From: jamiel@sybase.com (Jamie Lawrence)
Date: Thu, 21 Apr 94 16:58:58 PDT
To: cypherpunks@toad.com
Subject: Re: cryptophone ideas
Message-ID: <9404212358.AA17368@ralph.sybgate.sybase.com>
MIME-Version: 1.0
Content-Type: text/plain


At  7:38 PM 04/21/94 -0400, Perry E. Metzger wrote:
>Peter Wayner says:
>> How hard is it to reprogram the DSP that comes with a cellular
>> phone right now? I've never opened one up. Can you just unsolder
>> a rom, read it, insert your own code for DH key exchange, add
>> some encryption, burn a new ROM and have a secure phone? 
>
>You would also have to open up the base station for the cell, unsolder
>its roms, read them, insert your own code for DH key exchange, add
>some encryption, and put it back, and I suspect that the cellular
>vendor would get mad at you.
>
>Perry


Aha. here is where you can enlist the hacker community's experience.
Various phreaker types  have been reprogramming thier cellulars for
quite a while- usually to do  free calls instead of encrypted calls,
but the same ideas apply.  I don't know if anyone has done anything
with the DSPs, but there are various files floating around with the
codes to break into debug-mode and such for a while.

Check yer local underground BBS...