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Amiga Crypto



 
Return-Path: <[email protected]>
 
>> The basic idea I think would need the following:
>> 
>> - A sound digitizer
>> - High speed modem
>> - 68020 or above processor (for speed purposes)
>> - Good encryption algorithm (IDEA for example)
>> 
>> Implementing the system would involve using the digitizer to digitize the
>> voice. Then processing the sample (in real time) through the encryption
>> algorithm and sending the output to the modem for transmission. The process
>> would be repeated on the other end.
>> 
>> The problems I see occurring are the following
>> 
>> - Speed of the computer affecting real time encryption
>> - Synchronizing the data packets for accurate decryption on the other side.
>> - simultaneous I/O on the serial and parallel ports(for modem and digitizer)
>> - outputing to speakers on receiving end.
>> - having the whole process operate in a full duplex mode (ie. both people
>>   can talk at the same time).
>> 
>> 
>> I think the majority of functions can be handled by the system libraries and
>> outside sources (such as xpkidea.library for encryption).
>> 
>> Does this sound feasible??
 
 
 
[email protected] Writes:
 
>From what I gather CELP takes about 10 to 15 MIPS and LPC takes
>somewhere under 5 MIPS on DSP chips.  Instructions including
>fixed point multiplies and accumulations (not counting divisions).
>Thats quite a load for a 68020 to bear and still do encryption
>and communications isnt it?
 
[Stuff deleted]
 
 
This is true. But if a sampling rate of about 9000-10,000 samples per second
are used this will allow for good voice quality and the encryption algorithm 
should be able to handle it. The IDEA implementations I have seen for the
Amiga run about 30-50K per second on my Amiga 1200 with 68020. This should
be fast enough. If you then can send that data directly to the serial port
with a fast modem 14.4K it should work. But it might sound choppy (haven't
done the figures yet on how much data would be going to the modem while
the person speaks, but it may be substantial enough to make the use of
a high speed modem not feasible. Also I have to consider that data compression
in the form of LAP/M or MNP will be ineffective against the encrypted data
as it will appear as white noise and will be largely uncompressable..
 
 
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