From: pmetzger@shearson.com (Perry E. Metzger)
Date: Fri, 5 Feb 93 18:57:18 PST
To: cypherpunks@toad.com
Subject: Re: CELP speech compression code at cygnus.com:/pub/celp.speech.tar.Z
Message-ID: <9302060139.AA06488@maggie.shearson.com>
MIME-Version: 1.0
Content-Type: text/plain


> From: gnu@toad.com (John Gilmore)
> 
> The code is up for FTP where you-all can get it.  I made both compressed
> and gzip'd versions (gzip gives smaller files than compress, is faster
> to decompress, but slower to compress).
> 
> -rw-rw-r--   1 gnu      cygnus    2571835 Feb  5 16:04 celp.speech.tar.Z
> -rw-rw-r--   1 gnu      cygnus    2099441 Feb  5 16:09 celp.speech.tar.z
> 
> Much of the tar file is samples of compressed and uncompressed speech,
> (used for testing the code).  The actual C code is about 340K uncompressed,
> and there's also a Fortran version in there.
> 
> I have a copy of the actual compression standard, but not online.
> The Information Liberation Front is welcome to a copy -- maybe
> I should just leave it on the table at the next meeting and hope someone
> "anonymously" picks it up and scans it in.  It's public domain, so
> there's no special thrill from liberating it.

It occured to me that some people might not get the significance of all
this, so prehaps I ought to amplify. 

With the ability to compress speech down into the
same baud rate as, say, a V.32 modem, all one would have to do to have
perfectly secure voice communications is replace your phone with a
setup that took in your speech, digitized it, compressed it, encrypted
it, and sent it over the modem to the other side where this would be
inverted. Fast enough software compression of voice would mean any PC 
with a DSP card and a V.32 modem could become an unbreakable scrambler.
The chief problem is that the DSP needed to do decent compression is
very crunchy, and encryption also tends to be crunchy, so there aren't
typically enough cycles on your average PC. Of course, were someone to
commercially market a board that did all this in hardware...

Perry