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- Newsgroups: sci.crypt
- Path: sparky!uunet!shearson.com!snark!pmetzger
- From: pmetzger@snark.shearson.com (Perry E. Metzger)
- Subject: Re: Encrypted phones, keys, taps, ...
- Message-ID: <1992Nov6.012330.4470@shearson.com>
- Sender: news@shearson.com (News)
- Organization: /usr/local/lib/news/organization
- References: <7742@transfer.stratus.com> <oTyHTB3w164w@k5qwb.lonestar.org> <gilchr.720707142@ee.ualberta.ca>
- Date: Fri, 6 Nov 1992 01:23:30 GMT
- Lines: 40
-
- Someone posted an idea about digitally encrypting phones, cellular
- phones in particular, by digitizing the signal and using a
- conventional end to end cryptosystem, following which we got this...
-
- gilchr@ee.ualberta.ca (Andrew Gilchrist) writes:
- >
- >The system you describe cannot be implemented on current cellular
- >phone systems in real-time.
-
- Mr. Gilchrist is rather mistaken.
-
- In fact, you can buy systems to digitally encrypt your cellular
- communications right now. AT&T sells such a unit, for instance,
- although they will only sell the ones that use really good encryption
- to Government agencies. The unit in question is just one of their
- normal units for digital encrypted telephony over normal phone lines
- with a cellular transmitter attached.
-
- There is nothing infeasable about building encrypted phone units.
- Modems now hit 14 kilobaud and even higher with the new V.Fast units
- in test (24kbaud is my understanding), whereas excellent voice can be
- transmitted digitally over a 9.6kbaud bandpass given modern
- compression techiques like CELP (codebook excited linear prediction).
- Given the ability to digitize voice in real time and compress it down
- so it needs low bandwidth, all one need do is apply an encryption
- system (most conventional cryptosystems work orders of magnitude
- faster than is needed even on wimpy hardware) and squirt the signal
- out a V.32bis or similar modem, and, voila, encrypted telephony, and
- in real time.
-
- >A standard phone scrambler would be much easier to get/use/etc.
-
- If "standard" means analog, well, analog phone scramblers are almost
- all easily broken, and are pretty poor in general. Why use one when
- digital techniques that are virtually unbreakable are available?
- --
- Perry Metzger pmetzger@shearson.com
- --
- "They can have my RSA key when they pry it from my cold dead fingers."
- Libertarian Party info: Phone 1-800-682-1776, E-Mail 345-5647@mcimail.com
-