Phil Zimmermann

The brochure that the Université libre de Bruxelles printed when it conferred an honorary doctorate on him in 2016 states that he was born on February 12, 1954, in Camden, New JerseyNew JerseyNew Jersey is a state in the eastern United States on the Atlantic Ocean, bordered by New York State, Delaware, and Pennsylvania, with the Hudson River forming its northeastern boundary and the Delaware River its western boundary; its capital is Trenton and its largest city is Newark. One of the original 13 colonies, it became the third state to ratify the U.S. Constitution on December 18, 1787, and its population in the 2020 census (April 1, 2020) was 9,288,994.Open the full entry.⁠[1]

He studied computer science at Florida Atlantic University and received a bachelor’s degree in computer science in 1978.⁠[2][1]

In a 2017 interview with Delta, TU Delft’s news platform, he said that he had majored in physics.⁠[3]

In the essay “The Early Roots of PGP” he recalled that years before developing PGP he had been active in geopolitical issues; in the 1980s he lived in Boulder, ColoradoColoradoColorado is a U.S. state classified as one of the Mountain states, with Denver as its capital. It was admitted to the Union on August 1, 1876, as the 38th state, and its population in the 2020 census (April 1, 2020) was 5,773,714.Open the full entry, where he kept his day job as a software engineer while working almost full time as a military policy analyst for the Nuclear Weapons Freeze Campaign.⁠[4]

He wrote that he served on the speakers bureau of the Union of Concerned Scientists, publicly debated government officials, served as defense policy adviser to candidates in a couple of U.S. House and Senate races, and trained lobbyists; he also managed the development of database software for Freeze Voter, the movement’s political action committee. The Université libre de Bruxelles brochure states that he took part in the Nuclear Weapons Freeze Campaign, became a member of the Union of Concerned Scientists and gave talks in the 1980s on the nuclear arms race and arms control treaties.⁠[4][1]

He wrote that in 1983 he helped organize a human encirclement of the Rocky Flats Nuclear Weapons Plant, that he was arrested twice for civil disobedience at the Nevada Nuclear Weapons Test Site, and that he met Carl Sagan, Martin Sheen and Daniel EllsbergDaniel EllsbergDaniel Ellsberg (1931–2023) was an American military analyst and economist who worked at the RAND Corporation and took part in the Defense Department’s top-secret history of decision-making in Vietnam. In 1971 he gave the study, later known as the Pentagon Papers, to the press; the charges brought against him were dismissed in 1973, and he spent the following decades as a peace and anti-nuclear activist.Open the full entry in jail.⁠[4]

He wrote that in the mid-1980s he taught a military policy course, “Get Smart on the Arms Race,” covering the nuclear arms race, NATONATONATO, the North Atlantic Treaty Organization, is an alliance founded on the North Atlantic Treaty signed in 1949, with collective defence as its core principle. Its political and administrative centre is in Brussels, Belgium.Open the full entry doctrine, kinds of deterrence, mutual assured destruction, arms control and verification, proliferation, the Strategic Defense Initiative, U.S.United StatesThe United States is a federal country in North America made up of 50 states, the District of Columbia as the seat of government, and territories such as Puerto Rico and Guam; its capital is Washington, D.C. The Continental Congress adopted the Declaration of Independence on July 4, 1776. The 2020 census (April 1, 2020) counted a resident population of 331,449,281, and the 435 seats of the House of Representatives are apportioned among the states on the basis of the census.Open the full entry and Soviet forces, command and control, launch on warning, counterforce weapons, power projection, the effects of nuclear weapons, nuclear winter and the effects of the Cold War on Third World foreign policy.⁠[4]

An article written by Noah Shachtman for Wired and carried on the Internet Hall of Fame website states that in the late 1980s and early 1990s he was a Colorado peace activist with a half-written encryption program, and that he and his wife were active in Colorado’s liberal politics.⁠[5]

He wrote that in 1984 he saw the need for a tool to protect human rights overseas and grassroots political organizations at home, which became PGP; he started on its early design, but his peace-movement work delayed most of the development for years.⁠[4]

In his preface to PGP Source Code and Internals he wrote that very little of his original code remains in PGP, mostly the multiprecision integer library that he first wrote in late 1986.⁠[6]

In “Why I Wrote PGP” he wrote that the 1991 omnibus anticrime bill, Senate Bill 266, contained a non-binding resolution that, if enacted, would have required manufacturers of secure communications equipment to insert “trap doors” giving the government access to the plaintext of communications; he wrote that this bill led him to publish PGP electronically for free that year, and that the measure was later defeated after protests from civil libertarians and industry groups.⁠[7][6]

