The HLF Portraits: Martin Hellman
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The HLF Portraits9 / 66
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00:00
Video gameComputer scienceMathematicsWave packetSensitivity analysisIntegrated development environmentFlow separationLine (geometry)Universe (mathematics)Extension (kinesiology)MereologyPhysicalismNumberGoodness of fitFamilyPublic-key cryptographyPressureNeighbourhood (graph theory)Absolute valueInheritance (object-oriented programming)GradientStudent's t-testData miningSelectivity (electronic)Block (periodic table)Electronic program guideMultiplication sign2 (number)Meeting/Interview
08:24
Video gameMathematicsGame theoryComputer programmingElectric generatorUniverse (mathematics)Structural loadMereologyPhysicalismElementary arithmeticResultantHypothesisInternetworkingProcess (computing)Connectivity (graph theory)Information securityPoint (geometry)Inheritance (object-oriented programming)Control flowGradientSpring (hydrology)Direction (geometry)Sound effectNeuroinformatikTransmissionskoeffizientDegree (graph theory)Multiplication sign2 (number)Office suiteMeeting/Interview
16:48
Flow separationCalculusMereologyResultantHypothesisGoodness of fitMeeting/Interview
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MathematicsTheory of relativityStatisticsSemiconductor memoryFinitismusHypothesisSystem callPoint (geometry)Spring (hydrology)Different (Kate Ryan album)2 (number)Meeting/Interview
19:48
CodeVideo gameInformationInformationstheorieCryptographyComputer programmingFehlererkennungGroup actionTheoryPhysical systemTerm (mathematics)GodCryptosystemBranch (computer science)Error messageMetropolitan area networkPoint (geometry)HorizonGreedy algorithmEncryptionInteractive televisionDatabase normalizationEvent horizonAuthorizationNeuroinformatikSingle-precision floating-point formatLengthMultiplication signDifferenz <Mathematik>Message passing2 (number)Meeting/Interview
25:34
Video gameInformationInformationstheorieCryptographyData compressionType theoryElectric generatorSurvival analysisCausalityBayes' theoremForcing (mathematics)MereologyAreaRevision controlFamilyPublic-key cryptographyParameter (computer programming)Process (computing)MathematicianMetropolitan area networkFood energyPersonal digital assistantPoint (geometry)Online helpInteractive televisionObservational studyTraffic reportingInformation privacyMultiplication signRight angleBell and HowellSoftware developerMeeting/Interview
34:43
AlgorithmVideo gameSequenceInformationCryptographyMathematicsMicroprocessorVideoconferencingEquivalence relationBitConnected spaceFormal grammarGroup actionLimit (category theory)ChainMereologyPhysical systemNumberSystem callRevision controlSimilarity (geometry)CryptosystemPublic-key cryptographyCASE <Informatik>Process (computing)Point (geometry)Control flowEncryptionCivil engineeringData conversionObservational studyLattice (order)View (database)Key (cryptography)Context awarenessMultiplication signMessage passing2 (number)Right angleOffice suiteDesign by contractSoftware developerMeeting/Interview
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AlgorithmInformationstheorieCryptographyLibrary (computing)DigitizingCategory of beingFlow separationEquivalence relationProof theoryForm (programming)BitContent (media)MereologyProjective planeTerm (mathematics)Database transactionNumberPublic-key cryptographyText editorRemote procedure callElectronic signatureInformation securitySchlüsselverteilungOcean currentAuthenticationWordStudent's t-testSign (mathematics)Information privacyKey (cryptography)Right anglePosition operatorMeeting/Interview
52:26
Touch typingPerspective (visual)Rational numberShift operatorSoftware testingProbability density functionLine (geometry)Group actionMereologyMoment (mathematics)Projective planeResultantDatabase transactionDevice driverGoodness of fitPlanningProcess (computing)Point (geometry)TelebankingWordEncryptionGreatest elementTexture mappingDifferent (Kate Ryan album)ArmLengthMultiplication signFreewareRight angleWeb 2.0Meeting/Interview
01:01:00
8 (number)Bit rateInternet forumComputer animation
Transcript: English(auto-generated)
00:17
I'd like to begin at the beginning with your childhood.
00:21
Where did it happen? What was the life of your family, particularly the intellectual life of your family? It starts in Beth Israel Hospital, October 2, 1945, and my mother in fact told me. I was the second of three boys and she said I was born in a hurry and I've been
00:43
in a hurry ever since. She didn't give birth in the cab, fortunately, but an intern delivered me because the doctor couldn't get there in time. My father was in the South Pacific, fortunately on Hawaii instead of Okinawa.
01:01
As I say that, it's something I've gone back in the personal work I've done. I'd never really thought about what it was like for my mother to be left with a two and a half year old and three months pregnant with me and have a husband get on a troop train. As I really started to think about that, not knowing where he was going, it really
01:23
hit me. That's where it started. My father was a high school physics teacher. When I was born, he was in the Army, Signal Corps, but he came back. That was his career for his whole life. Physics was throughout the family. His younger brother by two years taught at Bronx High School of Science where I went and
01:44
in fact was my physics teacher. Interesting story, which I'll leave out for now. And there were books, but it's interesting. There wasn't pressure to, there wasn't the whole thing we have today. Like I didn't learn to read till I was in first grade. I mean, that was standard.
02:01
But I remember my father had Gano's physics, 1898 or something, copyright. And I would look in there and I knew at an early age I had to be a scientist. Do you want that story? Yes, absolutely. I'm in third grade. We're doing, studying the explorers.
02:21
This is New York, so we're studying like Henry Hudson and people like that. And I desperately wanted to be an explorer, but I knew that I had to be a scientist. I don't know how I knew, but I knew the idea of being an engineer or a computer scientist didn't exist in my mind. And, but my wife has pointed out, interestingly,
02:42
Dorothy, that I did become an explorer. Both in my technical work, like public key cryptography, the award which gave rise to this interview. I went places where no one else went. In fact, where people told me not to go. And then in my personal life, the same thing. Although my wife was my guide on that one.
03:02
We'll get there. We'll get there. But I still want the child. The child. What is the child reading? Oh, but there's another thing about the child. Yes.
