## Beaufort cipher## From CryptoDox, The Online Encyclopedia on Cryptography and Information SecurityThe Beaufort cipher, created by Sir Francis Beaufort, is a substitution cipher. Since the encryption and decryption process are identical, the Beaufort cipher is a reciprocal cipher. The Beaufort cipher uses the same tabula recta as the VigenĂ¨re cipher: ABCDEFGHIJKLMNOPQRSTUVWXYZ BCDEFGHIJKLMNOPQRSTUVWXYZA CDEFGHIJKLMNOPQRSTUVWXYZAB DEFGHIJKLMNOPQRSTUVWXYZABC EFGHIJKLMNOPQRSTUVWXYZABCD FGHIJKLMNOPQRSTUVWXYZABCDE GHIJKLMNOPQRSTUVWXYZABCDEF HIJKLMNOPQRSTUVWXYZABCDEFG IJKLMNOPQRSTUVWXYZABCDEFGH JKLMNOPQRSTUVWXYZABCDEFGHI KLMNOPQRSTUVWXYZABCDEFGHIJ LMNOPQRSTUVWXYZABCDEFGHIJK MNOPQRSTUVWXYZABCDEFGHIJKL NOPQRSTUVWXYZABCDEFGHIJKLM OPQRSTUVWXYZABCDEFGHIJKLMN PQRSTUVWXYZABCDEFGHIJKLMNO QRSTUVWXYZABCDEFGHIJKLMNOP RSTUVWXYZABCDEFGHIJKLMNOPQ STUVWXYZABCDEFGHIJKLMNOPQR TUVWXYZABCDEFGHIJKLMNOPQRS UVWXYZABCDEFGHIJKLMNOPQRST VWXYZABCDEFGHIJKLMNOPQRSTU WXYZABCDEFGHIJKLMNOPQRSTUV XYZABCDEFGHIJKLMNOPQRSTUVW YZABCDEFGHIJKLMNOPQRSTUVWX ZABCDEFGHIJKLMNOPQRSTUVWXY Like all symmetrical ciphers, the Beaufort cipher requires both the sender and the recipient to know the same secret key. For example, suppose that the plaintext to be encrypted is: ATTACKATDAWN And suppose that both the sender and the recipient know the secret key, QUICK The person sending the message repeats the keyword until it matches the length of the plaintext. Each letter of the plaintext is enciphered using the column that starts with that letter, finding the position of the key letter in that column, and then taking the first letter of the row where that key letter was found. For the second letter of the plaintext, the second letter of the key is used: in column T, the letter U is found in row B. The rest of the plaintext is enciphered in a similar fashion: ATTACKATDAWN (plaintext) QUICKQUICKQU (key) QBPCIGUPZKUH (ciphertext)
## strength and cryptanalysisThe Beaufort cipher is no stronger or weaker than VigenĂ¨re; the method to crack it is the same. ... The Beaufort cipher can also be viewed algebraically.
If the letters and decryption,
## For further reading |