Encrypted Cordless phones

_________________________________________________________________
             FROM THE VIRTUAL DESK OF SANDY SANDFORT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
At the Bay Area Cypherpunks meeting, I mentioned two cordless
telephones that encrypt between the handset and the base unit.
Here is some information about them.

VTech Tropez 900DX

Transmits signal digitally between handset and base unit on one
of 20 channels in the 900 MHz band.  Automatically selects one of
over 65,000 digital security codes each time handset is returned
to the base unit.  Range is up to 800 meters; with up to 4.5
hours of continuous talk time.  Suggested retail cost is $349.95.
For more information:  Steve Johnson, (503) 643-8981.

PhoneMate 2910

Transmits signal digitally between handset and base unit on one
of 10 channels in the 900 MHz band.  Automatically selects one of
over 1,000 digital security codes each time handset is returned
to the base unit.  Range is up to probably about the same as the
VTech.  No figures are given for talk time.  Suggested retail
price is $219.95.  For more information:  Suzanne Nastaskin,
(310) 314-6649.

Both phones have all the usual advanced features like auto-redial
and such.  Neither company's literature tells what encryption
technology they uses.

 S a n d y
_________________________________________________________________
PLEASE RESPOND TO: ssandfort@attmail.com (except from CompuServe)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

> Both phones have all the usual advanced features like auto-redial
> and such.  Neither company's literature tells what encryption
> technology they uses.

It doesn't much matter; they're using ten- and sixteen-bit keys.  
Assuming it takes some 50 ms to tell voice from the white noise that
a failed attempt will generate, a brute-force attack on these
systems should take under a minute and an hour respectively,
worst-case.  This is hardly rock-solid security; it looks like it
rests mostly on nobody reverse-engineering their algorithm.

>  S a n d y

   Eli   ebrandt@jarthur.claremont.edu