Eli Brandt <ebrandt@jarthur.Claremont.EDU> sent the the following to cypherpunks:
HIGH-TECH SNOOP GADGET. A super-secret branch of the Canadian Security Intelligence Service has awarded three contracts to a Montreal firm to make equipment that can quickly isolate key words and phrases from millions of airborne phone, fax, radio signals and other transmissions. The hardware has the "Orwellian potential to sweep through ... and keep records of all conversations," said one CSIS critic. (CTV National News, 01/31/94 11:00 pm).
Dunno how feasible this kind of keyword recognition presently is, but here's another reason to encrypt.
VERY feasible. The US government has had this technology for several years; the Canadians are just catching up. In the late 80s the US military launched a satellite to spy on the Russians. The satellite was programmed to scan radio transmissions - especially cellular phones - searching for key words which might be related to military or government activities. It seems a few communist party members got a little too confortable with their cellular phones in their limosuines, and spoke very loosely about some secret government projects... They have mentioned this in the series "Space Age" which airs periodically on PBS.