🚀 go-pugleaf

jon_care@hicom.lut.ac.uk writes:

> 1) Wireless LANS, at frequencies below 10GHz, are easy to monitor relatively
> cheaply. (At the 10Ghz range, one has to intercept the path of the microwave
> signal).

Yes and no. There are LANs operating at 23 GHz that transmit an omni-directional
signal. As you increase frequency it is easier to narrow the beamwidth of a
point-to-point link, however a wireless LAN by definition wants wide area
coverage, not PTP. Even fixed PTP links are easy to intercept.

> Commercial receivers are available that will happily monitor any frewuency
> up to about 950 Mhz - If a TNC (with modem chip set for the correct baud rate)
> is then connected in to a PC, packets received can be decoded and analysed
> very easily.

Well, sort of. This isn't your basic 1200 bps AX.25 packet radio that you find
on 145.01. The 900 MHz systems all run spread spectrum. To intercept a signal
you require the same brand of LAN transciever (or at least one that uses the
same modulation encoding scheme), and you must then determine which particular
spreading code is being used. The former is relatively easy due to the limited
number of products currently available. The latter can be dealt with using a
brute force approach if you're patient.

> An answer to this could be to use some form of publickey encryption.

This is the obvious solution, and a good one. I'm curious why more vendors
don't provide this. Is it simply due to the silly DES export restrictions?

--lyndon