[Cryptography] Can Anyone Solve This?

[David Kane-Parry]

On Tue, Nov 7, 2023 at 11:30 PM Bradley Siesko <sieskob at slsd.org> wrote:
>> On Tue, Nov 7, 2023 at 12:34 AM ithinkimparanoide via cryptography <
cryptography at metzdowd.com> wrote:
>>> I have one problem I cannot solve. Actually, two. This is a cipher that
someone ('anonymous sender') has sent to me few months ago and it seems
that it is impossible to decipher it.
>>
>> It's not impossible. It can even be done by hand.
>
> How would you start to solve this problem?

Start with https://en.wikipedia.org/wiki/Index_of_coincidence . For values
similar to plain text, the ciphertext is probably from a transposition or
monoalphabetic cipher. For values dissimilar to plain text, the ciphertext
is probably from a polyalphabetic cipher.

Beyond that, I wouldn't want to spoil the fun for anyone. I will, however,
happily recommend https://inventwithpython.com/cracking/ for high school
students or anyone else who might be a complete beginner.

- d.
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