Why five symbols per letter?

Five binary digits give 32 combinations, which covers a 24- or 26-letter alphabet. Four would give only 16 — not enough.

Why is it called steganography as well as a cipher?

Because the A and B symbols need not be visible as letters. Hidden in the typeface or case of ordinary text, the message's existence is concealed, not just its content.

Which variant should I use?

Try 26-letter first. If the plaintext reads correctly up to an I, J, U or V and then goes wrong, switch to the 24-letter version.

Baconian Cipher Decoder

Decode Bacon's biliteral cipher from groups of five A/B symbols.

live · client-sideClassical & Obfuscated Ciphersfree · no sign-up

RAW INPUT

DECODED

Output appears here as you type — decoded on your device.

Input is processed on your device. Nothing you paste is sent anywhere.

What is the Baconian Cipher Decoder?

The Baconian cipher encodes each letter as a group of five binary symbols — traditionally A and B — which can then be hidden in the typeface, case or styling of an innocuous cover text, making it a cipher and a steganographic scheme at once.

Francis Bacon described this in 1605 as a way to conceal not just a message but the fact that a message exists. Each letter becomes five A/B symbols: AAAAA is A, AAAAB is B, and so on — five binary digits giving 32 combinations, more than enough for 24 or 26 letters.

The clever part is the carrier. The A/B distinction never needs to be written as letters: it can be two typefaces, upright versus italic, uppercase versus lowercase, or two subtly different fonts in a printed page. The cover text reads as ordinary prose while carrying a hidden payload in its styling.

The classical 24-letter version merges I with J and U with V; the 26-letter version gives each its own code. If your decode comes out one letter off part-way through, you have picked the wrong variant.

Baconian Cipher Decoder at a glance

Described: 1605, Francis Bacon
Unit: 5 binary symbols per letter (A/B)
Variants: 24-letter (I=J, U=V) or full 26-letter
Carrier: Typeface, case or styling of a cover text

How to use the Baconian Cipher Decoder

1Convert your carrier into A and B symbols — one per character, by whatever distinction it uses.
2Paste the A/B string; grouping into fives happens automatically.
3Read the decoded letters and try the other variant if the text drifts.

When you would reach for it

Solving a steganography puzzle hidden in mixed-case or mixed-font text.
Decoding a Baconian challenge in a CTF or escape room.
Illustrating binary encoding of the alphabet in a teaching context.

Baconian Cipher Decoder — frequently asked questions

Last reviewed 25 July 2026 · questions or corrections: contact@decoder.tools