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| jdege | Mar 25 2009, 01:34 PM |
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First, are you Anchises? Hello, I am Peristalsis.
I'm running on a 1.2GHz AMD Sempron. I'm a computer programmer - I have no interest at all in chasing the latest computer hardware. And as for my cryptarithm program, it was something I threw together in a hurry because I have absolutely no interest in cryptarithms. I'm sure that there are faster ways of doing things.
I would be interested.
And I'm afraid you're not going to find much help from anyone in this forum. There are only three or four of us who seem to have written hill-climbers, and perhaps only one of us who's ever tried to apply them to ADFGVX, and he seems to have had far less success than you have had.
Actually, I was thinking of Jim Gillogly's publication of his ciphertext only solution for Enigma. His solver would work reliably on most messages over, IIRC, 420 characters. And since he'd found several messages of over 420 characters within the archives of historical Enigma messages, he concluded that it would have worked at least part of the time on the original traffic. Someone else pointed out that those longer messages were in fact concatenations of multi-part messages, and that no individual part ever exceeded 200 characters, at which length Gillogly's attack never worked at all. You've developed an attack that works on a sophisticated WWI cipher, had they used keys that were half the length of the keys they actually used. I don't mean that to belittle your work, just as I don't mean to belittle Gillogly's work. I'm just fascinated that these guys - who could never have foreseen the types of attacks you've developed, nevertheless had enough foresight to choose message and key lengths that would have forestalled them.
What was it Reagan used to say? "They say there aren't any simple answers. They're wrong. There are simple answers, there just aren't any easy answers."
If I were to address this problem, I'd be doing exactly what you have been doing. 1st. make sure that the attack on the substitution phase worked. 2nd, make sure that the scoring routine worked - by testing with exhaustive search of small transposition keys 3rd, try to work out where it is, or why it is, that a heuristic search of the transposition key space goes wrong. In that, I can think of two possibilities. 1, the scoring routine doesn't give the highest score to the right anwser. Or 2, the adjacency search doesn't include keys that really should be considered neighbors. (I'm thinking of the way that Playfair breakers often work better when you include flipped key squares, instead of just swapped letters, as neighboring keys). I'd think you'd be already be certain that your scoring routine was successfully assigning the highest score to the proper transposition. When you were trying to hill-climb the transpositions, what were you considering as neighboring keys? |
| When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl. | |
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| Brute Forcing The Adfgvx Cipher · General | |
8:13 PM Nov 27
