In a major victory for advocates of privacy on the Internet, the Justice Department yesterday dropped its controversial investigation of the author of a computer program used to scramble electronic mail and telephone conversations.
The probe of Phil Zimmermann, a Boulder, Colo., computer consultant who wrote the program he called "Pretty Good Privacy," had become a cause celebre among users of the Internet, the international network of computer systems. His lawyers were informed yesterday by fax that he will not be prosecuted.
For many years, U.S. law has severely restricted the export of equipment and software used to encode communications to foil eavesdroppers, classifying such encryption products as "munitions." The government fears that the spread of unbreakable codes will hinder the National Security Agency, the code-breaking and eavesdropping agency at Fort Meade, in its gathering of intelligence around the globe.
After Mr. Zimmermann's program was posted on the Internet in 1991 by a colleague acting with the author's approval, federal prosecutors in San Jose, Calif., opened a criminal probe of the computer consultant.
The prosecutors reasoned that by making PGP, as it is known, available on the Internet, Mr. Zimmermann was in effect "exporting" the program without the required license. Anyone in any country who has a computer, a modem and access to the Internet can download the program and use it to encrypt messages.
But computer privacy advocates argued that it is folly to try to stop the spread of software that can move invisibly among the millions of computers around the world linked by the Internet. They maintained that unbreakable encryption is crucial to protect the privacy of electronic mail and such sensitive communications as credit card numbers and bank account information.
"I'm greatly relieved," Mr. Zimmermann said last night from his Boulder home.
"There was a time in a bygone era when it made sense to have controls on this technology, when computers were based on vacuum tubes and filled whole buildings. Today we live in the information age, and we can't function in the information age without cryptography."
In addition to its basic use to scramble e-mail, a newer version of Pretty Good Privacy, called "PGPfone," can be used to encrypt voice conversations over the Internet.
"It turns any PC or Mac [Apple Macintosh computer] into a military-grade secure phone," Mr. Zimmermann said. The PGPfone software, like the original version, can be acquired free from the Internet.
David Banisar, an attorney and activist at the Electronic Privacy Information Center in Washington, called the investigation of Mr. Zimmermann "a four-year harassment" and its conclusion "long overdue."
"He did nothing illegal. He just got in the way of NSA," he said.
Mr. Banisar said the decision may be based on political as well as policy considerations: "They'd already made Phil a folk hero. Turning him into the first Internet martyr wouldn't have helped their cause."
William P. Keane, the assistant U.S. attorney in San Jose who led the investigation, cautioned against too broad an interpretation of the decision to drop the probe.
"If anyone chooses to interpret this as giving free rein to use the Internet for the export of controlled items, including encryption, they do so at their own risk," Mr. Keane said.