Re: cryptanalysis for radio communications

[rustman@netcom.com (Rusty H. Hodge)]

sameer@uclink.berkeley.edu says...
> 	I was wondering if any cryptanalysis packages existed which
> could help in decrypted information picked up with a scanner. It seems
> that a bunch of people trying to defend their home from the feds were
> listening in on the feds radio communications, but now they're
> encrypting stuff. It's probably not very strong crypto, maybe just a
> simple XOR.

Actually, Morotola makes some nice DES encryption systems for radio
communications.  Listening to these on a normal scanner, you will hear the
squelch open and a burst of white-noise like sound.  This is the DES
encryption that the feds use.

There are simple frequency inversion systems that are in use by some
agencies, mostly local if any, but there are $25 kits to decode this.

To break the Motorola system, it would not be an easy undertaking.  You
would have to demodulate the digital data stream, figure out the word
sync, and then start analysing.  That assumes that there is no compression
going on!

Maybe you could modify some of the circuits out ther for decoding the cellular
control channel data stream, although that is much slower than this.

-- 
Rusty H. Hodge, Cyberneticist, Futurist   <rustman@netcom.com>