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Baconian Cipher Decoding

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Terms you will need

  • baconian cipherA Baconian cipher is a method of hiding a secret message within the presentation of text, using two different typefaces to represent letters 'A' and 'B'.
  • a/b valuesIn a Baconian cipher, 'A' and 'B' values are used to represent letters in a secret message, with each letter of the message being replaced by a group of five 'A's or 'B's.
  • bold/italic/underlineIn a Baconian cipher, bold, italic, or underlined text can be used as different typefaces to represent 'A' or 'B' values in the hidden message.
  • plaintextPlaintext is the original message before it is encoded or encrypted.
  • ciphertextCiphertext is the result of encoding or encrypting a message, making it unreadable without decoding.
  • character renderingCharacter rendering refers to how characters are displayed or presented, such as using different typefaces in a Baconian cipher.

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The Baconian cipher is a method of steganographic message encoding devised by Francis Bacon in 1605. It conceals a secret message within the presentation of text, rather than its content. This cipher is both a substitution cipher and a concealment cipher, using two different typefaces to represent the letters 'A' and 'B'. Each letter of the plaintext is replaced by a group of five 'A's or 'B's, forming a 5-bit binary encoding. The Baconian alphabet is used to recover the original message by decoding the pattern of typefaces. This method allows a secret message to be hidden in plain sight, using any false message of the appropriate length. The Baconian cipher is an important example of early cryptographic techniques and demonstrates the concept of steganography, which is the practice of hiding messages within other non-secret text or data.

Figures (5)

Daoist Bagua
An example of a recursive binary space partitioning quadtree for a 2D index
Image of Bacon's cipher.
Gottfried Leibniz
George Boole

Instead of hiding the message in the words themselves, it hides it in how the text is presented. This is called steganography. The cipher uses two different typefaces—like regular and bold—to represent the letters 'A' and 'B'.

Each letter in the real message is turned into a group of five A's or B's. This is a 5-bit binary code, meaning each letter is represented by a pattern of five choices. The writer creates a fake message with the same number of letters as the A's and B's in the real message.

Then, each letter in the fake message is written in the correct typeface to match the A or B it stands for. Every regular letter is an A, and every bold letter is a B. These are grouped into sets of five and matched to the Baconian alphabet to find the real message.

The secret message is hidden in plain sight, making it hard to notice unless you know to look for the pattern. This method shows how early cryptographers used creativity to hide messages. It’s a mix of substitution and concealment, and it works best when the fake message looks normal and unrelated to the real one.

Key Points

  • The Baconian cipher is a method of steganographic message encoding devised by Francis Bacon in 1605, where each letter of the plaintext is replaced by a group of five of the letters 'A' or 'B'.
  • In the Baconian cipher, two different typefaces are used for encoding, and any method of writing the message that allows two distinct representations for each character can be used, such as bold, italic, or underline.
  • In the Baconian cipher, each letter of the plaintext is replaced by a group of five of the letters 'A' or 'B' according to the alphabet of the Baconian cipher.

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