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Newsgroups: sci.crypt,alt.privacy.clipper
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From: smb@research.att.com (Steven Bellovin)
Subject: Re: (new) reason for Clipper alg'm secrecy
Message-ID: <1993Apr21.195023.5226@ulysses.att.com>
Date: Wed, 21 Apr 1993 19:50:23 GMT
References: <X9D92B4w165w@tacobel.UUCP> <1993Apr20.155924.29995@news.clarkson.edu>
Organization: AT&T Bell Laboratories
Lines: 31

In article <1993Apr20.155924.29995@news.clarkson.edu>, tuinstra@signal.ece.clarkson.edu.soe (Dwight Tuinstra) writes:
> First, note that the "experts" will only look at "details", and of just 
> the algorithm:
> 
>     In addition, respected experts from outside the
>     government will be offered access to the confidential details of
>     the algorithm to assess its capabilities and publicly report
>     their findings.
> 
> Why not the chip design?  Well, here's the possiblity:  in addition to
> encryption, the chip pre-processes voice signals to make them easier
> to analyze/transcribe electronically.  The chip, once widespread, might
> effectively be part of a massively parallel computer for "voice-
> grepping" the US phone network (or the criminal & wrong-thinking patrons
> thereof).

First of all, the chip doesn't do that.  It runs at 16 megabits/second,
which is far beyond what you need for voice.  It's obviously intended
for data as well, and on high-speed lines at that.

Second -- what advantage is there to doing the processing in the phone?
I don't care how fancy that chip is; it's not as fancy as the roomful
of analyzers at Fort Meade running the program they'll have 5 years from
now.  They can't update every Clipper chip that's out there.

Third -- if they did do this preprocessing in the chip, it would probably
have a serious effect on recognizability of the voice patterns.  If
nothing else, that would hurt the acceptability of the product.  The
V.32bis modems are just barely fast enough to do a good job on properly-
massaged voice as is; add any more to the mix, and you're completely out
of the ballpark.
