Philip Zimmermann

Philip R. Zimmermann was born in 1954 in Camden, New Jersey, and earned a B.S. in computer science from Florida Atlantic University in 1978. In the 1980s he worked as a software engineer in Boulder, Colorado, and was active in the Nuclear Weapons Freeze Campaign, an anti-nuclear political movement whose concerns about government surveillance later informed his views on cryptography as a tool for protecting ordinary citizens' privacy.

In 1991, Zimmermann wrote Pretty Good Privacy (PGP), a program combining public-key and symmetric cryptography to let ordinary users encrypt email and files. He released it for free via public FTP and Usenet in June 1991, reportedly motivated in part by concern over a since-abandoned US Senate bill that would have required backdoors in encryption products. PGP spread rapidly around the world, in part because a friend uploaded it to Usenet without Zimmermann's direct involvement in every distribution step.

The Criminal Investigation

At the time, US export regulations classified cryptographic software using keys longer than 40 bits as "munitions," subject to the same controls as weapons. PGP used 128-bit keys. In February 1993, Zimmermann became the formal target of a criminal investigation by the US Customs Service into possible violations of the Arms Export Control Act, on the theory that his release of PGP onto the internet constituted an unlicensed export of munitions to foreign nationals.

The investigation became a rallying point for the broader cypherpunk and digital-rights communities, who saw it as a test case for whether cryptography could be legally suppressed by treating source code as a weapon rather than as speech. Zimmermann never faced trial. In 1995, MIT Press published the complete PGP source code as a printed book, PGP Source Code and Internals — a legal maneuver built on the principle that exporting a physical book is protected by the First Amendment, even though the same code as electronic data was restricted. The book could be scanned or retyped and compiled abroad, effectively routing around export law. In 1996, the government closed its investigation of Zimmermann without filing any charges.

Aftermath and Later Work

Freed of legal jeopardy, Zimmermann founded PGP Inc. in 1996; Network Associates acquired the company in 1997 for roughly $10 million. The PGP product line later passed through PGP Corporation (2002) and was acquired by Symantec in 2010. Zimmermann received the Electronic Frontier Foundation's Pioneer Award and the Chrysler Design Award in 1995, and the Norbert Wiener Award and Thomas S. Szasz Award in 1996. In 2012 he co-founded the encrypted-communications company Silent Circle and was inducted into the Internet Hall of Fame; in 2013 he co-created the Dark Mail Alliance with Lavabit founder Ladar Levison to promote end-to-end encrypted email standards. From 2016 to 2021 he was an associate professor at Delft University of Technology in the Netherlands, and in 2016 he received an honorary doctorate from the Université libre de Bruxelles.

Timeline

• 1954Born in Camden, New Jersey.
• 1978Receives B.S. in computer science from Florida Atlantic University.
• 1991Writes and releases Pretty Good Privacy (PGP) encryption software via public FTP and Usenet.
• 1993Becomes the formal target of a US Customs Service criminal investigation for alleged munitions export violations under the Arms Export Control Act.
• 1995MIT Press publishes 'PGP Source Code and Internals' as a printed book to route around export restrictions; Zimmermann receives the EFF Pioneer Award and Chrysler Design Award.
• 1996US government drops the criminal investigation without filing charges; Zimmermann founds PGP Inc. and receives the Norbert Wiener Award and Thomas S. Szasz Award.
• 1997Network Associates acquires PGP Inc. for approximately $10 million.
• 2002PGP Corporation acquires the PGP product line from Network Associates.
• 2010Symantec acquires PGP Corporation.
• 2012Co-founds Silent Circle; inducted into the Internet Hall of Fame.
• 2013Co-creates the Dark Mail Alliance with Lavabit founder Ladar Levison.
• 2016Becomes associate professor at Delft University of Technology (until 2021); receives honorary doctorate from Université libre de Bruxelles.