Xref: utzoo sci.electronics:8269 sci.crypt:2396 Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!unmvax!ariel!hydra.unm.edu!ee5391aa From: ee5391aa@hydra.unm.edu (Duke McMullan n5gax) Newsgroups: sci.electronics,sci.crypt Subject: Re: Telephone privacy gadgets Add: Cryptography Summary: They're out there, but.... Keywords: Telephone, scrambler, security, secrecy, cryptography, privacy Message-ID: <790@ariel.unm.edu> Date: 19 Oct 89 04:32:45 GMT References: <799@mccall.uucp> <776@ariel.unm.edu> Sender: news@ariel.unm.edu Reply-To: ee5391aa@hydra.unm.edu.UUCP (Duke McMullan n5gax) Organization: University of New Mexico, Albuquerque, NM Lines: 59 In article otto@tukki.jyu.fi (Otto J. Makela) writes: >Preventation: does anyone know of cheap but reasonably reliable scramblers ? Ahhh -- I won't insist that those are mutually exclusive, but.... Cheap and easy to defeat -- sure. There was one in last year's Electronic Ex- perimenters' Handbook (Popular Electronics). It's a simple double-balanced modulator used to invert your voice signal. It's cheap. It's easy to build. It's easy to defeat. Expensive and hard to defeat -- sure, again. There are several manufacturers in the business. A really good one digitizes the voice and performs an en- cryption/decryption in the digital domain. Very, very hard to defeat. Very, very hard to afford without corporate or government funding. Expensive and easy to defeat -- probably. I've heard (that's rumor mill level, so I don't take it too seriously) that some outfits make dippy double-balanced modulators and sell 'em to the marks for kilobucks, then run like hell. I don't know anything about it from personal experience, but still, there are a lot of goniffs in this sort of business. Cheap and hard to defeat -- I don't think it exists, but it could, and the technology is HERE TODAY! It actually wouldn't be hard to integrate the whole schmeer, including D/A, A/D, key management, (en/de)cryption, and an automatic slicer-dicer for carrots all on the same chip. The thing that would make it cheap is volume production, which probably won't happen, at least not soon. Various Government Agencies (read: Big Brother) don't want powerful crypto- graphic technology to get into the hands of T.C. Mits (and, really, I don't blame them) since it would make their job much, much more difficult. The technology is currently there for very secure voice "scrambling", but it is still a mucho bucks proposition. The VGAs can live with this; there just aren't very many of their ENEMIES who have the finances to play with this stuff on any significant scale. Those who do -- the drug "wholesalers", the Mafia and other organized crime, etc. -- are a minority who can be bugged in other ways. What most people don't realize (and I'm sure the VGAs do, but don't like to publicize it -- for obvious reasons) is that anyone with a computer has a very powerful cryptographic device at his disposal. It's not up to doing real-time voice encryption (you need customized & dedicated hardware for that), but if you don't mind communicating in blocks (write a letter, encrypt it, call up your friend, enmodem the message, etc.), it'll work just fine. Use reason- ably sophisticated algorithms, and none of the VGAs will be able to cryptanalyze your stuff effectively. They MAY crack it with other techniques, such as "practical cryptanalysis" -- stealing the key. Physical security is another problem altogether, one you can't ignore. But that, as the textbooks say, is beyond the scope of this discussion. I'm tired; good night. Hope it helps, d "In all levels of life, the sheep are only safe when the wolves are not hungry." -- F.J. Lovret Duke McMullan n5gax nss13429r phon505-255-4642 ee5391aa@hydra.unm.edu