Bacon's Cipher

Hide messages using Francis Bacon's binary encoding system with two-symbol representation.

Bacon Cipher

Binary encoding using A/B

Mode

Input Text

Characters: 0Words: 0

Output Text

Example Texts

Click any example to load it

Hello World

Basic example

The quick brown fox jumps over the lazy dog

Pangram

Testing 123!

Mixed content

Free Online Tool

How to Use Examples Related Tools

What Is Bacon's Cipher?

Bacon's cipher (the biliteral cipher) is a method Francis Bacon described in 1605 for hiding a message in plain sight. Each letter is encoded as a group of five symbols drawn from just two types — written here as A and B. So the letter A is AAAAA, B is AAAAB, and so on through the alphabet.

The clever part is that the two symbols do not have to be the letters A and B. They can be any two distinguishable forms — two fonts, roman and italic, uppercase and lowercase, or bold and regular. That is what makes Bacon's cipher a steganographic method: you write an ordinary-looking cover sentence and let its styling carry the hidden A/B pattern. A casual reader sees only the cover text; someone who knows the scheme reads the concealed message. This tool can output plain A/B, binary, or a steganography cover-text form.

The Baconian Alphabet (24-letter)

The classic mapping this tool uses. I/J share one code and U/V share another, which is why the original alphabet has 24 codes rather than 26:

Letter	Code	Letter	Code
A	AAAAA	N	ABBAA
B	AAAAB	O	ABBAB
C	AAABA	P	ABBBA
D	AAABB	Q	ABBBB
E	AABAA	R	BAAAA
F	AABAB	S	BAAAB
G	AABBA	T	BAABA
H	AABBB	U/V	BAABB
I/J	ABAAA	W	BABAA
K	ABAAB	X	BABAB
L	ABABA	Y	BABBA
M	ABABB	Z	BABBB

A modern 26-letter variant gives I/J and U/V their own distinct codes; switch the tool's variant if you need every letter unique.

How to Use Bacon's Cipher

Enter letters to encode and select Encode.
Read each letter as a five-symbol A/B group; the component separates every input character with a space.
Switch to Decode to extract five-character A/B groups from encoded text.
Copy the result, remembering that I/J and U/V intentionally share codes.

This is the 24-letter Baconian mapping: each alphabetic symbol is represented by five binary-like choices written as A and B.

Examples

Three letters — input:

ABC

Output:

AAAAA AAAAB AAABA

Word — input:

TEST

Output:

BAABA AABAA BAAAB BAABA

Worked Example: Hiding a Message

Take the word HIDE. Encode each letter with the chart above:

H = AABBB I = ABAAA D = AAABB E = AABAA

HIDE → AABBB ABAAA AAABB AABAA

That is the plain A/B output. To actually hide it, map every A and B onto two forms in a cover sentence — say regular for A and bold for B. Writing the first letter (AABBB) across five cover characters gives: regular, regular, bold, bold, bold. The sentence reads normally; the pattern of forms carries HIDE. Anyone reading the styling five characters at a time recovers the message.

Type HIDE into the tool above with the original variant to reproduce the A/B groups exactly.

Frequently Asked Questions

How do you hide a message with Bacon's cipher?

Encode your text to five-symbol A/B groups, then map A and B onto two visible forms in an ordinary cover sentence — two fonts, roman vs italic, or regular vs bold. The cover reads normally while its styling carries the pattern.

What is the difference between the 24 and 26-letter versions?

The original alphabet shares one code between I and J and another between U and V, giving 24 codes. The modern variant assigns all 26 letters their own distinct code. This tool supports both.

Is Bacon's cipher secure?

Not as encryption. It has no key, so once someone knows the scheme it is trivial to decode. Its strength is concealment — hiding that a message exists at all — not cryptographic secrecy. Treat it as steganography, not strong encryption.

Is it the same as binary?

It is binary-like: two symbols, five per letter (5 bits). But Bacon designed it in 1605, long before modern binary, and its point is that the two symbols can be any two distinguishable forms, not only 0 and 1.