Shachtman’s article states that then-Senator Joe BidenJoe BidenJoe Biden (born 1942) is an American politician and lawyer who served as the 46th president of the United States from 2021 to 2025. He was previously a U.S. senator from Delaware from 1973 to 2009 and the 47th vice president, under Barack Obama, from 2009 to 2017.Open the full entry inserted a few words into an anti-terrorism bill, which Zimmermann felt would weaken private communication, and that this spurred him to finish the software; it states that at the time he had a freelance job and two kids.⁠[5]

In his 1996 Senate testimony he said that he wrote and released PGP before the Senate Bill 266 measure was defeated, because he wanted cryptography to be made available to the American public before it became illegal to use it, and that he wrote PGP using information from the open literature and packaged it for desktop and palmtop computers.⁠[8]

In “PGP Marks 10th Anniversary,” dated June 5, 2001, he wrote that on June 5, 1991, he sent the first release to friends to upload to the Internet: Allan Hoeltje posted it to Peacenet, an Internet service provider for grassroots political organizations, mainly in the peace movement, and Kelly Goen uploaded it to a Usenet newsgroup that distributed source code, marking the posting “US only” at his request, and also to many BBS systems around the country. He wrote that he did not recall whether the Internet postings began on June 5 or June 6, and that in 1991 he believed the tag controlled Usenet routing, recognizing only later that it was an advisory tag with little real effect.⁠[9]

In his thirtieth-anniversary essay of 2021 he wrote that PGP was uploaded to the Internet on June 6, 1991, after he had sent it to a couple of friends for distribution the day before.⁠[10]

He wrote that he missed five mortgage payments while developing the software in the first half of 1991; a week before the release he learned of Privacy Enhanced Mail (PEM), which had several large corporate backers and RSA Data Security behind it, and objected to its use of 56-bit DES, its mandatory signatures and its exposure of signatures outside the encryption envelope; he briefly considered not releasing PGP but went ahead, judging that his design better protected users’ privacy. Shachtman’s article likewise states that he missed five mortgage payments in a row while working on PGP.⁠[9][5]

He wrote that after the release he went back to consulting work to catch up on his mortgage, expecting PGP to need little attention, but public demand drew him back into the project; he assembled volunteer engineers around the world who ported PGP to almost every platform (the Mac proved harder), translated it into foreign languages and helped promote it, and he began designing PGP’s trust model.⁠[9]

In his 1996 Senate testimony he said that PGP was published domestically as freeware in June 1991, spread worldwide and became “the de facto worldwide standard for encryption of E-mail.” A 1994 article in Reason states that after someone posted PGP to the Internet it spread to London and Moscow, and that the name PGP is a homage to Ralph’s Pretty Good Grocery in Garrison Keillor’s Lake Wobegon.⁠[8][11]

He wrote that PGP 2.0 was released in September 1992, fifteen months after PGP 1.0, for MSDOS, several Unix versions, the Commodore Amiga, the Atari and other platforms, in about ten foreign languages, with the trust model essentially in its present form. The thirtieth-anniversary essay states that version 2.0 had much better cryptography and new functionality, including the distributed trust model, and that PGP became the most widely used method of email encryption; Shachtman’s article states that version 2 let users decide in a decentralized way which keys to trust instead of relying on a central certifying authority.⁠[9][10][5]

In his preface to PGP Source Code and Internals he wrote that Peter Gutmann and Branko Lankester contributed much development effort and Jean-loup Gailly contributed his ZIP compression routines, and that Hal FinneyHal FinneyHal Finney (1956–2014) was a software engineer and cryptographer, an early developer of the PGP encryption software, who released the reusable proof-of-work system RPOW in 2004; in January 2009 he ran the Bitcoin software released by Satoshi Nakamoto and received the first Bitcoin transaction.Open the full entry worked on PGP 2.0 but was not named in 1994 because it was not safe for him, as a US resident, to be named.⁠[6]

Shachtman’s article states that he had borrowed the patented algorithms for public-key encryption and that the patent holders believed he had violated their rights.⁠[5]

He wrote that shortly after the release of PGP 2.0 US Customs took an interest in the case. The May 1994 article in Reason states that in February 1993 agents of the U.S. Customs Service visited him about the “export” of PGP, and that under the International Traffic in Arms Regulations cryptographic software is classed as “munitions” and cannot legally be exported without federal permission.⁠[9][11]

Steven Johnson’s article states that in February 1993 two federal agents phoned him about PGP and wanted to visit him in Boulder, that he then hired the criminal lawyer Phil Dubois, and that within months a grand jury was convened in CaliforniaCaliforniaCalifornia is a U.S. state on the Pacific coast; its capital is Sacramento and its largest city is Los Angeles. California was admitted to the Union on September 9, 1850, as the 31st state. Its population at the 2020 Census (April 1, 2020) was 39,538,223, the largest of any state.Open the full entry to examine possible violations of weapons-export law.⁠[12]

