From: smb@research.att.com
Date: Wed, 16 Feb 94 08:10:14 PST
To: Eric Blossom <eb@srlr14.sr.hp.com>
Subject: Re: Clipper and Traffic Analysis
Message-ID: <9402161610.AA10454@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


	 
	 > Also, it probably goes via a different physical path.  And at least 
	some
	 > SS7 trunks are encrypted with DES.

	 Care to say anything about which ones are encrypted and why? 
	 Or to ask it another way, who decides?

I phrased it that way because I'm not certain of the extent, and I'm
not certain how much of what I know is AT&T-proprietary.  But the
obvious risks that encryption avoids are traffic analysis by enemies
(pick your own definition of enemy), information on what channels to
wiretap (remember the furor a few years ago about the location of the
then-Soviet embassy on a hilltop in Washington, D.C.?), and the threat
of phone-phreaking by introducing bogus call setup messages.  On the
latter point, recall that out-of-band signaling was introduced in part
in response to ``blue boxes'' and other device that exploited in-band
signaling technologies.