Interview with David Kahn (Page 2)
J: Alright. When your book the codebreakers was first published, it was the definitive account about the history of cryptography. Considering how little information was available to the general public back then, how did you go about collecting information?
DK: I had been a newspaper reporter before I started writing that book. And I still in a way consider myself a newspaper reporter. So the way I went about collecting that information was by going to the footnotes of the books that were there and tracing them back to their scholarly sources - Number one. Number two - for more modern things, where material had not yet been published, I went and spoke to the people I knew about what code breaking or code making work they had done. So, I attempted to find out as much as I could in that respect. I might say that one of the great failures, or possibly the greatest failure of that book was that when it came out in 1967, I didn't know anything about the British success in breaking codes, in particular the German enigma codes during WW II and that's the great lack in that book and we had to make it up in a subsequent edition which came out, I think, in 1996. But the answer to your question is, I tracked it down in scholarly research through footnotes and by interviewing people.
J: Ok. Could you relate to us an event from the history of cryptography that interests you or perhaps even intrigues you so much that you wish that you were actually there when it happened?
DK: Yes! The one I would have liked have been at was the American solution of the Japanese PURPLE cipher machine in September of 1940, when a woman, Genevieve Grotjan was working away on some solutions attempting to solve things, and suddenly realized that she had discovered some combinations of letters, I don't really know what they are but some combinations of letters which proved that the attack method that the United States was using was on the right track. They were doing it correctly, and once she had discovered those points, they pressed ahead and they continued to solve that PURPLE machine which enabled the United States to help not so much in the Pacific war even though it was a Japanese machine, but more in the European war because the Japanese military attach, later the ambassador in Germany was reporting a lot of material back to Japan using this machine including a great deal about what the Germans were doing and their fortification in the Atlantic war and places like that. And this material helped the Americans in attacking the great Overlord invasion of 1944. It helped them in attacking successfully the continent of Europe. So that was something I would have liked very much to have been at.
J: Ok. How have the cryptographic laws changed over the time?
DK: Yes, I think that they have attempted to keep codes and ciphers strictly under wraps as much as they could as soon as they realized how important they were. So there has been a continual tightening of laws, on the part of all governments, not just the part of the United States but other countries as well, to keep material from the public domain and into the Government domain as much as they could. Its not only the United states which I am most familiar with, but also the United Kingdom, France and Germany all have very strict laws restraining the public from doing any kind of, not any kind of, but most Cryptologic research and keeping under as much government control as they possibly could.
J: Ok. Which period in your opinion was the defining period in the history of cryptography?
DK: WWII. No I bet I would take that back. I would say it would be WWI. Thinking about that again. WWI was the defining moment in cryptography for the following reason - Radio had come into wide spread use in world war one. And radio made it possible for nations to intercept the messages of other nations and if they were coded, they broke them. And as a consequence of these interceptions and these breaking of these codes, nations in WWI gained victory after victory. For example, the battle of Tannenberg in August 1914 enabled the Germans to defeat the Russians and keep on defeating them until, you know, they knocked out the Czar and resulted in Russia's leaving the war. Then there were a number of battles on the Western front which played a role in that war and those were won to a large degree on the basis of breaking of code breaking interception. And finally, the so called Zimmermann telegram which was a message between the German foreign minister and the president of Mexico, which was intercepted by the British, decoded and given to the United States, and it told the Americans that the Mexicans were being asked to have an alliance with the Germans against the United States. And suddenly, when this was made public 6 weeks after that was made public, the US entered the war. So this was possibly the greatest and most important example of code breaking. And so this all took place on WWI and as a consequence of that, code breaking really became important and governments realized how important it was. Countries that had not have code breaking units like the United States and the United Kingdom suddenly put them into effect. So the short answer to your question is that World War I was the most important time in the history of code breaking.
J: Yeah. It seems like wars have accelerated the history of cryptography. We are a part of an international team with members from India, Columbia and the UK. Could you brief us on some of the major contributions of these countries to the history of cryptography?
DK: Well India made important contributions but back in the prehistoric time when they were "Arthashasthra" and those other treatises of Government. They mention, I think, code breaking there. What Columbia did or not, I don't know. I don't know anything about what Columbia did. What the UK did of course, its major contribution was the solution of the Enigma machine in WW II and mechanizing the solution using the so cold bombs to help solve messages and reconstruct the keys for an entire key net and read all those messages. That would be the great contribution of the United Kingdom into code breaking, I would say.
J: Ok sir. So that's the end of our questions Mr.David Kahn. Would you like to add anything to these, as in anything we probably missed out that we should know about the history of cryptography?
DK: No I think you had it quite well. With one exception, possibly - the invention of the one time pad, the only theoretically and practically unbreakable cipher system. This was devised by a man named Mauborgne, first name Joseph, Who was a Signal Corps officer and in working with a man named Vernam who had automated cryptography the first time, developed a system automatically enciphering and transmitting in code form the messages. In other words, online encryption. He worked with this man Vernam and realized that the key had to be absolutely random and absolutely endless. And when you have a random endless system, it's unbreakable. So this was a very important development in the history of codes and ciphers and it was done around the very end, December of 1917 or the beginning of January of 1918 and this system, the one time system is a system that is widely used even today especially by spies and all that. And that would be an important aspect I think in the development of codes and ciphers.
J: Ok that was fascinating sir. So, thank you Mr. Kahn for your time and for answering all our questions. It was nice talking to you sir.
DK: Same here and the best of luck with your project.
J: Yeah thank you very much sir.
DK: Thanks a lot.