Q&A: RSA crypto pioneer Adleman keeps pushing the limits

Dr. Leonard Adleman tells InfoWorld all about RSA's big breakthrough, why DNA works great for computing, and our coming cyberwar risk

Q&A: RSA crypto pioneer Adleman keeps pushing the limits
Peter Sayer

I recently had the pleasure of interviewing Dr. Leonard Adleman -- the “A” in the very popular public cryptographic algorithm RSA -- as part of the Association for Computing Machinery’s 50th anniversary celebration of the Turing Award. In 2002, Adleman himself won the Turing Award, often referred to at the Nobel Prize of the computing world.

Like many of his Turing Award-winning peers, Adleman is still actively involved in solving some of today’s most important computer and security problems. His love of math and number theory, combined with his interest in molecular biology, created a whole new way of thinking about computing that blurs the lines between silicon and life. If we ever see bio-robots that think and act like humans, Dr. Adleman will be one of the people you should thank.

I asked Dr. Adleman about his contributions to the creation of the RSA algorithm back in 1977. I knew that Whitfield Diffie, Martin Hellman, and Ralph Merkle had first worked out public key crypto the previous year, but hadn’t quite figured out how to use large prime numbers -- and the difficulty of factoring them eventually took over the world. Adleman had this to say:

I was the number theorist in residence. Ron [Rivest] and Adi [Shamir] were really more interested in public crypto than I was initially. I was more interested in math and number theory at the time, and at first I couldn’t see how great a role crypto would play in our lives in the future. But as Ron and Adi came to understand that solving their problems would probably involve algorithmic number theory, I got involved.
Basically, Ron and Adi would propose many different solutions [42 to be exact], and I would quickly shoot them down. They would make many attempts over the months, and I would run into them at birthday parties and celebrations and find flaws. One night, at a Passover dinner, Ron drank a lot of wine. After dinner, around midnight, Ron called me and told me about the large prime number and factoring idea that would eventually become RSA. And right on the phone I said, “Congratulations, you’ve done it!” I knew we couldn’t prove it was unbreakable, but I couldn’t see any flaws.

The RSA guys went on to form a company and popularize public cryptography.

Dr. Adleman’s interest in molecular biology, especially the HIV virus, also bore fruit. In 1983, one of Adleman’s students, Frederick Cohen, created the first (or one of the earliest) self-replicating programs, which copied itself to other programs to spread. Adleman saw the similarities between his biological work on HIV and what Cohen was doing, and he called Cohen’s creation a computer “virus.” Cohen credited Adleman with creating the name in his 1984 paper, “Experiments with Computer Viruses.”

Computing with DNA

A decade later, in 1994, Dr. Adleman introduced the world to DNA computing in his seminal paper, “Molecular Computation of Solutions to Combinatorial Problems.” I remember reading the news stories surrounding his announcement with a mix of astonishment and incredulity. If it had been announced this year, I’d still probably be checking to see if it was fake news. But it wasn’t and isn’t. Someone had figured out how for the first time to use biological life to compute.

I asked Dr. Adleman how the concept of using DNA to compute came to him. He replied:

It came to me because of my interest in theoretical computer science and HIV. My interest in HIV led me to ask a colleague if I could get into his lab to become more proficient in professional molecular biology. There I saw the world of DNA. It was like being in Disney World! Since I had read Alan Turing’s 1936 paper, “On Computable Numbers, with an Application to the Entscheidungsproblem,” I knew that computing was easy, that the basic components were all around us.
All you had to do was find a way of storing information and a way of doing simple operations on it. I realized that DNA was a magnificent way of storing information and that living things had created enzymes to manipulate that information. So I knew DNA computing would work. Life and computation are not very different from one another after all. Maybe we can’t put silicon computers into human cells, but we might be able to put DNA computers into them.
One of the best parts of my discovery is what my students and others have done with it. They have started to make structures out of DNA. It even has a name: DNA origami. They have even made DNA smiley faces. If you need 50 billion statues of yourself, they can build them out of DNA.


I asked Dr. Adleman what concerned him the most about computer security. He acknowledged what he was about to say might sound a bit apocalyptic:

It’s not any immediate problem. There are a zillion immediate problems, and a whole industry trying to respond to those. But I hope security experts will take a longer view. What I’ve thought about, worried about, and am actually writing a book about is the “compuverse,” its extremely rapid evolution, and its potential for catastrophe.
For example, we are all aware that it is an easy thing to attack an internet site. But the major powers, and perhaps others, are almost surely working to acquire the ability to take down an entire nation’s computation power for a prolonged period of time. A first-world country with no computational infrastructure is a country with no economy, no food, no power, and ultimately not a country at all. In the not too distant future, cyberweapons may become weapons of mass destruction. Computer security experts might be able to prepare for or prevent that from happening.
To end on a slightly more positive note, there may be a small silver lining to our difficulties protecting computer systems. Suppose some leader decides to hit “the button” to launch nuclear weapons. There are lot of computations between that button and the weapons. In today’s world, can the leader still be sure that what he thinks will happen will?

Currently, Adleman is working a new approach to complex analysis called strata and writing a book on memes. That’s in addition to his day job as a computer science professor at the University of Southern California. It’s great to see one of the earliest contributors to computers and networks as we know them still going strong and contributing important insights to problems we face today.

Copyright © 2017 IDG Communications, Inc.

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