The Reason article states that he said he had been informed that he was the primary target of an ongoing federal grand-jury investigation; that in September an unnamed encryption company was served with a subpoena for documents about ViaCrypt, PGP and him from June 1, 1991, onward; and that Assistant U.S. Attorney William Keane, who led the grand-jury investigation, declined to comment on an ongoing case but said there might be “some activity shortly.” The article states that ViaCrypt sold the commercial version of PGP through computer software stores. Shachtman’s article states that a federal grand jury was impanelled in San Jose and that his e-mail records were subpoenaed.⁠[11][5]

The Reason article states that if convicted of “exporting munitions” he could face four years in jail.⁠[11]

In his 1996 testimony he said that for three years he had been the target of a criminal investigation by the US Customs Service, which assumed that laws were broken when PGP spread outside the United States; the thirtieth-anniversary essay states that the investigation was under the Arms Export Control Act. He wrote that the investigation increased PGP’s popularity and helped ignite a controversy that would eventually lead to the demise of US export restrictions on strong cryptography.⁠[8][10][9]

The Reason article states that in October 1993 he addressed a congressional subcommittee, that his attorney was Philip Dubois, and that his lawyers set up a fund to help pay his legal bills. It quotes him: “I didn’t do it to make money,” he says. “I did it to inoculate the body politic.” It also quotes him: “PGP empowers people to take their privacy into their own hands.”⁠[11]

Reason wrote in May 1994 that he was working on a voice encryption system that would turn multimedia computers into secure telephones.⁠[11]

In the preface, written in Boulder in November 1994, he explained that PGP Source Code and Internals, published by The MITMassachusetts Institute of TechnologyThe Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. It received its charter from Massachusetts in 1861, admitted its first students in 1865 and moved from Boston to its present campus in 1916. As of October 2025 it had 11,816 students, and it counts 106 Nobel laureates among members of its community.Open the full entry Press in 1995, contains all of the C source code to PGP; he wrote that PGP 2.6.2 uses RSA for key management and digital signatures, IDEA for bulk encryption, MD5 for one-way hashing in digital signatures and ZIP compression before encryption. His website notes that the book is no longer in print.⁠[6]

He wrote that software on the Munitions List requires an export license, and that the State Department can issue a Commodities Jurisdiction ruling transferring an item to Commerce Department control so that it can be exported legally, as it had already done for Bruce Schneier’s Applied Cryptography, another book containing cryptographic source code; he judged that it would be politically difficult to prohibit the export of a book found in libraries and bookstores, applied for a Commodities Jurisdiction for this book, and noted that its code could be scanned with OCR software. He compared the book to a piece of the Berlin Wall, a symbol of freedom, and hoped that it would help open US borders to the free flow of information.⁠[6]

Steven Johnson’s article presents MIT’s publication of the roughly 600-page book containing the PGP code as a defense of Zimmermann.⁠[12]

In a declaration in Daniel J. Bernstein v. United States Department of State (U.S. District Court for the Northern District of California, C 95-00582 MHP) he stated that, as part of the investigation, on or about November 1994 he was temporarily detained and interrogated about his case by Customs authorities at Dulles airport near Washington, D.C., as he tried to reenter the United States after a speaking tour abroad, and that although Customs knew he was represented by counsel and he repeatedly asked for an attorney, he was denied access to legal counsel during the interrogation. In his preface to PGP Source Code and Internals, dated November 1994, he wrote that he wrote some of it in the air between Bucharest and Budapest, on a speaking tour about privacy in the information age.⁠[13][6]

His lead defense counsel, Philip L. Dubois, announced on January 12, 1996, that on the morning of January 11 he had received word from Assistant U.S. Attorney William Keane in San Jose that the U.S. Attorney’s Office for the Northern District of California had decided not to prosecute Zimmermann in connection with the posting of PGP to USENET in June 1991; Keane’s letter says “The investigation is closed.” U.S. Attorney Michael J. Yamaguchi issued a statement that his office had declined prosecution of any individuals in connection with the posting and would not comment on the reasons.⁠[14]

