Voice over GPRS?

Ian Stirling openmoko at mauve.plus.com
Sat Feb 3 16:26:55 CET 2007

Crane, Matthew wrote:
> With a point to point link what would be the minimal software stack
> needed?  There's only so much CPU, might it be more appropriate to use a
> relatively lightweight process to rx/tx+encrypt/decrypt the data?  
> In any case, the idea of an open encryption standard for cell phone
> communications is pretty appealing.

Even a really anemic processor can manage AES or whatever at 8Kbit/sec, 
in realtime.
However, as a near-zero CPU option, you could always use one-time-pads 
from the SD.
Key management is substantially more annoying - you need 3M or so of pad 
per person per hour, and you can't reuse it.
However, as long as nobody copies the pad, or compromises the phone, 
it's perfectly secure, even from advances in decryption.
Overwrite the flash several times as the pad is read, and then take out 
and crunch the SD between your teeth if you need to destroy it.
(Your Dental Bill May Vary)

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