KEYS TO THE KINGDOM

By MIKE GODWIN

To most private citizens of a certain age, encryption is a term of espionage, redolent of secretly coded messages sent by agents from behind enemy lines. In the modern world of computers, however, encryption -- also known as ``crypto'' -- has moved from the clandestine to the commonplace. The use of sophisticated codes and keys to protect the privacy of electronic exchanges has become the practical equivalent of sending messages by secret-agent courier. In the past year, moreover, encryption has become a code word in itself, representing a raging war that pits government against a broad coalition of private citizens eager to protect their right to privacy.

One recent development helped bring this battle to a head. Powerful encryption software has become remarkably cheap and accessible, enabling anyone with a home computer to encode messages so effectively that even the National Security Agency's supercomputers may not be able to read them. One favorite is Boulder, Colorado, programmer Phil Zimmerman's PGP, for Pretty Good Privacy, free to anyone in the U.S. who wants to download it from the Internet or from non-Internet-connected BBSs that carry it.

The proliferation of such programs has wrought panic among law-enforcement officials and their brethren in the military and intelligence communities, who see it as a serious threat to their ability to police computer crimes and espionage. The U.S. government is trying to suppress development of such unbreakable encryption on two fronts. It is promoting public use of its own approach to the technology, called ``key-escrow encryption,'' which would allow the government to hold keys to any and all encrypted communications. Washington is also vigorously enforcing a ban on the export of encryption software, regardless of whether such software can thwart government operations from outside U.S. borders.

Privacy advocates say the public's need for encryption tools is greater than ever. ``E-mail messages are just too easy to intercept and scan for keywords,'' Zimmerman told a congressional committee in 1993. Such surveillance, he warned, ``can be done easily, routinely, automatically and undetectably on a grand scale.'' Other experts argue that the government's case is vastly overstated. ``The number of crimes in which encryption is going to be used is infinitesimal,'' says criminologist Jim Thomas. Advocates on both sides of the debate argue with conviction that their view is in the best interests of a healthy democratic society. To be sure, safety and stability remain important components, but so too is privacy. Citizens who have watched as computers have made possible all manner of intrusion into their lives are likely to welcome a piece of technology that enables them to take some of that privacy back. M.G.