Viewing Single Post From: How Much Of Cytographic History Can You Believe?

Viewing Single Post From: How Much Of Cytographic History Can You Believe?
jdege	Dec 19 2006, 07:09 PM
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.

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