Phil Zimmermann

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Philip R. "Phil" Zimmermann[2] (born 1954)[1] is an American computer scientist and cryptographer. He is the creator of Pretty Good Privacy (PGP), the most widely used email encryption software in the world.[2] He is also known for his work in VoIP encryption protocols, notably ZRTP and Zfone. Zimmermann is co-founder and Chief Scientist of the global encrypted communications firm Silent Circle.

Phil Zimmermann
PRZ closeup cropped.jpg
Camden, New Jersey, U.S.[1]
OccupationProfessor Edit this on Wikidata
Known forCreator of Pretty Good Privacy


He was born in Camden, New Jersey.[1] Zimmermann received a B.S. degree in computer science from Florida Atlantic University in Boca Raton, Florida in 1978.[2] In the 1980s, Zimmermann worked in Boulder, Colorado as a software engineer and was a part of the Nuclear Weapons Freeze Campaign as a military policy analyst.[3]


In 1991, he wrote the popular Pretty Good Privacy (PGP) program, and made it available (together with its source code) through public FTP for download, the first widely available program implementing public-key cryptography. Shortly thereafter, it became available overseas via the Internet, though Zimmermann has said he had no part in its distribution outside the United States.

In 1995, he published a book "PGP Source Code and Internals", as a way to bypass limitation of exporting digital code. The book contains source code to a software package called PGP[4]

The very first version of PGP included an encryption algorithm, BassOmatic, developed by Zimmermann.[5]

Arms Export Control Act investigationEdit

After a report from RSA Security, who were in a licensing dispute with regard to the use of the RSA algorithm in PGP, the United States Customs Service started a criminal investigation of Zimmermann, for allegedly violating the Arms Export Control Act.[6] The United States Government had long regarded cryptographic software as a munition, and thus subject to arms trafficking export controls. At that time, PGP was considered to be impermissible ("high-strength") for export from the United States. The maximum strength allowed for legal export has since been raised and now allows PGP to be exported. The investigation lasted three years, but was finally dropped without filing charges.

After the government dropped its case without indictment in early 1996, Zimmermann founded PGP Inc. and released an updated version of PGP and some additional related products. That company was acquired by Network Associates (NAI) in December 1997, and Zimmermann stayed on for three years as a Senior Fellow. NAI decided to drop the product line and in 2002, PGP was acquired from NAI by a new company called PGP Corporation. Zimmermann served as a special advisor and consultant to that firm until Symantec acquired PGP Corporation in 2010.[2] Zimmermann is also a fellow at the Stanford Law School's Center for Internet and Society. He was a principal designer of the cryptographic key agreement protocol (the "association model") for the Wireless USB standard.

Silent CircleEdit

Along with Mike Janke and Jon Callas, in 2012 he co-founded Silent Circle, a secure hardware and subscription based software security company.[3][7]

Dark Mail AllianceEdit

In October 2013, Zimmermann, along with other key employees from Silent Circle, teamed up with Lavabit founder Ladar Levison to create the Dark Mail Alliance. The goal of the organization is to work on a new protocol to replace PGP that will encrypt email metadata, among other things that PGP is not capable of.

Zimmermann's LawEdit

In 2013, an article on Zimmermann's Law quoted Phil Zimmermann as saying The natural flow of technology tends to move in the direction of making surveillance easier, and the ability of computers to track us doubles every eighteen months,[8] in reference to Moore's law.

Awards and other recognitionEdit

Zimmermann has received numerous technical and humanitarian awards for his pioneering work in cryptography:

Simon Singh's The Code Book devotes an entire chapter to Zimmermann and PGP.[15]


  • The Official PGP User's Guide, MIT Press, 1995[16]
  • PGP Source Code and Internals, MIT Press, 1995[17]

See alsoEdit


  1. ^ a b c d Garfinkel, Simson (1994). PGP: Pretty Good Privacy. O'Reilly & Associates. p. 85. ISBN 0585032211. OCLC 45730291.
  2. ^ a b c d "Phil Zimmerman's Homepage: Background". Retrieved 2012-01-12.
  3. ^ a b Ranger, Steve (23 June 2015). "Defending the last missing pixels: Phil Zimmermann speaks out on encryption, privacy, and avoiding a surveillance state". TechRepublic.
  4. ^ "Author's preface to the book: "PGP Source Code and Internals"". Retrieved 2020-05-26.
  5. ^ Mollin, Richard A. (2007). An introduction to cryptography. CRC Press. p. 227. ISBN 9781420011241.
  6. ^ Sussman, Vic (March 26, 1995). "Lost in Kafka Territory". US News & World Report. Archived from the original on 16 June 2013. Retrieved 27 May 2012.
  7. ^ "Silent Circle". Silent Circle. Private By Design. Archived from the original on 11 June 2015. Retrieved 25 June 2015.
  8. ^ Om Malik (2013-08-11). "Zimmermann's Law: PGP inventor and Silent Circle co-founder Phil Zimmermann on the surveillance society — Tech News and Analysis". GigaOM. Archived from the original on 2013-08-15. Retrieved 2013-08-20.
  9. ^ 2012 Inductees, Internet Hall of Fame website. Last accessed April 24, 2012
  10. ^ ""Top 50 Tech Visionaries"". Archived from the original on 2008-05-28. Retrieved 2008-05-21.
  11. ^ 25 Most Influential and Innovative Products introduced since the invention of the PC in 1981[permanent dead link]
  12. ^ 35 Heroes of Freedom Archived 2007-09-12 at the Wayback Machine Reason, December 2003 Retrieved April 10, 2007
  13. ^ CRN Industry Hall of Fame Archived 2004-04-05 at the Wayback Machine
  14. ^ "Top 10 Innovators in E-business" Archived 2008-07-24 at the Wayback Machine.
  15. ^ Singh, Simon (2000). The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography (US paperback ed.). Doubleday. ISBN 0-385-49532-3.
  16. ^ Zimmermann, Philip (1995). The Official PGP User's Guide. MIT Press. ISBN 0-262-74017-6.
  17. ^ Zimmermann, Philip (1995). PGP Source Code and Internals. MIT Press. ISBN 0-262-24039-4.

External linksEdit