A Beaufort cipher (originated by Bellaso, misattributed to Vigenere) uses a multi-alphabet table like the one on the left. The key uses one axis, the message text the other axis, to creates an output character. The key must be as long as the message, so repeat the key as needed, or use a key as long as the message for good security. The most common algorithms using this 'tabula recta': Vigenere (vee'-zhe-nair): - find the message letter in the top row; - find the corresponding key-letter in the first column; - the enciphered letter is at the intersection. Beaufort (bow'-fort): - find the message-letter in the top row; - trace the column down to the corresponding key-letter; - the enciphered letter is in the first column. Repeat for each letter in the message. The Vigenere cipher can be used in reverse or on the alternative axis, to create variants. Beaufort, on the other hand, is symmetrical, so either orientation produces the same result. (To see what this means, encode something, copy the encrypted text to the Clear box, and encode it again.) Choose an algorithm:
Click on any character in Key, Clear, or Encoded text to show its encryption..decryption path.