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secure phone

Secure Analog Telephone Communications using Digital Technology"
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(+3, -1)
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There have been many advances in voice encryption for VOIP, but it seems like landlines have been ignored, ever since PGPfone, which is ancient at this point. It seems to me it should be possible to encrypt landline communications using existing technology and strong ciphers (eg. AES, RSA, Twofish) between a very small group of people. Granted, I have little use for this, but it just seems like a cool idea. Here's how I envision it:

1. The participants of the secure landline conversation would first generate RSA keypairs and distribute their public keys.

3. The phone jack would lead to a modem, which would go into the computer at a USB port. Another USB port would connect to a handset.

2. SSH (or some other crypto software) would be set up to decrypt data coming from the speaker wire using your private key and encrypt data coming from the mic using the public key of whoever you're conversing with. Somehow the speaker wire and mic wire would be soldered to the USB connection in such a way that they could be distinguished from each other, so full-duplex communications could be acheived.

As you can see, my understanding of this is really vague. Maybe USB wouldn't be the best connection technology. And, doubtless, there would be many other issues, notably in the software architecture, to account for authentication and error correction, etc.

Alex Yeh, Nov 09 2006

Here's one. http://www.tccsecure.com/csd3600.htm
[Shz, Nov 10 2006]

CryptoPhone http://www.cryptoph...s/CP-WIN/index.html
Windows client; uses landline, not VOIP [jutta, Nov 10 2006]


       //it seems like landlines have been ignored, ever since PGPfone, which is ancient at this point.//   

       Nope. There are many devices to do this, full-duplex, with keys even. I know of none that connect as described, though.
Shz, Nov 10 2006

       That's pretty cool. It's not quite what I had in mind, though - my idea is not so much a hardware appliance that encrypts telephone communications - although that is probably faster & easier.   

       My idea is to have the computer do the encrypting, so all one would need is a way of hooking one's phone up to one's computer, and some software that does the encrypting & decrypting. The phone hookups would be easy to find, and the software would be open-source, using already existing crypto software and libraries.
Alex Yeh, Nov 10 2006

       It would certainly be less expensive that way. Similar configurations exist, but they are VOIP.
Shz, Nov 10 2006

       Good find, jutta. I thought they bundled a modified O/S, so requiring a dedicated machine, but that's only for their Smartphone implementation. A nice (non)feature: No key escrow!
Shz, Nov 10 2006

       [re: jutta] They say other ports are on the roadmap, too. Neato!
Alex Yeh, Nov 13 2006

       Isn't this just VOIP? Well, it doesn't have to use IP, eliminating some of the overhead, but it's still digital voice over a computer network.
Aq_Bi, Nov 14 2006

       //[Aq Bi] Isn't this just VOIP?//   

       No; VOIP, even dialup VOIP, is eventually routed over the internet, while this (the software thingy jutta linked to, and the gist of my idea) is __analog__ voice routed over the __Plain Ol' Telephone Service__ network. It is only digitized while it is in one's computer, being encrypted.
Alex Yeh, Nov 14 2006


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