I have a question. I read that friedman's test was something like this:
Friedman's test tries to find out the period of the cipher by calculating several values of Κ (C, C ^ n) n, where C ^ n represents the ciphertext with n shifts on the left, thus determining the value most likely the figure.
But deep down, what does Κ do? overlap the two texts and see indices of coincidence? Can anyone explain this method better?