03:22
He felt friendless at age seven. I mean, when I was a little kid, up through age four and a half, we lived in a neighborhood that was 99% Jewish. The Bronx, where I grew up, was totally Balkanized along ethnic lines. But when I was four and a half, St. Patrick's Day 1950,
03:41
we moved to the West Bronx. My parents bought a house, a two-family house. And they never would have moved to an Irish Catholic neighborhood in those days and in that environment. But all the kids my age on the block were Irish Catholic. And so I felt ostracized. I mean, all kids are ostracized to some extent.
04:01
But for me, I was a Christ killer. I was a dirty Jew. I mean, I played with the kids, too. But every once in a while, that would come out. But even when I went to the public school, because all the Catholic kids went to the parochial school, but even when I went to public school, which was almost entirely
04:22
Jewish, even there, after a while, I was awed. And I felt friendless. What was awed about you? I think I was probably sensitive. I also think I really was always drawn to the feminine side of life.
04:42
When the other boys would steal the girl, you know, at recess, the other boys would steal the girl's ball and keep it away from them and taunt them. I would try to help the girls get it back, which, of course, endeared me to the other little boys. No wonder I was friendless. But I always loved girls. And this was pre-sexual, obviously, I mean, at age seven or eight.
05:02
There was just something about them that I was drawn to. And still, I'm drawn to the feminine side. Maybe empathy is one of the elements? I think empathy is part of it. And having grown up being ostracized,
05:21
relationship is really important to me. And in fact, it's been interesting. Dorothy pointed out, and I also realized, that the friendless kid has grown up to have a huge number of friends. And people talk about how friendly I am. I mean, it's, but I think it's because I had to learn how to make friends. How much of the ostracization might have been also
05:42
that you were what's now called a nerd? Or I'm guessing that, that somebody very interested in reading, somebody very interested in maybe scientific issues? Probably some of that. Revenge of the nerds, here I am. It's probably some of that.
06:00
And I don't know, it was actually a gift. I mean, at the time, I would have given anything to be popular, to be like the other kids. But I look at it now, who'd want to be like everybody else? Especially when being so different has taken me such interesting places, both professionally and in my relationship with my wife, and the work I do.
06:24
Sometimes, I'm not saying it happened in your case, there's a teacher who either protects or inspires along the way. Did you have any of that, either in the younger age or later on in high school?
06:40
Mentors, people, adults whom you could communicate with? Well, teachers always liked me. I mean, I was a good kid, and I was somewhat of a teacher's pet, which probably was another reason that I felt friendless. I was interested in following the rules, and so certainly, I remember my teachers
07:00
in fourth grade, Mrs. Donovan. I was actually fourth and fifth grade, not so much sixth. At junior high school, there was Miss Blake, my math teacher really took me under her wing. And my uncle, when he taught physics, helped me with some things and took a real interest.
07:24
He died recently at age 106, just months ago. I loved it, because he taught, he had several Nobel laureates in physics, having taught at Bronx Science, but he always called me his best physics student.
07:40
Now, I'm not saying that was true, but I loved that he said that, and that's how I knew that he was still cogent about six or nine months ago when I called him. And he said, oh, my best student ever. And I knew that he knew who I was, because he doesn't always know. Now, when you got to Bronx Science,
08:01
which is itself a selective universe of nerds, it's an overused word, but people interested in science, were you less friendless? I mean, was that finally beginning to find colleagues with whom you could share ideas? Yeah, and actually, looking back, even in elementary school, I wasn't friendless. Tom Burson, who's a good friend of mine now,
08:23
it's really funny, we're both married to Dorothy's, which is an unusual name for our generation. He is prominent in cybersecurity. He was the first fellow of the IACR, the Cryptologic Research Association. He was a friend of mine, starting in fourth grade.
08:41
I had other friends too, so maybe I was just overly hard on myself. But every step, I went to junior high school, and there were new kids. I mean, some of the old kids came with me, but new kids came in too, and I could lose some of the, what I felt, rightly or wrongly, was the taint of being Marty Hellman
09:01
from elementary school and high school even more. But the real change was in college, when I went to NYU, which is an interesting story. I would have gone to City College, because in New York in those days, City College was free, and college within the Jewish immigrant culture
09:23
that I grew up in, even though my parents were born here, because they stayed in the Bronx instead of moving to the suburbs, like most of my aunts and uncles. And my father, there wasn't a lot of money with my father being a teacher. College was not about the parties and football games.
09:40
It was about getting an education so you could get ahead. My father went to City College, his younger brother, my uncle, who taught me physics, went to City College. Almost all my aunts and uncles went to one of the City Colleges, and I would have gone there too, except NYU offered me a full tuition scholarship, and I could walk to NYU from my home,
10:00
and so I saved 30 cents car fare every day. Of these things, life directions are made. And college, the thing that really changed there was I had my first serious girlfriend, and she was really popular.
10:20
She was a sophomore, she was two and a half years older than me, and she ran for, it was called the University Heights Campus, which NYU no longer owns. She was one of the four contestants for Miss Heights, and this is not how I thought of myself, and she picked me out.
10:42
I mean, it was really funny. I mean, what's she doing with me? But it helped change my self-image, which had been changing all along, but that was really key. But looking back, like I was talking to one of the girls, obviously now women, who I went to junior high and high school with,
11:01
and it's funny, she remembers me. I took her sailing, we had a small sailboat in spite of the lack of money, which was interesting. I took her sailing out on Long Island Sound, and when I was talking with her and going over things like this, she says, oh no, the way she remembered me is on the boat,
11:21
as I put it, she didn't use these exact words, but heroic pose number three, on the front of the boat, getting ready to- You were a young man after all. Oh, yeah, I was probably 17 at the time, something like that. What was your major at NYU? Oh, all my degrees are in electrical engineering. When did that notion, this is what I want to do, begin?