Zimmermann posted a signed statement to the Cypherpunks mailing list saying that the decision closed a criminal investigation that had lasted three years, and thanked the donors to the Zimmermann Legal Defense Fund and his defense team of Phil Dubois, Ken Bass, Eben Moglen, Curt Karnow, Tom Nolan and Bob Corn-Revere, most of whose work was pro bono; the announcement states that the Electronic Privacy Information Center, the Electronic Frontier Foundation, Computer Professionals for Social Responsibility and the American Civil Liberties UnionAmerican Civil Liberties UnionThe American Civil Liberties Union (ACLU) is a nonprofit, nonpartisan civil liberties organization headquartered in New York City, founded in 1920 by Roger Nash Baldwin and others.Open the full entry provided financial, legal and moral support. He also thanked MIT and The MIT Press.⁠[14]

In his statement he wrote: “Nobody should conclude that it is now legal to export cryptographic software.” He speculated that the government may have declined to prosecute because he had not broken the law, or to avoid a court ruling that posting on a US Internet site is not an “export,” a ruling that the export-control law is unconstitutional, or a public debate over privacy policy; the statement ends: “The price of freedom is not only vigilance but also participation.”⁠[14]

National Public Radio’s Morning Edition aired a story on January 12, 1996, on the Justice Department dropping the case. Delta’s article states that the US government dropped the case in 1996 and then began using PGP itself; Shachtman’s article states that the case was dropped after the export control laws were rewritten.⁠[14][3][5]

After the case was dropped he founded PGP Inc. in 1996, serving as its chairman and chief technology officer.⁠[15][8]

The Blockworks article states that he formally hired Hal Finney in 1996; Finney had worked on PGP officially as a volunteer, partly because PGP was not yet a company and partly to avoid drawing the ire of the US government that had already fallen on Zimmermann.⁠[16]

On June 26, 1996, as chairman and chief technology officer of PGP Inc., he testified before the Subcommittee on Science, Technology, and Space of the US Senate Committee on Commerce, Science, and Transportation in favor of S.1726, a bill to change US export control policy on cryptographic software.⁠[8]

In the testimony he said that human rights organizations use PGP to protect people overseas, naming Amnesty International and the human rights group of the American Association for the Advancement of Science; he said that he gave PGP away “for the good of democracy,” and that people in Eastern Europe understood his concern about government power more readily than some Americans. He quoted an email sent to him in October 1993 by someone in Latvia on the day Boris Yeltsin shelled his own Parliament building, which says PGP is “widespread from Baltic to Far East now.”⁠[8]

In December 1997 Network Associates Inc. (NAI) acquired PGP Inc.; he stayed at NAI for three years as a Senior Fellow.⁠[17][15]

In the 1999 update of “Why I Wrote PGP” he wrote that the Bill ClintonBill ClintonBill Clinton (born 1946) is an American politician and lawyer, a Democrat who served as attorney general and governor of Arkansas and as the 42nd president of the United States from 1993 to 2001.Open the full entry administration abandoned the export control regime in late 1999, allowing strong cryptography to be exported with no upper limit on strength, and credited the change in part to the deployment of PGP and to public and industry pressure; the thirtieth-anniversary essay states that US export restrictions collapsed in 2000 and that Western democracies then dropped their restrictions on strong cryptography.⁠[7][10]

On June 5, 2001, he wrote the tenth-anniversary essay in Burlingame, California, stating that PGP remained just about the only way anyone encrypts email and that a dozen companies were developing products based on the OpenPGP standard, all members of the OpenPGP Alliance.⁠[9]

On September 17, 2001, six days after the September 11 attacks, The Washington PostThe Washington PostThe Washington Post is an American daily newspaper founded in Washington in 1877, known for its role in the Pentagon Papers case and the Watergate investigation. Run by the Meyer–Graham family for eighty years from 1933, it has been owned personally by Jeff Bezos since 2013.Open the full entry reporter Ariana Cha interviewed him about how he felt about the possibility that the terrorists might have used PGP in planning their attack; the article ran on September 21 and said that, as PGP’s inventor, he was “overwhelmed with feelings of guilt.” On September 24 he published “No Regrets About Developing PGP,” writing that he had specifically said to the reporter that guilt was not the case and had her repeat it back to him, that Cha had read most of the article to him by phone before submitting it and that version did not contain the statement, and that the published version was much shorter; he speculated that the editors must have taken inappropriate liberties in condensing his views.⁠[18]

He wrote that he had cried over the human tragedy, not out of guilt over developing PGP; that he felt bad about possible terrorist use of PGP but judged it outweighed by PGP’s value as a human rights tool, and that strong cryptography does more good than harm to a democratic society; and he wrote: “Read my lips: I have no regrets about developing PGP.” He wrote that he would not agree to back doors in PGP, and that after the article appeared he received hundreds of supportive emails, two or three a minute on the day it ran.⁠[18]

In August 2002 PGP Corporation acquired PGP from NAI, and he served as its special adviser and consultant until Symantec acquired PGP Corporation in 2010. Shachtman’s article states that Symantec largely ended the consumer version of the software.⁠[17][15][19][5]

