Bacon Cipher (Baconian) Encoder, Decoder & Hider
Encode and decode Bacon’s cipher with the 24- or 26-letter alphabet and any two symbols, or hide a message in ordinary text using upper and lower case.
| Letter | Code |
|---|---|
| A | AAAAA |
| B | AAAAB |
| C | AAABA |
| D | AAABB |
| E | AABAA |
| F | AABAB |
| G | AABBA |
| H | AABBB |
| I | ABAAA |
| J | ABAAB |
| K | ABABA |
| L | ABABB |
| M | ABBAA |
| N | ABBAB |
| O | ABBBA |
| P | ABBBB |
| Q | BAAAA |
| R | BAAAB |
| S | BAABA |
| T | BAABB |
| U | BABAA |
| V | BABAB |
| W | BABBA |
| X | BABBB |
| Y | BBAAA |
| Z | BBAAB |
Francis Bacon devised this cipher in 1605 as a way to hide a message inside an innocent text: every letter becomes five symbols of two kinds, A and B, which can be disguised as two typefaces, upper and lower case, or any other pair of choices. This tool encodes and decodes with Bacon’s original 24-letter alphabet or the modern 26-letter version, with any two symbols, and can hide a message in a carrier sentence using letter case.
How to use this tool
- Choose encode, decode, hide or reveal.
- Type the message or paste the code; any two symbols (A/B, 0/1, ■/□) work.
- Pick the 26-letter alphabet, or the 24-letter one for historical puzzles.
- For hiding, paste a carrier text with at least five letters per message letter.
Formula
code(letter) = its index (A = 0) written as a 5-bit binary number, with A for 0 and B for 1
The 26-letter version uses indexes 0–25 (Z = BBAAB). Bacon’s 24-letter alphabet gives I and J one code (ABAAA) and U and V another (BAABB), so the letters after J and after V shift by one. When hiding, each carrier letter carries one bit: lower case = A, upper case = B.
Example
HELLO with 26 letters: H is 7 = 00111 → AABBB, E = 4 → AABAA, L = 11 → ABABB, O = 14 → ABBBA, giving AABBB AABAA ABABB ABABB ABBBA. Hiding "HI" (AABBB ABAAA) in "the weather was lovely" changes the case of the first ten letters: thE WEaTher was lovely.
Frequently asked questions
What is the difference between the 24- and 26-letter versions?
Bacon’s original alphabet had 24 letters because I/J and U/V were not yet separate letters, so they share codes. Most modern puzzles use 26 distinct codes; if a decode gives nonsense from the middle of the alphabet on, try the other version.
Can I use other symbols than A and B?
Yes. Set any two single characters, such as 0 and 1, X and Y, or emoji. Decoding ignores every other character.
Is Bacon’s cipher secure?
No. It is steganography — hiding that there is a message — not encryption. Once someone suspects two kinds of letters, the code is easy to read.
Last updated:
Page address with these inputs: https://kakao.mobile/tools/bacon-cipher-tool/
Cite or embed this tool
kakaoCalc. (2026, November 8). Bacon Cipher (Baconian) Encoder, Decoder & Hider. https://kakao.mobile/tools/bacon-cipher-tool/
“Bacon Cipher (Baconian) Encoder, Decoder & Hider.” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/bacon-cipher-tool/.
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