Metaswitch cleared by FBI for spying

[Ralf-Philipp Weinmann]

On Sat, 12 Apr 2003 10:59:19 -0400
John Kelsey <kelsey.j at ix.netcom.com> wrote:

> At 04:53 AM 4/12/03 +0200, Thomas Shaddack wrote:
> ..
> >Something like an embedded computer, dedicated to PGPfone-like
> >device, using a cellphone as its communication unit. Basically, an
> >embedded computer, with audio I/O on one side and audio I/O and
> >serial port on the other one. The unit would connect between the
> >phone and either a hands-free or a handset/headset, acting either as
> >an encryption/decryption device (and using the phone in data-call
> >mode), or as just a passthrough(for nonencrypted ("plainsound"?)
> >calls)).
> 
> I wonder how hard it will be to just implement encryption in software
> on the phone.  Does anyone know if these relatively new PDA-phones
> have the ability to process the packets they receive from digital
> calls before feeding them into the codec, and the codec outputs before
> they send them out over the air?
> Or just to set up a data-only call where you're just sending bits
> to/from Nautilus or some similar program?

I doubt you can get at the raw packets coming out of the GSM codec and
going to the modem without some serious mangling of the phone's
firmware. Initiating data-calls which then carry the encrypted voice
packets seem like a much more feasible idea. From what I've heard, some
of the recent crop of PDA phones, notably the Nokia 7650 and the
Sony-Ericsson P-800, contain an ARM-9 core with a clock speed above 100
MHz, which might just be sufficient for getting encrypted voice
communications on these gadgets of the ground. This of highly course
depends on how much cycles your voice codec chews. Seeing that both
phones run under Symbian OS 6 and 7 respectively you might even get
portability for your application.

Easier still might be porting Nautilus or Speak Freely to the Zaurus or
just using ZMeeting over an IPsec tunnel over a GPRS connection.

Cheers,
Ralf

-- 
Ralf-Philipp Weinmann <ralf at fimaluka.org> 
PGP key info: 1024D/57B6E7DB, 40EACFD75032981B8B11E80EB8CEB11057B6E7DB