11:43
Let's see, I switched from physics to electrical engineering probably my junior, senior year of high school. I became a ham radio operator. You know, it was either stereo or ham radio in those days that got people into these things. Now it's more computers. And that's when I,
12:00
that whole idea opened up to me, and I really loved electrical engineering. Where does that take you? You're thinking about a career, presumably, by the time you're at NYU in electrical engineering. What were you expecting of your career? Of course, many things happened to it, but what are you expecting?
12:20
Well, it's a good question. It reminds me, I remember sitting in probably my junior or senior year of college, and I'm in some class, I'm looking at like 40 other students, all gonna be electrical engineers. And I know this is just one of many universities and colleges across the country, across the world. And I wonder, what are all these people gonna do when they get out? Because the only thing I could think of electrical engineers doing at that point
12:42
was designing transmitters and receivers, which is what I did as a ham radio operator. And I never thought of things like public cryptography, the internet didn't exist. I also didn't think of like the summer jobs I had. One of them was in microwave plumbing,
13:03
1965, before my senior year of college, I worked out at this place that was building components for phased array radars, which were being used to track missiles. Never thought of stuff like that. I mean, I fit very close to the stuff
13:20
that I worked on as a ham. And then the next year, I just, between my undergraduate and starting at Stanford, I worked for Aerospace Corporation in LA, El Segundo. And there I was making gallium arsenide diodes for mapping sunspot activity,
13:42
which whoever thought of that. But the really interesting one is the summer after that, the summer of 1967. I got a job at TRW Systems, and I think I might have known it was in the weapons systems effectiveness department, but I don't even think I knew that. And of course, it's all classified work.
14:01
When I get there, I find out I'm flying warheads in on the Soviet Union on a computer to try to maximize our effectiveness, effect of being able to kill people if a nuclear war comes about. It bothered me a little bit, but I did the work. My office mate and I used to joke if we had a good idea,
14:21
it might result in another 10 mega deaths, which was bowing ourselves out of proportion. I mean, we were working on just such a little, we were just small cogs in this thing. And I've used that in some talks I've given. Now that I work on trying to avoid nuclear war, I sometimes start out by saying, I wasn't always talking this way.
14:42
In fact, in the summer of 1967, I was flying warheads in on the Soviet Union as part of our MIRVing effort. And what I say is, I couldn't see a better way to improve our national security than I can now. Before we get there, we need to develop your scientific
15:04
and intellectual capabilities. You go to Stanford, and by my lights, burn your way through Stanford. I mean, you're in one year, you've got a master's. In two more years, you've got your PhD. Actually, one year. Okay, technically it took me two years more
15:22
to get my PhD, because you had to have two years. But I left after one year and did research at IBM. That's a neat little story. In my second year of graduate studies, so the first year I'm really working on research at any level, I'm still taking three courses,
15:41
which for many people would be a full-time load, and for me was a three-quarter load. So I'm only working one quarter time on my research. But I start to wonder, and this is actually a really helpful thing for young people working on their graduate work. Many of them have said how much it helped them. I started to wonder, who the hell am I
16:00
to think I can make an original contribution to knowledge, which is what you do for a PhD thesis. Maybe I should drop out of the program. My work's not going anywhere. As my mother said, I was in a hurry from the day I was born. I actually was contemplating, should I drop out of the program? And then spring break came,
16:21
so it was just about this time of year, 1967. And I thought, you know, I haven't really been able to work full-time on research. Let me take a week, Monday through Friday. I'll take the weekend off and rest up. But Monday, I'm gonna start at nine to five, I'm gonna work on research. Well, within the first half hour,
16:41
I had the key result that became the central part of my thesis. There was more we had to do. But in roughly half an hour, I went from thinking who am I to make, to think I can make an original contribution to knowledge, to having the most important part of the result. And I love this. I tried for another hour or two
17:01
to take it to the end, and I couldn't. And my thesis advisor was at a conference, so I couldn't talk to him. And this was before email, 1967. The Dark Ages. Yes. But rather than slave-driving myself, as I did later in life, and sometimes do now,
17:21
I gave myself the rest of the week off, because I felt that I'd done in that hour, half hour, hour and a half, I'd done a week's worth of work, and actually I'd done several years' worth of work. And so I took the rest of the week off and had a good time, apropos of pleasure.
17:40
And when my advisor came back, he agreed. I mean, he was excited too. And it took us a month, but it only took us a month because it was so simple to get from there to the end. We tried more complicated things, and it was a very simple approach that he actually came up with. It was calculus of variation, standard mathematical technique that took us from my important thing to the end.
18:03
So now here I am. It's spring 1967. I'm in my second year of graduate work, and I've taken the summer off, so I've only done three quarters and two or three quarters, depending where you're talking about it. And I'm basically done with my thesis. And so... Which, by the way, was formerly called...
18:22
Oh, this was Learning with Finite Memory. It was very different from cryptography, although it had to do with statistics and probability, so it's related. But we were married at that point for a little over a year, and plans keep changing. We weren't gonna have kids for five years, but a year into the marriage, we decide to have our first child,
18:41
and Dorothy's now pregnant. And I like money, especially didn't have much. I was living on, I don't know, $200 a month, I mean, which admittedly was more than today, a fellowship. So I go to Tom Covert, my advisor, and I say, you know, I just have enough coursework
19:02
to get the PhD. I don't have enough research units, but I've done the research. Could I go work at IBM Research? And you give me, you know, I won't be here, but you'll give me credit for doing the research I do there, and I can get paid money. And he said, fine. And advisors are not supposed to say fine. They're supposed to say no, don't distract yourself.
19:22
No, I was done, because I was done with the, no, I was done with the thesis. So it was fine, I mean, it was just, basically Stanford wanted more money. And so that was the other neat thing. I thought I'd pay that out of this huge salary that IBM was paying me, compared to the $200 a month I'd been living on. IBM was very generous, and they made me an IBM fellow,
19:41
that is, there are different kinds of IBM fellows, but this was a graduate fellowship, basically. At the Watson. At the Watson Research Center in New York, and they paid my tuition. And they even paid our obstetric bill. I mean, it was unbelievable. I don't think it works that way anymore.
