The politics of wiretapping and encryption

This article is excerpted from Privacy on the Line: The Politics of Wiretapping and Encryption, Updated and Expanded Edition, by Whitfield Diffie, vice president and chief security officer, and Susan Landau, distinguished engineer, both of Sun Microsystems. Diffie is also co-inventor of Diffie-Hellman public key cryptography. This excerpt is used with permission of The MIT Press


Control of society is, in large part, control of communication. From the right to assemble enumerated in the U.S. Constitution to the antitrust laws prohibiting competitors from agreeing on prices, there is a tension between the right to communicate and limitations on communication. As society evolves, particularly as technology evolves, the government's power to control communications changes.

Telecommunication, barely a century and a half old, has so transformed society that, for most people in industrialized countries, it is a necessity, not an option. People move thousands of miles from friends and family, knowing that they can keep in touch by phone and e-mail. People telecommute to work or, having commuted to the office, spend the day doing their work via telephone, e-mail and the Web. People order goods from dealers on the other side of the continent by dialing 800 numbers or opening Web pages. For a remarkable range and an increasing number of activities, telecommunication stands on an equal footing with physical communication.

Side by side with the growth of telecommunications there has grown up a major "industry" of spying on telecommunications. Communications interception has played a crucial role in intelligence since World War I, and despite improvements in communication security, it continues to grow. The growth of interception is a consequence of the essential fact that the most important effect of the improvements in communications technology on communications intelligence has been to draw more and more valuable traffic into telecommunications channels. As a result, spying on such channels becomes more and more rewarding for governments, businesses, and criminals.

Imagine three versions of an event, one taking place in 1945, one in 1995, and one in 2005. Each involves a major company with physically separated facilities. In 1945, it starts with a brief call, a minute or two. It invites you to an end-of-year project review. You must take a two-day trip to the Pfister Hotel in Milwaukee. It is a nuisance just before Christmas, but there is no alternative. By 1995, the invitation comes not by phone but by e-mail. The project review is to be conducted by conference call, and the associated final report will be sent to all the participants by fax or email. In 2005, the invitation again comes by e-mail, but now the meeting will take place using Web-based collaboration and conferencing tools.