Encrypted calls - Cryptophone.de protocol

sh soeren at heisrath.org
Sat Aug 23 00:16:52 CEST 2008

Hi Mikko!

I'm currently creating the application you've described. I'm (will be)
using HCD (GSM data connections) to deliver encrypted voice data.

I've tried using pulseaudio on the Neo 1973 (haven't got a freerunner)
It turns out it is way too slow. At the moment, I'm using portaudio
because that one is way better documented than alsa (at least for the
full-duplex part).

At the current stage, I can compress the audio data coming from the
microphone with speex, decompress it and the play it back to the

In the weeks to come I'll add AES for encryption and see how to pipe
that data stream through the modem. When it is at the stage where I can
create a stable connection with pre-shared keys, I'll release the first
version to the public.

It will be licensed under the GPL, but at the moment I really need
to make it stable, optimize it and run a few tests before I'll release
it ;-)

Future plans include compatibility with the cryptophone protocol and the
option to use a PKI for session key exchange.

- Soeren

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