His website states that from 2004 he focused on secure telephony for the Internet, developing the ZRTP protocol and products that use it, including Zfone and Silent Phone.⁠[15][2]

Help Net Security wrote that he had released a public beta of Zfone for Mac OS X and Linux, with a Windows XP version slated for mid-April; Zfone needs no public key infrastructure, certificates, certificate authorities or servers, negotiates keys peer to peer over the RTP media stream rather than through SIP signaling, and works with any standard SIP phone, though calls are encrypted only between Zfone clients; the protocol had been submitted to the IETF as a proposed public standard, and the source code was available for download for peer review.⁠[20]

The Register wrote on May 23, 2006, that a new public beta of Zfone added Windows support, with free betas for Mac OS X, Linux and Windows XP that required registration; Zfone generates a fresh key for each session using Diffie-Hellman, is also offered as a separate download that adds encryption to VoIP programs such as Gizmo and SIPphone, and does not interoperate with Skype, which uses its own proprietary encryption; it does not hide traffic-analysis data such as who called whom and when, but protects the content of conversations; and he hoped to license the technology. The article states that FCC rules under CALEA require VoIP providers to permit lawful interception, but that they did not then cover standalone software like Zfone that encrypts calls between individual computers.⁠[21]

In April 2011 ZRTP was published as RFC 6189, “ZRTP: Media Path Key Agreement for Unicast Secure RTP,” an Informational document by him (listed under the Zfone Project), A. Johnston (Avaya) and J. Callas (AppleAppleApple is a public technology company founded in 1976 and headquartered in Cupertino, California, United States. Its business includes the iPhone, Mac, iPad, wearables, and services such as digital content, payments, and cloud storage. The company builds its product system through in-house hardware, operating systems, and services.Open the full entry, Inc.); it defines ZRTP as a protocol for media path Diffie-Hellman exchange to agree on session keys for unicast Secure RTP in VoIP applications, running on the same ports as RTP and requiring no support in the signaling layer.⁠[22]

A 2015 Silent Circle blog post states that in 2011 Mike Janke, a former U.S. Navy SEAL and security specialist, approached him about a partnership, after which the founding team was formed, with Jon Callas, the creator of Apple’s Whole Disk Encryption, joining as chief technology officer.⁠[23]

VentureBeat wrote in 2014 that he launched the privately funded Silent Circle in 2012, with partners including the PGP co-founder Jon Callas, Mike Janke, Vincent Moscaritolo and Vic Hyder. Dark Reading wrote that he was a co-founder and president of Silent Circle, with Janke as co-founder and chief executive and Callas as chief technology officer; the company was self-funded, had turned away venture capital to stay independent and neutral, and had invested $5 million to $10 million in a custom peer-to-peer network; its products were Silent Phone, the video service Silent Eyes and the text-messaging service Silent Text, with the encrypted email service Silent Mail on the horizon, at $20 per user per month for all four, initially for 3G and 4G Apple iOS devices.⁠[19][24]

On August 8, 2013, Silent Circle shut down its encrypted email service, Silent Mail; TechCrunchTechCrunchTechCrunch is an American technology news outlet founded in 2005 by Michael Arrington and Keith Teare and headquartered in San Francisco; it mainly covers technology companies, startups, and venture capital, and hosts events such as TechCrunch Disrupt. Its ownership passed successively through AOL, Verizon, and Yahoo, and in 2025 Regent announced its acquisition.Open the full entry’s article that day identified him as the company’s co-founder and president and the inventor of PGP. The company wrote on its blog that it had not been asked to provide data to the government but had decided “it is best for us to shut down Silent Mail now”; chief executive Michael Janke said the company was acting ahead of expected government pressure and steering users to its other products. The article states that Silent Circle was moved by Lavabit’s shutdown the same day, and that Silent Phone, Silent Text and Silent Eyes continued to operate.⁠[25]

In 2014 he was inducted into the National Cyber Security Hall of Fame. Delta’s article states that the ceremony was presided over by the NSA director, Mike Rogers; in the thirtieth-anniversary essay he wrote that at the ceremony a member of the HUMINT community thanked him, saying that some of his colleagues were alive because of PGP.⁠[15][3][10]

VentureBeat wrote on August 8, 2014, that he spoke at the Defcon hacker conference in Las Vegas; that Silent Circle’s first customer was KPN, a Dutch mobile and landline carrier, and that its customers included the U.S. military, Special Operations teams in Canada, the United Kingdom and Australia, and the U.S. Congress; that the company then had 100 employees; and that he was working on the Blackphone, which runs the PrivatOS secure operating system. The article states that in 2013 he coined a “law” that technology tends to move toward making surveillance easier and that the ability of computers to track people doubles every 18 months.⁠[19]

