From: gordon@sneaky.lonestar.org (Gordon Burditt)
Subject: Re: Best of Transmissions......
Organization: Gordon Burditt
Date: Tue, 17 Nov 1992 11:31:30 GMT

>> Just ask those who have tried to "break" the DES systems used by 
>> government agencies (like the FBI). The problem with this law is 
>> that it makes some older TVs, a lot of test equipment, and many 
>> scanners now in service technically illegal to use all because the 
>> cellular companies don't want to pay for secure technology but 
>> still want to "claim" security to their customers that isn't 
>> there. If a cellular company went totally encrypted tomorrow, few 
>> of the scanner owners would care, there is more than just cellular 
>> in those ranges.

I'd like to propose that all new digital cellular systems (at least
those part of the public phone system) deployed be required to have 
encryption on the radio-link portion of the call (no cleartext option
available).

Technical details would include:  D-H key exchange, encryption of voice
with DES or something stronger, encryption of control information such
as ESNs, called phone number, and a challenge-response system between the
phone and the cell for validating calls.

Benefits to user:
	Privacy
	Reduced chance of bills due to someone cloning their cell phone ESN.

Benefits to law enforcement:
	Encryption of ESN's sent over the air, and implementing a
	challenge-response system (between the phone and the cell)
	for validating calls should cut down on cellular fraud.
	(Physically stolen phones would still be a problem.  If
	users can tolerate a challenge-response key that has to
	be changed every 6 months, with several weeks of "overlap"
	period during which old and new keys are good, this can
	be reduced.  And, of course, reported stolen phones should
	not be accepted, but the owner could be given a new key
	to use should the phone be recovered.)

	Criminal organizations, such as drug lords, the FBI, the Mafia,
	the NSA, amateur crooks, and local police that don't have
	warrants will not so easily be able to steal credit card numbers
	over the air, get information for blackmail, listen to Dan Quayle 
	or his successors talk about the secrets of the Nintendo in the War
	Room, learn about impending police raids, inside information on 
	companies traded on the stock exchange, keep track of the movements 
	of potential kidnap victims, etc.

	If law enforcement must tap, they can tap at the cell switch.
	With a warrant.  If the cellphone user is moving, they probably 
	have to do this anyway, since they will have trouble getting hold 
	of the radio signal otherwise.

	Law enforcement officers have a greater potential income from
	bribes.  (For information on how government workers take bribes
	to give out government information on people, see the comp.risks
	article on "Operation Private Trust", in which a number of 
	government workers were caught selling information from systems
	such as IRS files, Social Security, etc.)

	Real security in transmissions (from everyone but government and
	those with the money to bribe government workers) will cut down 
	on the deployment of real end-to-end encryption, for such users
	as Senator X who wants to keep his conversations with his
	mistresses from the press, Joe Blow who wants to keep his
	personal business private from his nosy neighbor with the 
	scanner, and Mr. Corporate Executive who wants to talk about
	new products without the competition listening in. 

					Gordon L. Burditt
					sneaky.lonestar.org!gordon
Newsgroups: sci.crypt