Beaufort Cipher decoder and encoder

The Beaufort Cipher is named after Sir Francis Beaufort. It is similar to the Vigenère, but the encryption and decryption is reciprocal (the encryption and decryption algorithms are the same). The Beaufort cipher is a polyalphabetic cipher, a series of Caesar ciphers, based on the letters of a keyword.

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Beaufort Cipher Tool

You must enter the message.
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You must enter the encryption key.
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Auto Solve Options


Instructions

You can decode (decrypt) or encode (encrypt) your message with your key. If you don't have any key, you can try to auto solve (break) your cipher.

Settings
  • Standard Mode v s Autokey Variant: The Autokey mode is a stronger variant of the cipher, where letters of the plaintext become part of the key. It eliminates the periodic repeats otherwise seen in polyalphabetic ciphers.
  • Language: The language determines the letters and statistics used for decoding, encoding and auto solving.
  • Min/Max Key Length: This is the search range for keys when auto solving a cipher.
  • Iterations: The more iterations, the more time will be spent when auto solving a cipher.
  • Max Results: This is the maximum number of results you will get from auto solving.
  • Spacing Mode: This is about the spaces (word breaks) in the text. In most cases it should be set to Automatic. In case a specific letter (for instance X) is used as word separator, set it to Substitute.

Note: Auto Solve will try in the mode you select (Standard Mode or Autokey mode). Standard mode is the most common, but if you don't know the mode, you should try both.


Not seeing the correct result? Try Auto Solve or use the Cipher Identifier Tool.


Auto Solve results

Score Key Text

Still not seeing the correct result? Then try experimenting with the Auto Solve settings or use the Cipher Identifier Tool.

Features

  • The Beaufort cipher is a polyalphabetic substitution cipher. The Enigma machine is another example of a (more complex) polyalphabetic substitution cipher.
  • It was named after Sir Francis Beaufort, an Irish officer in the Royal Navy.
  • The Beaufort cipher is reciprocal, that is, decryption and encryption algorithms are the same.
  • A Beaufort cipher works similar to the Vigenère cipher, only that instead of adding letter values, it calculates the cipherletter = keyletter - plaintextletter.
  • After applying an Atbash cipher, the Beaufort cipher can be broken using same methods as a Vigenère cipher.

Beaufort ciphers, and variants of it, are occasionally used in CTFs, geocaching mystery caches, and logic puzzles.

Sample Beaufort Cipher

Code-breaking is not only fun, but also a very good exercise for your brain and cognitive skills. Why don’t you try breaking this example cipher:

zlayv wptofsf k qym hdo slzs ij rq k byoswol lq iuhxjs zyb lw cg gp hlyd d ilkda wx jvpvru gpeyfszt clw xgj fszy jk kdm jk hzg jrv bclwfl dy ucozcqmzh