The article quotes him: “Our whole reason to exist at Silent Circle is security.” Of Edward SnowdenEdward SnowdenEdward Snowden is a former American intelligence worker and technologist who worked for the Central Intelligence Agency (CIA) and later, as a contractor employee, for the National Security Agency (NSA); in 2013 he gave journalists a large cache of classified NSA documents that set off a series of reports on mass surveillance by the U.S. government, after which he was charged in the United States with theft of government property and violations of the Espionage Act, and he has lived in Russia ever since.Open the full entry he said: “If I ever meet Snowden, I’ll have to thank him for waking everyone up.”⁠[19]

The Université libre de Bruxelles brochure states that he left the United States for Switzerland in 2015.⁠[1]

A Silent Circle blog post of August 10, 2015, states that the company was headquartered in Switzerland with employees in eight countries, serving individuals, businesses and governments in more than 130 countries, and that in early 2015 it bought out the joint venture formed to create the Blackphone.⁠[23]

An October 2015 article by the Financial TimesFinancial TimesThe Financial Times (FT) is a London-based English-language business and financial news organization, known for its salmon-pink newspaper and its motto “Without Fear and Without Favour.” It was owned successively by the British Pearson group and Japan’s Nikkei Inc., and today digital subscriptions are its main source of revenue.Open the full entry reporter Sam Jones, republished by swissinfo.ch, states that he, Mike Janke and Jon Callas ran the Swiss-based company together in Geneva, that the first Blackphone sold out within weeks of its release in 2014, and that the second model had been released the month before the article. In the article Janke said that 41 of the top 50 companies of the Fortune 500 were clients, that about 90% of the US Senate used its products, that the company supplied the FBIFederal Bureau of InvestigationThe Federal Bureau of Investigation (FBI) is the federal investigative agency of the U.S. Department of Justice. It grew out of a force of special agents organized by Attorney General Charles J. Bonaparte in 1908, has used its present name since 1935 and is headquartered in Washington, D.C.Open the full entry and that close to 37 countries were purchasers of its software.⁠[26]

Delta’s article states that he had worked at Silent Circle’s office in Geneva, that when it closed he lost his work visa and had to choose between returning to the United States and coming to Delft, and that he applied for a position at Delft University of Technology; from 2016 he taught cryptography in the university’s Master Cyber Security program.⁠[3]

In the Delta interview he said that he chose the Netherlands because courses are taught in English, because his high-school German helps with some Dutch, and because he likes Europe’s international outlook; the article states that he had visited 46 countries and had decided to stay before Donald TrumpDonald TrumpDonald Trump (born 1946) is an American politician and businessman, a Republican who ran the real estate company the Trump Organization and starred in the television series The Apprentice. He served as the 45th president of the United States from 2017 to 2021 and has been the 47th president since 2025.Open the full entry’s election, which strengthened that decision.⁠[3]

On May 19, 2016, the Université libre de Bruxelles, its Polytechnic School and its Faculty of Sciences conferred an honorary doctorate on him as a campaigner for nuclear disarmament, human rights, individual liberties and privacy and the responsible use of technology, calling him “un des innovateurs les plus importants d’Internet” (one of the most important innovators of the Internet); the brochure states that for about ten years he had worked on practical ways to secure mobile communications. The other honorary doctors that year were Ann Demeulemeester, Jaco Van Dormael, Marianne Bertrand, Patrick Pelloux and Dong Qiang.⁠[1]

In May 2017 he spoke at a cyber security symposium organized by the Delft students’ association W.I.S.V. ‘Christiaan Huygens.’ In the Delta interview published on May 13 he said that he had changed his mind about quantum computing the year before: “I never used to take quantum computing very seriously.” Of the Internet of Things he said: “It is going to be a disaster because computer programmers do not think enough about security.” He also said: “Governments use my stuff.” He said that he never saw his work as protest but as building something that everyone could use.⁠[3]

On June 6, 2021, he wrote the thirtieth-anniversary essay in The Hague, Netherlands, stating that he had wanted PGP to be used for human rights, especially where people needed protection from their own governments, but could not say so publicly during the investigation because it could have been used to prove intent.⁠[10]

In the essay he listed uses of PGP: in the Kosovo conflict it helped enable the safe evacuation of 8,000 civilians, human rights groups documenting war crimes in Guatemala used it to protect witnesses from military reprisals, and human rights workers in the Balkans and the political resistance in Burma in the 1990s used it; he wrote that Robert Morris Sr., retired from the NSA, had mentioned to him that the agency worried PGP’s source code would teach many people to build strong public-key software.⁠[10]