20:01
So what was your question, did I answer it? Well. Oh, two years, one year. So I actually finished the PhD in two years, a little less, because I took a summer off. But I had to stay another six, I had to pay tuition for another six months to get research credits for another. So Stanford being greedy. Well, we gotta keep the system going.
20:24
Now, at the Watson, is it called lab? Watson Research Center. Watson Research Center. T.J. Watson Research Center. I'd like to know, because yours has been a very collegial life, friendless initially, but collegial certainly. But the friendless may have been in my imagination.
20:42
I understand, but certainly a collegial life. What is the collegial scientific life at the Watson Center at that point? How, are you locked in a separate room? Are you, is there discourse going on? What are people interested in finding out?
21:01
Well, there was a lot of interaction. But the most important, relative to my later career, was with a man named Horst Feistel, who had been hired roughly the same time I had. IBM was starting its research effort in cryptography. They could see the need on the horizon. And I think they were thinking primarily
21:21
in terms of time-shared computers, where many people are using the same computer, whereas prior to that, one person at a time would run on a computer. And how do we keep your program from reading my data and they wanted to encrypt it? And so they hired Feistel from MITRE Corporation in Massachusetts.
21:45
He was in the same department that I was. And I didn't work, I wasn't working on cryptography, but I would have lunch with him, I'd talk with him. And so that was one of the key things that got me interested in cryptography.
22:02
A, seeing that IBM was spending money on it, which meant that it reinforced my belief or maybe created the belief that there was a growing commercial need for encryption. And B, Feistel would describe to me some of the classical cryptographic systems. Like one of them, you take your message
22:21
written out in English, like attack at dawn. You then take the text of a book, like in the beginning, God created the heavens and the earth, and you add them together. You think of A as zero. So in the beginning, God created the heavens. Heavens has an A in it. So wherever the A is in heavens,
22:41
that gets added to whatever letter of attack at dawn is underneath it, and you just get that letter. If it had been a B above it, it would move it ahead one and so on. And it seems impossible to break that cipher without knowing what the book is, because then the person at the other end subtracts in the beginning, God created the heavens and the earth.
23:01
But Horst explained to me how it could be done. And it was very easy, and I'd studied information theory for my PhD, and it was really information theoretic, because it has to do with the fact that English is more than 50% redundant. Like you can leave the U, when you have a Q followed by a U in English, you could just leave the U off transmission,
23:22
and add it back in at the other end. And it turns out there's a lot more redundancy than that, and you can compress English by about four to one. And so this is a two to one compression, because you have your message, attack it on, and you have the book, which is the second message, being compressed into the length of just one of them.
23:41
But because it's two to one, it's at least two to one redundant, in theory it's potentially possible to break it, and in fact it is. Do you begin to think of yourself as in cryptology at this point? Not yet. Not yet. So there were three key events. Actually, that January while I was at IBM, I went to my first international symposium
24:02
on information theory, and the banquet speaker was David Kahn, the author of The Code Breakers, which at that point was a best-selling book of the history of cryptography. And that was one of the influences. Horst Feistel at IBM was the second. And the third key influence was the year after 1969,
24:23
after one year at Watson, IBM. I go to MIT and I'm an assistant professor in the information theory group. And Peter Elias, now deceased, was one of the original contributors to information theory. And he gives me a monograph.
24:42
It was a reprint of a paper that Claude Shannon, who was the father of information theory, had published in 1949 in the BSTJ, the Bell System Technical Journal, linking cryptography and information theory. And, oh, I'm an information theorist?
25:01
And that's when I realized cryptography is a branch of information theory, which had escaped me and most other information theorists. Information theory is concerned with coding information. Coding for compression, as I just described. Coding for error correction. So, like you might repeat each letter three times. Attack at dawn might become A-A-A-T-T-T.
25:23
So if there's a single error made, you can correct it. Like if A-A-A comes out A-C-A, you say, oh, that's probably an A. But there are much better ways of doing error correction. And then the third way that I had missed up to that point was coding for privacy
25:40
and authentication, which is cryptography. And it actually turns out that Shannon had worked on cryptography during World War II at Bell Labs. And that 1949 paper was a declassified version of a 1945 classified report. So his work on information theory,
26:01
which was published in 48, seems to give rise to the 1949 paper if you just look at the public dates. But when you look at the footnote and realize that the cryptography work occurred in 1945, and you see how similar it is to the information theory work, you realize that information theory probably owes its birth to Shannon's work in cryptography.
26:24
Now, are you at MIT? Is it MIT that you meet a fellow researcher who will become very important to the development of your thinking about cryptology? Whitfield Diffie? Yes. No. No. No, I didn't meet him until the fall of 1974.
26:41
So 1969 to 71, I'm an assistant professor at MIT. I come back here in 1971 as an assistant professor and then subsequently associate in full, and now emeritus, basically retired status. By the way, why did you leave MIT? Wasn't that paradise? Oh, God, no. Forgive me, MIT.
27:02
I really wanted to stay at Stanford, but my advisor said it's really important to go away for a few years. Stanford was concerned about inbreeding. It still is, but we sometimes hire our own PhDs because if you hire a Stanford PhD at Stanford,
27:22
he or she is largely replicating the thinking of their advisor and you want to get new ideas. And so it seemed at the time like I had to jump through this stupid hoop of three years in exile, as I joke about it, on the East Coast, IBM and MIT. But I was gonna come back and work with my advisor.
27:42
I really want to detain you for a second if it's possible to describe the intellectual climate at MIT, even if you intended to go back to Stanford anyway. But Stanford does become the gestation point of such phenomenal things. But what is happening at MIT? Is it collegial?
28:01
Are the questions being asked there interesting to you? Yeah, well, first of all, Peter Elias giving me, I mean, obviously there was interaction and collegiality. I mean, Peter, it wasn't like I asked about it, but maybe I mentioned Feistel or something, and Peter said, oh, that reminds me, here's this paper,
28:22
and he gave it to me. And Bob Gallagher was very helpful to me. Dave Forney, who had left MIT and was an industry but very closely associated. There was a lot of interaction. But it was the dream of California that drew you? Then I'm still not sure why you're not. Oh yeah, I remember, I grew up in the Bronx.
