any* women reading this list?) I actually have a
crypto question.

In the TI docs for their Digital Signature Transponder they reference
document number 24-09-05-012 "Digital Signature Transponder Algorithm and
Software Requirements".  This seems to be a trade secret since they say an
NDA is required to get it.

It really isn't anything close to a "digital signature", it's more like a
hashing algorithm.  The key is 40 bits and the result is 24 bits.  The
basic operation is to send a 40 bit challenge and then check the 24 bit
result for a go/nogo final output.

The whole thing runs at 134 kHz, so it shouldn't take much to hack
something up to watch bits fly around.  While this challenge is enticing
because it's so easy with not much effort, it's still easier to ask for
details which might actually be available.

Has anyone seen the actual crypto algorithm used in the TI DST devices?
And how close is it to the Ford Securilock E-PATS system?

Just curious :-)

Patience, persistence, truth,
Dr. mike