Bacon Cipher

Bacon's cipher relies on a substitution alphabet using only two letters, usually A and B.

Each letter of the original message is encoded as a combination of five characters composed of these two symbols, according to a system called bilitera or the Baconian alphabet.

To enhance the message's stealth, this coded sequence is often concealed within the plaintext using typographical variations: different writing styles, the use of capital letters or italics, for example.

This method allows the encrypted message to be integrated in a visually discreet manner into seemingly ordinary content.

Baconian encryption uses the substitution table:

Another bacon's alphabet (₂₆) is sometimes preferred, more complete, it uses a unique code for each letter:

Baconian decryption is a substitution with Bacon alphabet.

The ciphered message is a binary code (with 2 distinct characters), and maybe spaces every 5 characters.

Typical cases of over-encryption are alternating upper-lower case letters, bold or italic letters or encoding different character fonts.

All references to Françis Bacon (the painter or the philosopher), Kevin Bacon (actor of Batman), to Novum organum, or to bacon slices (pork, larding, smoked, salted, english breakfast, eggs, etc.) are clues.

The tomb of cryptographer William Friedmans is engraved with a hidden inscription coded with Bacon.

The letters A and B can be replaced by others characters, such as 0 and 1, to transform the message into binary format.

Sometimes the letters o and l are used: lolol loolo lolol.

The over-encryptions (of the steganographic type) are sometimes used to mask the binary form (upper case, lower case, variant characters or fonts, etc.).

The use of groups of 5 characters may be an indication of a Baconian cipher.

Francis Bacon first described the Bacon alphabet in 1605 in a letter entitled The Proficience and Advancement of Learning Divine and Humane.