Re: radio net (fwd)

[Michael Motyka <mmotyka@lsil.com>]

Hi Bill,

Bill Stewart wrote:

> Not per se, though there _is_ still one major restriction -
> the Defense Department gets a crack at patent applications,
> so if you try to patent a crypto algorithm or crypto phone,
> they can seize and classify your patent application and
> working materials, using the excuse of "national security".
>
I suppose we need more altruistic gestures placing good stuff into the
public domain.

> Sure there are - my $150 cordless phone uses spread-spectrum,
> partly for better sound quality, partly for better privacy,
> and partly because it's simpler than picking individual channels.
>
The security is only between the handset and the base unit. Once the
signal hits the POTS it's the same old story - open line.

ALSO - the channels and the hopping sequence used in the
"spread-spectrum" systems are predefined. Kind of like making a stream
cipher with a very short bitstream you got from the government printing
orifice. Using any other sequence is a crime.

The real purpose of the spread spectrum phones is to allow increased
signal levels. The security is not robust.

Try this one:

Not particularly original - I would guess that Tim's 3DES phone is
something like this.

Wal Mart Plastics for the housing ( ever tooled plastics? $$$ )
Custom board
	Dedicated DSP for voice compression/decompression
	Modem chipset for POTS connect ( direct or ISP )
	Fast microP for encryption/protocol
	Any encryption algorithm you desire
	Software Developer's Kit ( roll your own algorithm )

This will work very nicely at home or with any cell phone that has a
modem port. It's really nothing but a dedicated version of a PC based
PGP phone. It's just smaller and cheaper than a PC and has no MS DLLs on
it.

Regards,
Mike