Plaintext:
This was a Caesar shift of seventeen followed by a transposition of rows and columns. This, of course, retains the letter frequencies of English which probably helped you decipher this. In this case, the two methods of encryption commute. However, this isn’t always the case. Apart from some special cases, if we use a Vigenere cipher and then a transposition, we will get a different result, depending on which order we do them in. Can you find any cases where they will commute?
Method to solve:
Number of characters in the message is 384, which has the factors 1,2,3,4,6,8,12,16,24,32,48,64,96,128,192,384. By the hint from the previous cipher challenge, it should be a combination of transposition and substitution.
We can try to transpose the message into a number of columns, where that number should be one of the factors of 384. After each transposition, see if it contains any repeating three letter words, which should be 'the' in the message. If so, that might be the right transposition. I tried the factors from 3 to 16. I stopped at 16 because I see repeating 'kyv'. I now know that 'kyv' is 'the'. After an observation, it is a Caesar shift, so the other subsitutions are known immediately.