About this tool
The Baconian (Bacon) Cipher Encoder / Decoder is a free, in-browser tool for Francis Bacon's biliteral cipher, invented around 1605. Every letter of the alphabet is represented by a group of five symbols drawn from just two states — traditionally A and B — so each letter becomes a pattern like AABBB. With five binary positions there are 32 possible codes, more than enough for the 26 letters, which is what makes the cipher work as a five-bit binary encoding of the alphabet.
Two tables are offered. The 24-letter classic table follows Bacon's original, in which I and J share one code and U and V share another (AAAAA for A up through BABBB for Z). The 26-letter distinct table gives every letter its own unique five-bit code from 00000 to 11001. You can display the output as A/B or as 0/1. All processing happens locally in your browser and nothing you type is sent anywhere.
When encoding, non-letters are ignored and each letter becomes a five-symbol group. When decoding, the tool strips everything except the two symbols, splits the stream into groups of five, and maps each group back to a letter. The Baconian cipher's real cleverness is steganographic: because it needs only two distinct states, the A's and B's can be hidden in a cover text using two typefaces, upper- and lower-case letters, or any other subtle two-way difference — letting a secret message hide in plain sight, which is why it is a favourite of escape rooms and puzzle hunts.