You can paste your own ciphertext into the box below or you can try to crack the the ciphertext that is already there. The first step in cracking the Vigenère cipher is to look for sequences of letters that appear more than once in the ciphertext. The most likely reason for such repetitions is that the same sequence of letters in the plaintext has been enciphered using the same part of the key. Click the button labelled 'Find Repeated Sequences' to perform this analysis.The repeated sequences may take a moment or two to appear.