Beaufort cipher

The Beaufort cipher, created by Sir Francis Beaufort, is a substitution cipher similar to the Vigenère cipher, with a slightly modified enciphering mechanism and tableau.^[1] Its most famous application was in a rotor-based cipher machine, the Hagelin M-209.^[2] The Beaufort cipher is based on the Beaufort square which is essentially the same as a Vigenère square but in reverse order starting with the letter "Z" in the first row,^[3] where the first row and the last column serve the same purpose.^[4]

^ Franksen, Ole Immanuel, Babbage and cryptography. Or, the mystery of Admiral Beaufort's cipher. Mathematics and Computers in Simulation 35 (1993) 327-367
^ Mollin, Richard A., An Introduction to Cryptography, page 100. Chapman & Hall/CRC, 2001
^ Jörg Rothe (2006). Complexity Theory and Cryptology: An Introduction to Cryptocomplexity. Springer Science & Business Media. p. 164. ISBN 9783540285205.
^ Arto Salomaa (2013). Public-Key Cryptography: Volume 23 of Monographs in Theoretical Computer Science. An EATCS Series. Springer Science & Business Media. p. 31. ISBN 9783662026274.

[1] Franksen, Ole Immanuel, Babbage and cryptography. Or, the mystery of Admiral Beaufort's cipher. Mathematics and Computers in Simulation 35 (1993) 327-367

[2] Mollin, Richard A., An Introduction to Cryptography, page 100. Chapman & Hall/CRC, 2001

[3] Jörg Rothe (2006). Complexity Theory and Cryptology: An Introduction to Cryptocomplexity. Springer Science & Business Media. p. 164. ISBN 9783540285205.

[4] Arto Salomaa (2013). Public-Key Cryptography: Volume 23 of Monographs in Theoretical Computer Science. An EATCS Series. Springer Science & Business Media. p. 31. ISBN 9783662026274.

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