28:42
And so let's see, what drew me to California? Logically, I can point to things like I wanted to, I have several answers. I ran away from home. My mother, my brothers and I have joked, my mother was an amazing woman. And we have joked if she, in fact, Dorothy and I have said, if she'd been born a generation later,
29:01
she would have been running a billion dollar company. Instead, being born in 1914, she put all that energy into raising me and my two brothers, which made us wanna run away from home. And so that's one answer. Another, I was running away from the ethnic consciousness of the Bronx and California was much better that way.
29:23
The Beach Boys were singing about California girls, Mamas and Papas, California Dreaming. This is the 60s. We're the same generation, I totally understand that. So I was pulled, but I think at a more mystical level, and I'm a scientist and engineer, but I have a strong belief in forces
29:43
beyond our understanding and have more than a belief of conviction. I've experienced them in my own life. I had to meet Dorothy. I didn't know I had to meet Dorothy, but she's just been amazing.
30:02
She saved my life. She saved your life. Oh yeah. If it weren't for her, I'd still be doing cybersecurity or pretending to do it cause I'm 71. I mean, mathematicians are dead by the time they're in their mid thirties. There's some exceptions, but also people in academia want to work
30:23
on the really big problems like public key cryptography. Well, a bigger problem is there. What bigger issue is there than the survival of civilization? And I wouldn't be working on that if it hadn't been for her. And it's more than that. I mean, it helped me to shed the,
30:43
it more than helped. I couldn't stay married to Dorothy. In fact, we were headed for divorce 40 years ago because we want to situate you in this time. So why did I want to come back? I love California. I mean, it was all the things I said. It was not the Stanford intellectual culture.
31:01
I may be reaching. Oh, there's a story there. Okay. My junior year, my first technical job working on microwave plumbing, my old girlfriend, the first serious girlfriend that I talked about, she'd moved to San Francisco. And she mentioned there's this university down the peninsula. I'd never heard of Stanford in 1964. I mean, it was not known the way it is today.
31:24
And I figured because it's in California, it's gotta be laid back and easygoing. This was the picture I had in my mind. I mean, every part of California was on the coast, even Bakersfield, which it isn't. And I remember that summer job, I was carpooling with another man
31:41
and he wanted to go to Princeton for electrical engineering graduate studies. And I wanted to go to Stanford. And we were kind of commiserating how he was gonna be working hard at this Ivy League, you know, type A school, whereas I was gonna be basking in the California sun. Yeah, when I found, of course, the surf. Actually, I did windsurf here with a wetsuit,
32:01
but the bay is cold. But when I found out Stanford was a top school, I came anyway. So that's a funny story. So here you are. You're back in Stanford. What are your intentions at this point, intellectually? You've been converted in a way to cryptology?
32:22
Not yet. Not yet. No, so it kind of grew with time. So there was the Ellenville Conference in 16, I'm sorry, the Information Theory Symposium, which was in Ellenville, New York, 1969. There was Feistel at IBM, 69. I'm sorry, 68 to 69. I was at IBM. And then Peter Elias, MIT, 69 to 71.
32:43
I started playing with it. And it grew with time. And every time I'd go to a conference and people would say, what are you working on? I'd talk about data compression and other areas of information theory. And then I'd say, I'm also looking at cryptography. And my colleague's response, I believe was absolutely uniform,
33:00
which is, you're crazy to work on cryptography. And the answers tended to be the same. NSA, the National Security Agency, has a huge budget. We didn't know how big until Snowden's revelations. They've been working on it for decades. How can you ever hope to discover something they don't already know?
33:21
And if you do anything good, they'll classify it. These were the two arguments that were made. Why were you not smart enough to listen to them? Oh, why was I smart enough not to listen to them? Yes, really, in the end. Well, this is the Wisdom of Foolishness lecture that I love. I think getting beat up as a Christ-goer
33:40
had something to do with it. I mean, I wouldn't want to go back and live through that again. I wouldn't wish it on anybody else. But growing up, I wanted to be like the other kids, but I couldn't be like the other kids for many reasons. But let's just focus on the Jewish versus not Jewish part. In self-defense, I adopted the attitude of who would want to be like everybody else?
34:02
Well, me, of course. But it was a protective coating. But in time, I came to believe my own bullshit. When my colleagues said, you're crazy to do that, rather than chasing me away, if anything, it drew me.
34:20
Right, right. So you weren't crazy, it turns out, to do it. No, in fact, in the Wisdom of Foolishness talk, I could probably have a dozen or more colleagues who were told they were crazy to work on breakthrough technologies that they worked on. And in my Stanford Engineering Hero talk,
34:41
which is on YouTube, people can find it, just Google Hellman Stanford Engineering Hero. It's the Wisdom of Foolishness. Vince Cerf, who was key in development of the internet, says people thought, and I emailed each of these people, four or five of them, to make sure I got it right. He said, even after the success of the ARPANET,
35:01
which preceded the internet, people thought packet switching would not work. And for things like audio and video, and of course today, all your Netflix and Amazon Prime videos come over packet switching. Federico Faggin, who designed the first microprocessor at Intel, had a similar story.
35:20
So the wisdom of, not perversity, but foolishness. Foolishness. Seeming foolishness. Seeming foolishness. And actually, it's when you were talking about doing what you want to do. Who but a fool would do what they want to do instead of what they think they ought to do? And yet, this comes back to that mystical side of life
35:41
where we're pulled. I sometimes joke that there's a muse of cryptography or a muse of civilization surviving who whispers in our ears. And she picks? Oh no, she talks to everybody. She talks to everybody. She talks to everybody, but only a few fools listen to her. That's why she has to talk to so many people. Well, you listen. So how do we get you full-time into cryptology,
36:05
fighting the fools, challenging some of the current notions. And then fighting NSA. And then fighting NSA. How did that happen? That's in the 70s, the early 70s. Well, it started in 68 at IBM in 69.
36:20
And I'm starting to spend more time on it. And I get a small result, but publishable. And I realize, oh, maybe I can do this. I start spending more time, but I'm stealing it because I have NSF grants and I've got AFOSR, Air Force Office of Scientific Research, financial support.
