I am able to decrypt vigenere cipher text using the index of coincidence and chi test.
However out of interested how do you go about attacking ciphertext that was encrypted using a mix alphabet shifted 26 times?
Also what about a ciphertext that has been encrypted with 26 random alphabets? so each line in the tableau is random.
Googling seems to bring up the basic vigenere, either an example of a link to a resource would be good.