He wrote that three decades on, strong cryptography was everywhere, in browsers, VPNs, e-commerce and banking apps, IoT products, disk encryption, the Tor network and cryptocurrencies, and that OpenPGP implementations had resurged; but twenty years after, as he put it, “we all thought we won the Crypto Wars,” governments of liberal democracies including Australia, the UK and the US were trying to restrict end-to-end encryption, and he wrote: “We are going to need fresh troops.” He wrote that democracies were sliding toward populist autocracies and that pervasive surveillance makes political organizing nearly impossible, as he said is the case in China; he argued that Huawei’s 5G deployment across Europe gives China easy SIGINT opportunities, that end-to-end encryption is essential to European national security, and he called for a hard push in policy to encourage its ubiquitous adoption.⁠[10]

As of November 2026 his website describes him as Associate Professor Emeritus of cybersecurity at the Faculty of Electrical Engineering, Mathematics and Computer Science of Delft University of Technology, and as providing cryptography consulting; its speaker page lists his topics as cryptography, privacy, authentication, surveillance technology, biometrics and post-quantum algorithms, along with the history of the crypto revolution and the legal battles over PGP, and states that most of his talks use no slides or notes, that he does not speak for a company and that he earns part of his living as a speaker.⁠[2][15][27]

The Blockworks article writes that, speaking with Pete Rizzo, host of Supply Shock, he said he knew Hal Finney was exploring proof-of-work projects and found BitcoinBitcoinBitcoin (common symbol BTC) is an open peer-to-peer electronic cash protocol, network, and native digital asset. Full nodes independently verify transactions and blocks according to the consensus rules; transactions are recorded as UTXOs, and blocks are organized into a public ledger through proof of work. Bitcoin is not issued or managed by any single institution, but using, holding in custody, and trading it still involve key, privacy, market, and legal risks.Open the full entry technically intriguing, but was busy with other work and did not become as deeply involved in early Bitcoin development as Finney did; he called Bitcoin “a very creative breakthrough in the development of digital money” and said: “For the first time, you actually had a feasible electronic money scheme that was decentralized.”⁠[16]

He said that holding bitcoin keeps assets “out of reach of the autocrat,” and mentioned the many people he had met at the Bitcoin conference in Argentina who described protecting their assets with it. The Blockworks article describes his relationship with Bitcoin as complicated, like his feelings about PGP; he said that he knew for a fact that PGP was in Al-Qaeda training manuals, but that it was also saving lives in wartime conditions; and he said: “I would like to see more examples of Bitcoin being used for good.” The Blockworks article also states that he appeared on stage with Adam BackAdam BackAdam Back is a British cryptographer and computer scientist, the inventor of the proof-of-work system Hashcash, and a co-founder and the chief executive of the Bitcoin technology company Blockstream.Open the full entry at the Plan ₿ Forum in Lugano, Switzerland.⁠[16]

Bitcoin Magazine published an article by Giulio Prisco on September 8, 2015, that lists him among the cypherpunks who wanted to make society better by writing code; it states that Adam Back tells the story of Hashcash, PGP, David ChaumDavid ChaumDavid Chaum is a cryptographer who introduced mix networks, blind signatures and the electronic cash system eCash, initiated the International Association for Cryptologic Research (IACR) and founded DigiCash in Amsterdam; he later developed voter-verifiable voting systems and leads the blockchain project xx network.Open the full entry’s DigiCashDigiCashDigiCash was an electronic cash company founded in Amsterdam by the cryptographer David Chaum. It developed eCash, a payment system that used blind signatures to protect payers’ privacy, and licensed it to banks in several countries for trials; it moved its headquarters to Silicon Valley in 1997, filed for bankruptcy protection in November 1998, and its software and patents later passed to eCash Technologies.Open the full entry and Stefan Brands’s electronic cash system, a history leading to Satoshi NakamotoSatoshi NakamotoSatoshi Nakamoto is the pseudonymous creator of Bitcoin, who published the Bitcoin white paper in 2008, released the first Bitcoin software and launched the blockchain in 2009, and stopped public activity around 2011; the person’s true identity has never been confirmed.Open the full entry’s Bitcoin white paper.⁠[28]

His website lists that he served on the Roundtable on Scientific Communication and National Security, a collaboration of the National Research Council and the Center for Strategic and International Studies, on the board of directors of Computer Professionals for Social Responsibility, and on the advisory boards of Santa Clara University’s Computer Engineering Department, AllClearID and AET Europe; he is a member of the International Association for Cryptologic Research and has been a Fellow at Stanford Law SchoolStanford Law SchoolStanford Law School is Stanford University’s law school. Its law curriculum began in 1893, and it offers JD and advanced law degrees. Its alumni include technology-media entrepreneur Michael Arrington.Open the full entry’s Center for Internet and Society.⁠[15][2]

