In November 1952, a Harvard sophomore, Peter G. Neumann, had a two-hour breakfast with Albert Einstein, in which they discussed the physicist’s philosophy that “Everything should be made as simple as possible, but no simpler.”
Einstein’s aphorism led to a lifelong romance with both the beauty and the perils of complexity for Dr. Neumann, who went on to become one of the nation’s leading computer security researchers.
Dr. Neumann died on Sunday at the Santa Clara Medical Center in Santa Clara, Calif. He was still working full time on a Pentagon-supported advanced computer security design, which is being adopted by companies such as Google and Microsoft. He was 93.
The cause of death was complications from a recent fall, his daughter, Helen Neumann, said.
Dr. Neumann (pronounced NOY-man), who has worked as a computer scientist and security researcher at SRI International in Menlo Park, Calif., since 1971, has long been a voice in the wilderness warning about a computer industry that has been prone to repeatedly make the same mistakes.
In 2010, Mr. Neumann launched a research project that investigated how to protect against the most common types of security vulnerabilities. Funded by the Defense Advanced Research Projects Agency, or Darpa, the program, known as Cheri, developed a new approach to computer hardware that restricts software programs so that malicious instructions are impossible to execute.
An analogy would be replacing a master key that opens every door in a building with a set of keys that each only open the specific rooms their holder is authorized to enter — and making it physically impossible to copy or modify them.
Recently an industry organization known as the CHERI Alliance has begun to commercialize the design for consumer products and industrial applications.
“Peter Neumann is both one of the last of the old guard and a pointer to the future,” said Whitfield Diffie, a mathematician and cryptographer who is the co-inventor of public key cryptography. “He describes himself as having had a 70-year career in computer science, starting with his graduation from Harvard, and he has always advocated starting with hardware designed to support security.”
Beginning in 1985, Dr. Neumann served as editor for the Association for Computing Machinery Risks Forum newsgroup, an influential collection of emails from readers reporting computer failures and foibles that has an avid following of hundreds of thousands.
Since then, he has maintained the sprawling compendium of computer failures, flaws, foibles and privacy issues, annotating each of the 3,195 issues with wry comments and the occasional pun. In 1995, the list became the basis for his book, “Computer-Related Risks.”
In the 1990s, he was a key researcher on a Darpa-funded research project to develop new ways to detect intruders in large computer networks. Known as Emerald, the project did not lead to a successful commercial spinoff, but SRI won several lawsuits against Silicon Valley companies for using the technology without a license.
Despite his influence in the computer security world, Dr. Neumann preferred to maintain a low profile.
“There’s no limit on the impact that a small team can have if they don’t care who gets credit,” said Patrick Lincoln, the office director of Darpa’s Information Innovation Office, who described Dr. Neumann as routinely working behind the scenes without credit. “The world is just so much a better place for having had Peter.”
Dr. Neumann had been a frequent critic of the lax attitudes the industry has maintained toward both computer security and individual digital privacy.
“I’m fundamentally an optimist with regard to what we can do with research,” he said. “I’m fundamentally a pessimist with respect to what corporations who are fundamentally beholden to their stockholders do, because they’re always working on short-term appearance.”
Peter Gabriel Neumann was born on Sept. 21, 1932, in Manhattan. His father was Israel Ber Neumann, a noted art dealer, working first in Germany and then in New York, where he opened the New Art Circle gallery after moving to the United States in 1923. Dr. Neumann’s father fled to America shortly after finding himself seated near Adolf Hitler in a German restaurant.
His mother, Elsa Schmid Neumann, was a mosaic artist. Dr. Neumann’s two-hour breakfast with Einstein took place because his mother had been commissioned to create a colorful mosaic of Einstein and had become friendly with him. The mosaic was displayed for many years in a reference reading room in the main library at Boston University.
Dr. Neumann grew up in the Greenwich Village neighborhood of Manhattan before his family moved to Rye, N.Y., where he attended high school. He took his first computing job over a summer when he was in college, which involved programming an IBM card-punched calculator for the U.S. Naval Ordnance Laboratory.
He entered Harvard in 1950 and became one of the first computer hackers during his senior year. The term originally described people who were fascinated by the machines, rather than the later meaning referring to those who broke into computer networks.
At Harvard, he was one of the first programmers to have solo access to his own “personal” computer — at least, on weekends. He had the run of a computer known as the Mark IV. The Mark IV was one of the world’s first stored-program computers, and in 1954 Dr. Neumann earned the trust of its designer, Howard Aiken. Every Friday at 5 p.m., he would take over the care of the machine from its regular operators. He would have the run of the system for the weekend and wouldn’t leave until Monday morning.
“I was the operator, maintainer and guru,” he said. With another student, Fredrick P. Brooks Jr., who would go on to become an IBM computer designer, Dr. Neumann wrote a paper on using the Mark IV to compose music.
After spending two years in Germany on a Fulbright fellowship, Dr. Neumann received his Ph.D. in mathematics from Harvard and joined Bell Laboratories in 1960. He spent a decade there and became a key developer of the Multics operating system, an early Pentagon-financed project that was the first systematic attempt to grapple with how to share computer resources securely among many users.
Multics (Multiplexed Information and Computing Service) was developed collaboratively by researchers at the Massachusetts Institute of Technology, Bell Laboratories and the Honeywell Corporation beginning in the mid-1960s. The project pioneered concepts that became foundational to modern computing.
Dr. Neumann retained a lifelong passion for music, playing a variety of instruments, including the bassoon, French horn, trombone and piano, in a number of musical groups. At computer conferences, he frequently led his colleagues in Gilbert and Sullivan songs.
In December 2024, Dr. Neumann made an anonymous $4 million donation to the San Francisco Symphony to save its chorus, his daughter, Helen, said.
She is his only survivor. He was married twice. His first marriage, to Anne Ferris Rittershofer, ended in divorce. His second wife, Elizabeth Susan Neumann, died in 2020. Two sons, John and Christopher, predeceased him.
Dr. Neumann had occupied the same office at SRI International since arriving as a computer researcher in 1971. Until the building was modified to make it earthquake-resistant, the office had attained notoriety for the towering stacks of computer science literature that filled every cranny.
Legend has it that colleagues who visited the office after a 1989 earthquake were stunned to discover that while other offices were in disarray from the 7.1-magnitude quake, nothing in Dr. Neumann’s office appeared to have been disturbed.