36:40
And I didn't want to do anything in cryptography under those because then NSA would descend on me. To my surprise, my NSF grant monitor, when I tell him that I'm spending my own time on that, he says, no, do some of that under the NSF grant. And as I start to get good results, to my great surprise, even greater surprise,
37:01
my contract monitor at AFOSR says the same thing. So I'm starting to spend, now I can spend some of this grant money. I don't have to steal time. And then Whit Diffie shows up, which is critical. Okay, have him descend either by parachute or whatever. Actually, he came by Datsun 5-something,
37:23
whatever the Datsun was that he was driving then. So this is not somebody whom anybody in the world would say was the equivalent of your personality. This is not a similar kind of person. No, Whit had long, and still has long blonde hair. Now it's whiter.
37:41
Very counterculture. I mean, he takes wisdom of foolishness a little further than I do. And so what happened was in the fall of 1974, as I'm starting to spend more time on cryptography, but I'm also beginning to feel a little isolated.
38:01
I mean, I like being the fool and doing what no one else does, but it's also a little scary and a little lonely. I get a phone call from this guy named Whit Diffie, and he says, Alan Conheim, who heads the cryptography research group at IBM, had suggested he looked me up when he's out in the Bay Area. He'd been traveling around the country.
38:20
So we set up, I forget, it was a half hour or one hour meeting at my office about five minutes from here. And I mean, I didn't know that this was gonna be, I mean, I set up half an hour an hour, figuring, okay, it would be mildly interesting. After half an hour, an hour, we go on and on and on.
38:41
I mean, it was such a meeting of the minds, and he'd been working alone, I'd been working alone, and we had some of the same ideas. He had ideas that I hadn't had, that I liked, and vice versa. So after, I don't know, it must've been several hours of meeting with him in my office, I look at my watch and I say, I promised my wife I'd be home to watch our girls.
39:00
So this is 1974, they're three and five. I'd love to continue this, but we have to go back to my house on campus. It's very close to here, can we do that? He says, sure, he just has to let Mary Fisher, his wife, know about this. They join us for dinner at our invitation and leave at 11 o'clock at night.
39:20
And it wasn't like, oh my God, there they finally got out of here. It was just fantastic. It was a meeting of four, really, not just the two of you. Oh yeah, Mary was interested in dogs, Dorothy was very interested in dogs, so a lot of things in common. So what was the, and I know it's difficult to compress, so to speak, but the key insight that you both felt an affinity about,
39:46
that was gonna lead, just in a couple of years, to your major, major transforming case. Less than a year and a half. A year and a half. Well actually, less than a year and a half till the algorithm. I came up with the algorithm now known as Diffie-Hellman Key Exchange, although I've argued it should be called
40:01
Diffie-Hellman Merkle. And I will talk about Merkle in a second. That was in this study right down there that I can't show you because I moved a lot of junk in there, but late one night. But Whit actually was talking about public key cryptography for maybe six months or nine months. I mean, we were talking together before that. And we'd had some ideas together,
40:20
like something called the trapdoor cipher that had even preceded that. What was the problem that you needed or thought you could solve? The core? Well actually, I'm gonna trace it back to trapdoor cryptography. One of the, cryptography's an interesting system or problem. When you and I are talking,
40:41
we want secure encryption so that he can't listen in on us, the guy sitting over there. Then when I talk to him, I might not, we may not want you to listen in. And let's put that in a military context. You guys are on one, I'm actually gonna change it. You guys are on one side in a conflict and I and my guys over here
41:01
are the army on the other side. We want secure encryption that you can't read. But you might capture our encryption device and start using it against us. So we want, we realized fairly quickly is the ideal cryptographic system from a military point of view would be a trapdoor cryptographic system. One that would have secret information built into it.
41:23
You might know it's built in, but unless you know exactly what that bit sequence is, you can't break it. But if you ever capture it, and because I built that bit sequence in, I know how to break it. And from there to public key cryptography is not that big a step. Because if you can do trapdoor encryption
41:42
and generate them at will, let's say you and I want to talk securely separate from the guy behind the camera over there. I create a trapdoor crypto system. I say to both of you, because I mean, I'd like to tell it only to you, but the cameraman hears it too. You then take that trapdoor system,
42:02
encrypt a message to me, Marty, here's the key we're gonna use. You encrypt it, he can't break it. You couldn't break it if you didn't. But I can break it because I've got the trapdoor information. That's public key cryptography. So did that answer your question? Yes, but I think also in your process,
42:21
there are people thinking about that same problem but coming up with unsatisfactory, it may have been the NSA or something, unsatisfactory answers to that. Well, they weren't unsatisfactory. Part of the thing was when you go from encryption being primarily of military significance to being of commercial use,
42:41
it changes it in a major way. In the military, you have a chain of command. A private in one company does not talk to a private in another company. He talks to a sergeant, who talks to a lieutenant, who talks to the captain, who talks to the other lieutenant, sergeant, and private. So the number of connections is limited. Whereas commercially, or now,
43:03
anybody might wanna talk to anybody. So the number of keys that you need, the number of connections you wanna make, goes up literally, well, not quite exponentially, it goes up by a huge amount. And so key exchange, which was a major problem in the military, becomes an almost impossible problem in the commercial world.
43:20
And that's why public key cryptography was so important. Now, as you said, there were not just two of you in this conversation, this transformative conversation. The three of you, essentially. Can you talk about the third? Yes, the third guy's Ralph Merkle. So Whit and I are working here at Stanford. I was able to get him to put some roots down
43:41
and stay here. I was very anxious to have him stay. And he hadn't actually done the formal PhD process. Well, that's another story. We'll come to that in a minute. So we're working, and we've come up with the public key idea, but we have not yet come up with the algorithm that I talked about.
