Newbee wants to kick start - second try

ramsesoriginal ramsesoriginal at
Sat Apr 26 03:01:48 CEST 2008

If it's like that, then a simple amplitude-modulation over a
pre-recorded, fixed, carrier of the encrypted data should be no
problem, since amplitudes are sent...

On Sat, Apr 26, 2008 at 12:09 AM, Flemming Richter Mikkelsen
<quatrox at> wrote:
> On 4/24/08, ramsesoriginal <ramsesoriginal at> wrote:
>  > On Thu, Apr 24, 2008 at 2:47 PM, Adilson Oliveira
> > >  - - I've being reading about a project to implement cryptography on
>  > >  Openmoko so the calls and text messages can be secured, unfortunately I
>  > >  forgot the name of the project but I've heard that voice calls can't be
>  > >  secured like that due limitations on the way GSM work. Is this correct?
>  >
>  > As far as I understood it, a GSoC-Project is a sms middleware, which
>  > should (theoretically) implement a way to simply encrypt with gpg the
>  > sms. Phone calls can't be encrypted that easilly because, as far as i
>  > understood it, the microphone is connected directly to the gsm chip.
>  > But we have many intelligent people here, so someone will probably
>  > find a way to do even that.
>  The microphone is connected to the sound card:)
>  The reason that encrypted calls over GSM is so difficult, is that the GSM
>  chip samples and encode the input from the microphone. This coding
>  is optimized for speach only and does not actually send your speach
>  over the network, but it breakes the sound up in small parts and
>  use a lookup table to find something that is more or less similar.
>  It then sends the table index over the network. The actual sound is never
>  sent, not even in digital form. This is at least how I remember it
>  --
>  Please don't send me Word or PowerPoint attachments.
>  See
>  Join the FSF as an Associate Member at:
>  <URL:>
>  Free your mind - Open(moko) your phone
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