1. Home
  2. Encrypt & Decrypt
  3. #

Beaufort Cipher

Keyword

Beaufort Cipher, is a polyalphabetic substitution cipher created by Sir Francis Beaufort that is similar to the Vigenère Cipher, except that it enciphers characters in a slightly different manner.


The 'key' for a Beaufort Cipher is a key word. e.g. 'FORTIFICATION'. It uses the following tableau (the 'tabula recta') to encipher the plaintext:

 
    A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
    ---------------------------------------------------
A   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
B   B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
C   C D E F G H I J K L M N O P Q R S T U V W X Y Z A B
D   D E F G H I J K L M N O P Q R S T U V W X Y Z A B C
E   E F G H I J K L M N O P Q R S T U V W X Y Z A B C D
F   F G H I J K L M N O P Q R S T U V W X Y Z A B C D E
G   G H I J K L M N O P Q R S T U V W X Y Z A B C D E F
H   H I J K L M N O P Q R S T U V W X Y Z A B C D E F G
I   I J K L M N O P Q R S T U V W X Y Z A B C D E F G H
J   J K L M N O P Q R S T U V W X Y Z A B C D E F G H I
K   K L M N O P Q R S T U V W X Y Z A B C D E F G H I J
L   L M N O P Q R S T U V W X Y Z A B C D E F G H I J K
M   M N O P Q R S T U V W X Y Z A B C D E F G H I J K L
N   N O P Q R S T U V W X Y Z A B C D E F G H I J K L M
O   O P Q R S T U V W X Y Z A B C D E F G H I J K L M N
P   P Q R S T U V W X Y Z A B C D E F G H I J K L M N O
Q   Q R S T U V W X Y Z A B C D E F G H I J K L M N O P
R   R S T U V W X Y Z A B C D E F G H I J K L M N O P Q
S   S T U V W X Y Z A B C D E F G H I J K L M N O P Q R
T   T U V W X Y Z A B C D E F G H I J K L M N O P Q R S
U   U V W X Y Z A B C D E F G H I J K L M N O P Q R S T
V   V W X Y Z A B C D E F G H I J K L M N O P Q R S T U
W   W X Y Z A B C D E F G H I J K L M N O P Q R S T U V
X   X Y Z A B C D E F G H I J K L M N O P Q R S T U V W
Y   Y Z A B C D E F G H I J K L M N O P Q R S T U V W X
Z   Z A B C D E F G H I J K L M N O P Q R S T U V W X Y

To encipher a message, repeat the keyword above the plaintext:

FORTIFICATIONFORTIFICATIONFO
DEFENDTHEEASTWALLOFTHECASTLE

(The following assumes we are enciphering the plaintext letter D with the key letter F) Now we take the letter we will be encoding, and find the column on the tableau, in this case the 'D' column. Then, we move down the 'D' column of the tableau until we come to the key letter, in this case 'F' (The 'F' is the keyword letter for the first 'D'). Our ciphertext character is then read from the far left of the row our key character was in, i.e. with 'D' plaintext and 'F' key, our ciphertext character is 'C'.

So, the ciphertext for the above plaintext is:

FORTIFICATIONFORTIFICATIONFO
DEFENDTHEEASTWALLOFTHECASTLE
CKMPVCPVWPIWUJOGIUAPVWRIWUUK

Deciphering is performed in an identical fashion, i.e. encryption and decryption using the Beaufort Cipher uses exactly the same algorithm.

This process can be compared to the Vigenère Cipher, which uses a different algorithm, but the same tableau, for finding the ciphertext characters.

Featured Tools
Featured tools that you might find useful.

Popular Tools
List of popular tools that users love and frequently use.

New Tools
The latest tools added to our collection, designed for you.

Topics
The tools grouped by topics to quickly find what you need.

Related Tools

ROT13 Cipher is a simple letter substitution cipher with a specific key where the letters of the alphabet are offset 13 places.

ROT13 Cipher
ROT13 Cipher is a simple letter substitution cipher with a specific key where the letters of the alphabet are offset 13 places.
Simple Substitution Cipher is a cipher that has been in use for many hundreds of years. It basically consists of substituting every plaintext character for a different ciphertext character.

Simple Substitution Cipher
Simple Substitution Cipher is a cipher that has been in use for many hundreds of years. It basically consists of substituting every plaintext character for a different ciphertext character.
Running Key Cipher is a type of polyalphabetic substitution cipher in which a text, typically from a book, is used to provide a very long keystream.

Running Key Cipher
Running Key Cipher is a type of polyalphabetic substitution cipher in which a text, typically from a book, is used to provide a very long keystream.
Straddle Checkerboard Cipher is a substitution cipher, except that the substitutions are of variable length. It has formed a component of several impotant field ciphers, the most notable being the VIC cipher used by russian spies during the cold war.

Straddle Checkerboard Cipher
Straddle Checkerboard Cipher is a substitution cipher, except that the substitutions are of variable length. It has formed a component of several impotant field ciphers, the most notable being the VIC cipher used by russian spies during the cold war.