How Much Of Cytographic History Can You Believe?

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How Much Of Cytographic History Can You Believe?
Topic Started: Dec 19 2006, 07:09 PM (548 Views)
jdege	Dec 19 2006, 07:09 PM Post #1
Elite member Posts: 263 Group: Admin Member #246 Joined: December 7, 2006	How much of cytographic history can you believe? It's a field in which many, if not most, of the participants were trying to keep secrets. It's not a field that's generally known for its openness. How much of what we read in the histories can we believe? Think about DES. When it came out, the experts in the overt cryptography community immediately jumped on the constant values used in the S-boxes. IBM refused to discuss the criteria they had used in choosing them. Which lead many to suspect that they had been recommended by the NSA, during IBM's consultation with them, so as to give the NSA a back-door. A decade later, Shamir and others developed differential cryptanalysis, and discovered that DES was proof against it - that the number of S-box iteratons and the constants used had to have been specifically chosen to protect against differential cryptanalysis. Turns out the the IBM researchers had discovered the technique in the seventies, found out that the NSA had discovered it earlier, designed DES to be proof against it, but never said a word about it until after it had been discovered by someone else. Has this happened before? Almost certainly. Consider the "Vigenere" [sic] cipher. It was first published by Belaso in 1553, building on the work of Alberti and Trithemius. According to the histories, the first publication of a method for breaking it was Kasiski's, in 1863. But had anyone known if it before? Certainly. We know that Babbage had used the technique in 1854. Was he the first? I find it impossible to believe so. The "Vigenere" was first published in 1553. In 1563, Della Porta described a similar system that used mixed alphabets. In 1585 Vigenere described a number of systems using autokeys. Why new systems specifically designed to address weaknesses of "Vigenere", if "Vigenere" was unbreakable? And why did the professional cryptographers continue to use nomenclators from the 16th through the 18th centuries, if they believed that "Vigenere" was unbreakable. I don't think it was. I think that the method used by Babbage and Kasiski had been known, at least by 1570 or 1580, to those in the covert cryptography community. That it was never a secure system. And that's why the professionals didn't use it. And, for that matter, why they didn't use Della Porta's or Vigenere's improvements, because neither of them produced a secure system.
	When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.


Donald	Dec 20 2006, 02:31 AM Post #2
Elite member Posts: 454 Group: Trusted Member Member #8 Joined: September 2, 2005	Yes. You have a VERY valid point, and one that I feel Kahn acknowledges in his work. Look at poor Turing. A war hero, and he couldn't tell anyone. Cryptography is the art of SECRET writing, which means will will probably NEVER know many of the twists and turns it's history has taken. But we do know a surprising amount. I recommend Singh's "The Code Book" for an introduction to the history of cryptography that even a non-crypto buff could enjoy. And Kahn is essential for the serious enthusiast.



jdege	Dec 20 2006, 07:35 PM Post #3
Elite member Posts: 263 Group: Admin Member #246 Joined: December 7, 2006	Donald Dec 20 2006, 02:31 AM I recommend Singh's "The Code Book" for an introduction to the history of cryptography that even a non-crypto buff could enjoy. And Kahn is essential for the serious enthusiast. I've not read Singh. All of the reviews I've seen, except one, were glowing. But that one raises serious questions: http://www.ams.org/notices/200003/rev-reeds.pdf
	When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.


Donald	Dec 21 2006, 06:48 AM Post #4
Elite member Posts: 454 Group: Trusted Member Member #8 Joined: September 2, 2005	The reviewer is correct, Singh is not as accurate, and certainly not as thorough as Kahn. However, I think he's overestimated the importance of the errors. Let's compare it to, say, "The Davinci Code". Cryptographers no run into people all the time who THINK they learned something about cryptography from that book, but now have bad information about the very basics of crypto, such as what is a Caesar cipher. This is BAD for cryptography. But I have yet to see anyone posting on Sci.crypt (or here) with factual errors that they picked up from Singh. that's because any mistakes Singh made were in the rather esoteric areas of cryptography and its history, not in the basics. Thats why I still recommend "The Code Book" as an excellent introduction to cryptography for the general population. It manages to make Crypto and it's history exciting and gets across most of the important concepts. People who take further interest then need to move on to Kahn. But even those who don't will have BETTER information about Crypto from reading "The Code Book" than they had before. And any mistakes they make because they got it out of Singh will probably be drowned out by the mistakes they make because they just forgot details or got confused.



jdege	Dec 21 2006, 03:11 PM Post #5
Elite member Posts: 263 Group: Admin Member #246 Joined: December 7, 2006	Donald Dec 21 2006, 06:48 AM The reviewer is correct, Singh is not as accurate, and certainly not as thorough as Kahn. However, I think he's overestimated the importance of the errors. The review was published in the "Notices of the American Mathematical Society". The reviewer writes: "The mathematical basis for the initial Polish success was the well-known fact that the cycle type of a permutation is invariant under conjugation: when one writes the permutations t and s t s^-1 as the products of disjoint cycles, the same lengths appear with the same multiplicities." Perhaps in his circle that's a well-known fact. But when I asked around the lunchroom the other day, it didn't seem to be in mine.
	When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.


Donald	Dec 21 2006, 11:05 PM Post #6
Elite member Posts: 454 Group: Trusted Member Member #8 Joined: September 2, 2005	Quote: Perhaps in his circle that's a well-known fact. But when I asked around the lunchroom the other day, it didn't seem to be in mine. ha! yes, exactly. Better accuracy would be, well, better, but the kind of mistakes Singh makes are pretty esoteric.



osric	Aug 1 2009, 08:44 AM Post #7
Advanced Member Posts: 51 Group: Members Member #3,254 Joined: March 15, 2009	Quote: I've not read Singh. All of the reviews I've seen, except one, were glowing. But that one raises serious questions: http://www.ams.org/notices/200003/rev-reeds.pdf I hope that this comment will not discourage anyone from reading Simon Singh's acclaimed book, whether or not they are interested at this point in time in ciphers. It was this book that catalyzed my interest in Cryptology, and so opened horizons to a new and fascinating world. It is well worth reading, warts and all, and like Donald I strongly recommend it. The criticisms mentioned from a mathematician's journal are no doubt valid (I've not checked them) but are totally irrelevant to anyone but mathematical geeks -- and certainly are irrelevant to normal readers. The great service of Simon Singh's book is to explain things in ordinary language that people can understand, in a way that is highly readable. If along the way he slips up on odd occasions in talking about the square root of minus one, then the cognoscienti may be outraged but the rest of us will neither notice nor appreciate that there is a problem.



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