44:05
But after coming up with the basic idea, but before the algorithm, Whit, through a friend at Berkeley, hears about this student, Ralph Merkle, who's an undergraduate, now a master's student, working on cryptography, saying somewhat similar things. And Ralph, again, is a world-class fool
44:22
in the best sense of the word. He had proposed developing public key cryptography for a term project in CS 244, a Berkeley graduate course. And the professor had discouraged him from it. Now, admittedly, when he wrote on the paper, and Ralph saved it, and I scanned it for him,
44:41
it said, maybe because your explanation of idea number one, which was public key cryptography, was so muddled. So muddled, he said to his professor. Yeah, that's what the professor said to him. That maybe it was muddled. And so Ralph, independently of us, was working on related ideas. There's differences, and he didn't have digital signatures.
45:01
But he came up with his ideas actually before us, and that can be documented. But we didn't know about that, and then we each heard of the other after we had been working and had grown together. But the other thing, when Ralph submitted his paper to a journal, unlike mine, I had been invited to write a paper.
45:20
And when I came up with the Diffie-Hellman or Diffie-Hellman-Merkel key exchange algorithm in May of 1976, I presented it at another information theory symposium in June, the following month. I had a paper accepted with the general idea. Now I had a specific way to do it, a good way to do it. And the editor of the journal was at that,
45:43
who invited me to write this paper, and I asked if Whit could join me in the paper, which he'd said fine to. The editor was there, and he said, you get that result in, and I'll have it in the November issue of the transactions. And he did. So you saw the importance of it? Yes. And similarly, RSA, Ravesh Shamir,
46:00
Adam and MIT, when they came up with their algorithm, which had seen great commercial use, I was one of the reviewers. I get a letter from the editor, please review this paper as fast as possible. It may be the most important paper we ever published. Now, editors don't usually say things like that. Poor Ralph, his editor didn't say that.
46:20
Ralph's editor sent it out to review to an expert in cryptography, presumably at NSA, who said, this is not in the mainstream of cryptographic research, and questioned whether you could do what he was saying, even though he showed he had a proof of concept in it. The guy just didn't understand the paper. The editor writes back,
46:42
and Ralph again has these letters, it bothers me that you have no references. I mean, he had no bibliography in his paper. Has no one ever thought of doing anything remote or resembling this before? And the answer is, no, they hadn't. It was seminal research. Now, in the editor's defense,
47:01
Ralph should have had some references. I mean, he didn't know how to write a paper. He was either an undergraduate or a master's student when he wrote that, and with no benefit, I mean, a professor who had discouraged him. So, that's Ralph Merkle, and he deserves, in my opinion, equal credit for the invention
47:21
of the key exchange part of public key cryptography. There's two parts. The key exchange, which is what I described, and then there's digital signatures, and Ralph did not have that, admittedly, which is one reason I think the ACM award was given just to wit and me, although it's kind of a toss-up how it goes. I understand.
47:41
Digital signatures, talk about that a bit. Okay, most people, when they think of cryptography, think of privacy, not authentication, but really, cryptography is concerned with both privacy and authentication, and let me explain that and why authentication, which people don't think of,
48:01
is probably the more important of the two. Think of writing checks on your bank account. If privacy is violated, that camera guy over there can read every check you write on your account. You're unhappy if that happens. If authentication is violated, he can write any check he wants on your account, which makes you more unhappy.
48:22
The second one, and so what you need for, now, cryptography always had some form of authentication, but with public key cryptography, you get an even better form. Normal cryptography, prior to public key, would allow the two of us to communicate and prevent the cameraman
48:40
from either reading what we have written or altering what we've written, so there's both privacy and authentication, but you could alter what I've written to you and make it look like it came from me. I could alter what you've written to me because we share a common secret key in conventional cryptography. In public key cryptography,
49:01
there's a public key and a private key, and when you do digital signatures, the secret key, the private key, is used to sign the message, and the public key is used to verify it, and so you can sign checks digitally much better than we can sign checks, paper checks.
49:22
A paper check, someone might be able to change the number because the same signature is used for a $100 check or a $100 million check, whereas a digital signature depends on the contents of the message, and so my signature on a $100 check is totally different from my signature
49:41
on a $100 million check, although it uses the same private or secret key to create it. Okay, now we're gonna send your insights out into the world, and I'm just gonna put it in the category of security and what this new key exchange allows and commercial impact as well.
50:03
So security, which is both national as well as commercial, and then the commercial side. What happens when your paper is presented to the world? A lot of excitement in the academic world, the commercial world, a lot of consternation at NSA, the classified world,
50:24
and probably their foreign equivalents, and that's because they regarded cryptography as their monopoly, and they were concerned that if we tell Americans how to protect their secrets from criminals and foreign countries, we're also telling foreign countries how to protect their secrets from NSA.
50:41
We're telling terrorists and criminals how to protect their secrets. You can't get around that. Right, and that discourse goes on. More than discourse, a war initially. So my colleagues, remember the two arguments, NSA has a huge budget, how can you hope to discover something they don't know,
51:01
and if you do anything good, they'll classify it. They actually might have said, if you do anything good, they might kill you, or their foreign equivalents might kill you. Right, because the implications were that profound. Yes, and so Dorothy was very happy when this quiet war became a more public war and was covered in the New York Times.
51:22
They had an editorial supporting our position. Science Magazine had a number of articles. She said, now if something happens to you, there will be an investigation, and I'm not necessarily saying NSA would have done it, and I don't even know that I was at risk, but when you're angering not only NSA, but their Soviet equivalent. Right, right, right.
51:40
Well, the stakes were very high. Yeah. The stakes were very high, and as you say, it continues, the famous controversy with Apple and NSA in terms of. Although it's interesting, in the Apple, currently, the FBI is saying what NSA used to say 40 years ago, which is our needs take precedence over your personal,
52:00
your private needs and commercial needs. NSA, to a large extent, has been on our side. Several former directors of NSA have said the FBI was wrong and one of them even said, Jim Comey is wrong. Wow. I'd have to go get the names and even the current director of NSA. Oh, that sounds absurd.
