From: jamiel@sybase.com (Jamie Lawrence)
Date: Fri, 22 Apr 94 10:43:42 PDT
To: perry@imsi.com
Subject: Re: cryptophone ideas
Message-ID: <9404221742.AA02556@ralph.sybgate.sybase.com>
MIME-Version: 1.0
Content-Type: text/plain


At  7:09 AM 04/22/94 -0400, Perry E. Metzger wrote:

>Let me be blunt. You aren't going to deploy a complete new cellular

Do we have to?

>phone system on your own. If you do think you are, you have lost your

Obviously.

>mind. You can't just hack a CDMA or similar phone to make it secure --
>the other end has to be speaking the same protocol. The other end is a
>very expensive station built and paid for by your local cellular
>provider which is unlikely to be easily modified by you the customer.

Obviously.

>You aren't going to be able to run your own cellphone system, either.

Depends on how rich I get soon ;)

>Perry

I am not sure if I am not explaining myself clearly or if you are being
intentionally dense.

The point is that if we know our stuff, have way too much liesure time and
are dedicated to difficult solutions, my cellular and your cellular could
be hacked to make use of the DSP as a co/dec for what ever we wish it to.
The rebroadaster, central switcher, etc have nothing to do with it- they
don't particularly care if they are transmitting ramblings from your mother
or your voice reversed in half second snips or a Madonna song. Obviously,
analog transmission techniques make, say, a PGPPhone unworkable (even is
someone was bored enough to port it to a DSP :), but scrambling and
reassempling an analogue stream has nothing to do with the relay and could
theoretically be performed by the telephones themselves. Note that I am
making no case for this being in the least bit practical- I can think of
much better thigns to do with my time. 

-j