His profile on the website of the elevate Festival (Graz, Austria, September 2005) states that he was a member of the Association for Computing Machinery and the League for Programming Freedom, chairman of the OpenPGP Alliance, and a member of the advisory boards of Anonymizer.com, Hush Communications, Encentuate and Qualys.⁠[17]

In 1994 Information Week named PGP one of the Top 10 Most Important Products of the year. In 1995 he received the Electronic Frontier Foundation’s Pioneer Award and the Chrysler Award for Innovation in Design and was named one of Newsweek’s “Net 50”; in 1996 he received the Norbert Wiener Award of Computer Professionals for Social Responsibility, a PC Week IT Excellence Award and Network Computing’s Well-Connected Award for “Best Security Product”; in 1998 a Lifetime Achievement Award from Secure Computing Magazine; in 1999 the Louis Brandeis Award from Privacy International; in 2000 he was named one of InfoWorldInfoWorldInfoWorld is a technology publication originating in 1978, serving enterprise developers, software architects and technology decision-makers as part of Foundry.Open the full entry’s Top 10 Innovators in E-business; in 2001 he entered the CRN Industry Hall of Fame; and in 2003 the Heinz Nixdorf MuseumsForum Wall of Fame.⁠[15][17]

In 2006 eWeek ranked PGP ninth among its “25 Most Influential Products” introduced since 1981; in 2008 PC WorldPCWorldPCWorld is a PC and consumer-technology publication launched in 1983, providing news, reviews and practical guides within Foundry’s media portfolio.Open the full entry named him one of the “Top 50 Tech Visionaries” of the last 50 years; in 2012 he was in the inaugural class of the Internet Society’s Internet Hall of Fame, together with, as Shachtman’s article states, Vint CerfVint CerfVint Cerf (born 1943) is an American computer scientist who co-designed the TCP/IP protocols and the basic architecture of the Internet with Bob Kahn and is widely known as one of the “Fathers of the Internet”; he worked at Stanford University, DARPA, MCI and the Corporation for National Research Initiatives, and was vice president and Chief Internet Evangelist at Google from 2005 to 2026.Open the full entry, Bob KahnBob KahnBob Kahn (Robert E. Kahn, born 1938) is an American electrical engineer and computer scientist who, with Vint Cerf, invented TCP/IP, the Internet’s fundamental protocols, and is regarded as one of the founders of the Internet. He led the system design of the ARPANET at Bolt Beranek and Newman, originated DARPA’s Internet Program and headed its Information Processing Techniques Office, and later founded the nonprofit Corporation for National Research Initiatives (CNRI), where he developed the Digital Object Architecture; his honors include the Turing Award, the Presidential Medal of Freedom and the IEEE Medal of Honor.Open the full entry, Charles Herzfeld and Tim Berners-Lee; in 2014 Foreign Policy named him one of its “Leading Global Thinkers”; in 2015 he received the EPIC Privacy Champions Award of the Electronic Privacy Information Center; and in 2018 he was inducted into the ISSA Hall of Fame.⁠[15][5]

The essays collected on his website include his author’s preface to PGP Source Code and Internals (MIT Press, 1995); “Beware of Snake Oil,” updated in 1997; “Why I Wrote PGP,” updated in 1999; his Senate testimony of June 1996; “No Regrets About Developing PGP”; the tenth-anniversary (June 5, 2001) and thirtieth-anniversary (June 6, 2021) essays; “The Evolution of PGP’s Web of Trust,” a chapter of Beautiful Security (O’Reilly, 2009); and John Perry Barlow’s foreword to The Official PGP User’s Guide, published in 1995.⁠[29]

“Why I Wrote PGP,” dated June 1991 and signed from Boulder, Colorado, was part of the original PGP User’s Guide and was updated in 1999. It says, “If privacy is outlawed, only outlaws will have privacy,” and argues that the only way to hold the line on privacy in the information age is strong cryptography. It recounts the Clipper chip announced by the Bill Clinton administration in April 1993, with a classified NSA algorithm and a government-held escrow copy of each chip’s key; the Communications Assistance for Law Enforcement Act of 1994, which required phone companies to install remote wiretapping ports in digital switches; and the wiretap-capacity plan disclosed by the Federal Bureau of Investigation a year later and defeated in Congress.⁠[7]

Personal website: https://philzimmermann.com/ (opens in a new window).⁠[2]

Silent Circle: Official website: https://www.silentcircle.com/ (opens in a new window).⁠[23]