52:21
Yeah, I can, well, actually, since this is a video, I can't send you links afterward, but they're in my computer library. Anybody can find them. I believe you. Oh, and why is that? Well, about two, two and a half years ago, Admiral Inman, who was the director of NSA when we were publishing these papers and who, loosely speaking,
52:40
wanted to throw me in jail for publishing them, he later became a friend. I mean, initially an adversary and then friend, cautiously at first, but in an interview, he was asked, with what he now knows, would he still try to suppress our work? And he said, quite the opposite. I would try to get it out as quickly as possible
53:01
because he now sees that from the broad perspective of national security, commercial encryption, strong commercial encryption is very important, and he cited theft by, presumably, the Chinese of jet fighter plans from American businesses, as an example.
53:21
Among the many implications and impact of your work, some attribute it to that the World Wide Web would, as we know it, wouldn't really be working without this. Is that an overstatement or is it, do you think? Well, it would work for anything unconfidential, but all the electronic banking you do,
53:43
when you purchase things with a credit card, and about three years, four years ago, someone told me that trillions of dollars a day in financial transactions were protected using our technology, and I said, no, you mean trillions of dollars a year? And he said, no, I mean trillions of dollars a day, and I checked and he's right.
54:01
Foreign exchange transactions, which are all protected by this, are about five trillion dollars a day. Unfortunately, our patents ran out. No, but they must have helped for a while. We made almost no money from our patents. You made almost no money? Yeah, RSA sold their patents for 200, their company for $250 million.
54:22
There was a patent fight between RSA, the MIT guys, and Stanford, and bottom line is, they outspent us and we lost. Although, maybe it's different. I'm friends with them now. I was really pissed at them for a long time, but we're good friends. Fairly enough. So, I want to now talk about-
54:41
No, actually, they might, they could, I went back and thought through that fight from their point of view, because just like the way our marriage went from being headed for divorce 40 years ago to not having had a single fight in probably 15 years and being in love the way we were when we first met,
55:02
I rethought the patent fight. Oh, the one way we did that is, when Dorothy does something that annoys me, instead of just being annoyed, I would try to think it through from her perspective. I do try to think it through from her perspective, and it's often very different from what I thought. In the same way, I went back and rethought the patent fight that we had with RSA,
55:22
and I could see how from, I don't know for sure, but from their perspective, they might think I started the whole thing. Right. I want to talk about at the end, to finish the interview about the ethicist, because you're one of the scientists, technology scientists, who thinks about broadly
55:40
the implications of science, technology, security, privacy, and so forth. At what point in your career did you begin to become as outspoken on the ethics of science and really of relationships
56:00
in the world as they are affected by it? How did you begin to? 1981. 1981, just a moment. Yeah, well, so what happened was, the short answer is what caused me to make this shift is my wife wanting to preserve my marriage, coming to see that my marriage was in trouble. I was so busy working that I changed from the way I was
56:23
when I took the week off after getting that great result. I had become a slave driver to myself. But Dorothy was in touch with that, and she was looking for catalysts, and she tried several different things, because she didn't know what to do either, and she was making mistakes just like I was.
56:42
But then in 1980, she found a group that no longer exists, so we're not recruiting people for the group, and I was very arm's length at first, but by the summer of 1981, when she dragged me to enough meetings and we'd done enough work, that's when I first realized how my mother must have felt
57:00
when my father went off. I mean, he'd been in the Army for a couple years, but when he went off overseas to the South Pacific, I'd never thought about that before. We did a lot of deep personal work. And then in the summer of 1981, we took a week, which I never would have taken a year earlier, to go to a seminar looking at the bigger issues
57:23
of the world, the bigger issues of our lives. And during that week, I saw that these people knew something I had to learn if my marriage was going to survive. And I dropped my resistance, threw my wad in with them, but they also were working on global issues.
57:41
And the fact was, at that week-long seminar that I saw Day After Trinity, a documentary about the making of the first atom bomb, because the first test in the New Mexico desert was called Trinity Site. And in that documentary, they interview about five or six
58:00
of the scientists, engineers who worked on the Manhattan Project, and they ask each one of them, what was your motivation? And each of them says, Nazi Germany. I mean, fission had been discovered in Germany in the late 30s. If Hitler got the bomb first, it would be 1,000 years of dark ages. We had to, and you could just see they're reliving the excitement they felt working on this important project
58:23
to save the world from disaster. But in that same documentary, they come back to each one of them and say, so when Hitler was defeated, when our only enemy was Japan, and your stated, they don't say it, but it's implicit, your stated motivation was gone. Why did you keep working on this horrible weapon?
58:41
And their faces drop, one of them even develops kind of nervous twitch, Robert Wilson. He actually vomited, I found out later, this isn't in the documentary, when he heard that the bomb had dropped on Hiroshima, he was going from one lab to another at Los Alamos, and he just stopped and threw up. And watching the film, I could not be sure,
59:01
but I believe they did what I had done in 1976 when I had to decide whether to go public with my fight with NSA. I was trying to figure out the right thing to do, and the idea popped into my head, forget about what's right or wrong, you've got a tiger by the tail, run with it, you'll never have as much chance to be well-known,
59:21
be famous, infamous, whatever. At the time, I thought I brushed that, I call it the devil on my shoulder, like in the movies. I thought I brushed him off my shoulder. But watching Day After Trinity, five years later, because that was 1981 now, I saw that I had fooled myself, I had figured out what I wanted to do, and then gone and done it,
59:42
then come up with the rationalization for why what I wanted to do was the right thing, and I believe the Manhattan Project scientists had done the same thing, and I vowed never to do that again. Although, actually I'm gonna refer people to a book my wife and I finished, and it's not a book sales job because people can download a free PDF.
01:00:00
It's a new map dot-com a new map three words run together and there's a get the book has that place we can download a free PDF and search on devil on my shoulder or a Day after Trinity would get it and the stories in there About why even after I made that vow that I was never gonna fool myself again Some years later when I was in the patent fight with RSA. I couldn't be sure I wasn't fooling myself
01:00:25
I wanted to do something if we made good business sense But by the way, it also had the chance to really get them. In fact, someone came to me and said You helped me do this. We'll get those RSA bastards by the balls. He hits way spoke His exact words and I didn't want to I mean
01:00:42
The eventual part of me which was still active at the time I couldn't be sure that wasn't fooling myself and Dorothy came up with a wonderful Solution which is described in the book to make sure I wasn't fooling myself
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