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I just want to make sure I fully understand the challenge:

1) Is the homophone table known or unknown?

2) Is the homophone table is unknown, then basically knowing the alphabet order is not really useful, right?

I read your master thesis, which is based on sequential use of homophones. And also a work by Campos, F.A.; Gascon, A.; Latorre, J.M.; Soler, J. R, which relies on a known homophone table. So if I understand well, none of these weaknesses is available and there is a need for a powerful generic case (all unknown) algorithm to solve the challenges, or did I misunderstand the wording of the challenge.

Many thanks

George

Hi George,

Thanks for the questions and your interest in the challenges.

1) Is the homophone table known or unknown?

Yes, in both challenges (part 1 and part 2), the homophones table is unknown.

2) Is the homophone table is unknown, then basically knowing the alphabet order is not really useful, right?

Yes, exactly.

For the first challenge (part 1) the homophones were selected sequentially, then you can use the method proposed in my thesis to reconstruct some of the columns of the homophones table (Phase 1). Beyond this point, it can be used a generic tool for solving monoalphabetic ciphers.

For the second challenge (part 2), the homophones were randomly selected. Then, the weakness presented in the first challenge is no longer there. Thus, in this case you need a generic algorithm for solving homophonic ciphers. However, note that it can be useful to know that each column of the table contains either 3 or 4 homophones. This makes the attack easier.

Any ideas for solving the third challenge are very welcome. It would be really good for the historians to decrypt this telegram.

Good luck by solving the challenges :)

Best regards

Luis