How would you tackle the problem of finding the key (you don't know the length) to a Hill cipher when knowing only one 12-letter word of plaintext and its corresponding ciphertext?
CONVERSATION has been encoded as SQZHUSSUDYKP with standard alphabet (A=0, Z=25). The key, as I said, is unknown with unknown size.
I am not asking for a solution, but for tips and guidance. Any help will be much appreciated.