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Dear gfoot can you give any hint what to do to solve this challenge

I knew it was kind of hard, but I'm surprised nobody has solved it yet. This one was actually just a warm-up - I sent adum a much more complex one too! I thought tails would solve this simple one within 24 hours or something. Maybe he just hasn't seen it yet...

It's an old-fashioned technique, and not very sophisticated, but its cryptanalysis method doesn't show up much either on Google or in the only book I own on cryptography. As such, I think you'll need to roll your own algorithms for solving it.

Thank you for your expectation, but I have already spent several hours for this challenge. Hmmm... I'll try harder.

I think i got the type of chipher (as always: just consider the caption) - but the cryptanalysis is really hard.

the same for me, if it is what it seems to be, then every approach to break the code failed so far.

It is hard, much harder than I thought. I wrote an analysis tool to see exactly how hard it was going to be, but it looks like I underestimated. The key is to look at relationships rather than individual values.

adum asked me to post an easier example, but I forgot - I'll send it soon though. It might help you work out how your analysis should work.

Well, I solved the challenge some days ago (and answered the question correctly). Now the challenge is gone, at least from my perspective. Accessing the challenge url directly tells my that I am not ready for this challenge. What happened?

There's a warm-up challenge before it now, which you need to solve before the other will appear again.

Well I decrypted it but I can't answer the question! The number 43 is not used in the text - is that spoiling my key input?

EDIT - got it, see the rest of this post for a clue!

What form should the answer have? Is it like in warmup?
Or there should be english text after deciphering?

Thanks

Damn, I have hoped there is thread for solvers there ...

[edit] ... moved there [/edit]

I only searched for different numbers, that represent the same letter with my code (by calculating some kind of square difference).
Then it was only a matter of guessing and frequency analysis. [sentence removed]

And I have no idea, what you did here

Hmmm I have not spoiled the question of presented alphabet ...

The beam search is basically maintaining the best "window" solutions according to evaluation of partially filled plaintext (corresponding to partial keys). Only keys in the window are extended for the next generation. ... So you should have evaluator of partial plain texts "language model".
Good ordering of where to extend the keys helps. (For example first cipher letter 01, next cipher letter 07 ...)

You hope to have language model which evaluates best the plain text corresponding to original plain text.
And you hope all the generations of partial plaintexts corresponding to the key extesions would fit to the corresponding window.

Moved to solved section ...

Hippo wrote:Damn, I have hoped there is thread for solvers there ...

There are threads for both challenges in the "Challenges Solved" section.

Sounds Same Warmup: http://www.hacker.org/forum/viewtopic.php?t=1280
All Sound Same: http://www.hacker.org/forum/viewtopic.php?t=1261