From: Phil Karn <karn@qualcomm.com>
Date: Fri, 10 Jun 94 18:52:17 PDT
To: gtoal@an-teallach.com
Subject: Re: The Crypto Home Shopping Network
In-Reply-To: <199406062335.AAA27342@an-teallach.com>
Message-ID: <199406110152.SAA21313@servo.qualcomm.com>
MIME-Version: 1.0
Content-Type: text/plain


>I think RC4 is the 32 bit cypher used in cellular phones throughout
>Europe.  Rumour has it it can be cracked in realtime.  The actual
>cypher is secret though, which makes it *very* interesting that
>it'll be available in a software product.  The phones use custom
>chips...

No, RC4 is not the European cellular phone encryption algorithm, but
that 32-bit figure *has* come up in discussions of what NSA will allow
the carriers to put into next-generation digital cellular telephones.

The fact that NSA lets out RC2/RC4 with 40 bit keys, but is limiting
new algorithms for cellular to 32 bits may or may not say something
about the strength of RC2/RC4.

I believe the current context for the discussions is data services, as
opposed to voice services.  This is of course a tempest in a teapot
since cellular data users will be in a much better position to encrypt
for themselves using whatever algorithms and protocols they like.

The battle for digital cellular voice privacy, on the other hand, was
lost several years ago. And most cellular users will not be in a
position to add their own strong encryption, especially since it
usually requires the cooperation of the carrier.

Phil