Dynamic Hill cipher
in [Cryptography]
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From: Mok-Kong Shen on 1 May 2010 18:40 Maaartin wrote: > Mok-Kong Shen wrote: >> A question of ignorance: What do you denote by LCM? (I only know the >> meaning "least common multiple".) > > My fault, I meant LCG (Linear congruential generator). I don't understand why you are looking for references on linear generators (the PRNG of the contest is non-linear!!). But, anyway, the following is a paper satisfying what you asked: J. Boyar, Inferring sequences produced by pseudo-random number generators, JACM 36 (1989), pp 129-141. > >> BTW, in a previous post I have lowered the threshold of the difficulty >> of the challenge task. On the other hand, for obvious reasons, like in >> all contests, I am taking the liberty to set the closing date of >> acceptance of the challenge offer on 1st June, 2010. > > Ok, I need to think about it and to specify it in a bullet-proof way. > It may happen, I found out, that it's too easy; in this case I'll tell > you. If the matter turns out to be indeed so trivially simple (as some experts had claimed) that you could convince me of the evidently easy realizability of a program to solve for the sequence mentioned in a previous post of mine, you would win the prize without needing to do any programming work. Regards, M. K. Shen
From: Bryan on 2 May 2010 02:30 Mok-Kong Shen wrote: > Maaartin wrote: > I don't understand why you are looking for references on linear > generators (the PRNG of the contest is non-linear!!). Which is a disingenuous requirement, Mr. Shen. You had merely required that the generator have reasonable statistical properties. People suggested the linear case would be a promising starting point to analyze your scheme, and you rejected the idea: Mok-Kong Shen had written: | Because the anylyst couldn't even come to "any" output values of the PRNG (there are | no sufficient number of equations that could be set up), then it is "absolutely" irrelvant, | whether the PRNG is linear, non-linear." You insisted that you could not begin to crypanalyze a linear case, but you make it Maaartin's task to produce a fully-automated break a of non-linear version. To make your challenge fair, you, Mr. Shen should provide a program to test the statistics of PRNG output, and show that truly random streams pass with overwhelming probability. Maaartin must then produce a PRNG which passes your tests, and break your scheme with a tractable known- plaintext attack where that same PRNG provides the Hill-matrix entries. > If the matter turns out to be indeed so trivially simple (as some > experts had claimed) that you could convince me of the evidently easy > realizability of a program to solve for the sequence mentioned in a > previous post of mine, you would win the prize without needing to do > any programming work. Mr. Shen, I've been through trying to convince you that systems are solvable. See, for example: http://groups.google.com/group/sci.crypt/browse_frm/thread/a89ecba43a7961e8 or: http://groups.google.com/group/sci.crypt/browse_frm/thread/6b8869d787ad4ed4 Convincing you of anything is an unfair challenge. -- --Bryan
From: Mok-Kong Shen on 2 May 2010 06:40 Mok-Kong Shen wrote: > Maaartin wrote: [snip] Mr. Maaartin, since the challenge is offered to you personally, I'll not consider posts of others to be of any significance for our potential agreement. You could express detailed wishes, of course. But I think you would deem it to be correct on my part, when I say that the "foundation" of any negotiations "is" my original concrete offer as clearly stated in my post of 24.04.2010 19:02. That is, tiny points may be discussed, like in any business contracts, but there shouldn't be big "revisions". M. K. Shen
From: Mok-Kong Shen on 2 May 2010 07:38 Am 02.05.2010 12:40, schrieb Mok-Kong Shen: > Mok-Kong Shen wrote: >> Maaartin wrote: > [snip] > > Mr. Maaartin, since the challenge is offered to you personally, > I'll not consider posts of others to be of any significance for > our potential agreement. You could express detailed wishes, of > course. But I think you would deem it to be correct on my part, when > I say that the "foundation" of any negotiations "is" my original > concrete offer as clearly stated in my post of 24.04.2010 19:02. > That is, tiny points may be discussed, like in any business contracts, > but there shouldn't be big "revisions". Sorry, typo: Please read 29.04.2010 19:02. Regards, M. K. Shen
From: Maaartin on 2 May 2010 09:02
I think, it's quite easy. I think, I can write a program doing the encryption in couple of hours, and the cracker, too. The funny thing about it: I need neither any help, nor reading any papers, nor any knowledge of cryptographic attacks. In case I'm right, I'll post it here and don't take the challenge. On May 2, 6:56 am, Mok-Kong Shen <mok-kong.s...(a)t-online.de> wrote: > I don't know but I believe that a subscriber of ACM's digital library > can certainly access it online. I'm not a subscriber, and I neither study nor work for a large company subscribing it. But it doesn't matter, I don't need it. |