Vigenere Cipher Cracker Tool

Enter the ciphertext and the keyword length in the appropriate boxes, and click the "initialize" button. Dashes indicate unknown letters in the plaintext and keyword.

To decrypt, guess a letter in the plaintext or the keyword - replace the dash with the desired letter. Click "update keyword" to update the keyword based on the current plaintext or "update plaintext" to update the plaintext based on the current keyword. You can also use "reset keyword" and "reset plaintext" to reset the keyword/plaintext to only what is known given the current state of the other. (The different between "update" and "reset" is that "update" won't change a letter for which the corresponding letter in the other thing is "-", while "reset" will.) To "unguess" a plaintext or keyword letter, replace it with a dash. You can start over from scratch by clicking "initialize".