[2411] in cryptography@c2.net mail archive
Re: Existing digital phone encryption
daemon@ATHENA.MIT.EDU (Phil Karn)
Tue Mar 31 01:01:43 1998
Date: Mon, 30 Mar 1998 21:55:48 -0800 (PST)
From: Phil Karn <karn@qualcomm.com>
To: jsimmons@goblin.punk.net
CC: shamrock@netcom.com, cryptography@c2.net
In-reply-to: <199803310519.VAA16706@goblin.punk.net> (message from Jeff
Simmons on Mon, 30 Mar 1998 21:19:06 -0800 (PST))
IS-54 TDMA encryption is a joke. It consists of a fixed "mask", equal
in length to the vocoder frame, that is XORed with every frame of the
conversation. Think of it as a frame-sized one-time-pad that is reused
for the entire conversation.
Phil
