Bacon Cipher: Encrypt and Decrypt Online

in "Ciphers"

Bacon’s cipher or the Baconian cipher is a method of steganography (a method of hiding a secret message as opposed to just a cipher) invented by Francis Bacon in 1605.

A message is concealed in the presentation of text, rather than its content.

The Bacon cipher is a substitution cipher in which each letter is replaced by a sequence of 5 characters.

In the original cipher, these were sequences of A’s and B’s.

For example, the letter D was replaced by AAABB, the letter O was replaced by ABBAB and so on.

Each letter is assigned to a string of five binary digits. These could be the letters A and B, the numbers 0 and 1 or whatever else you may prefer.

Types of Bacon Cipher

First, the 24-letter cipher: In which 2 pairs of letters (I, J) and (U, V) have same ciphertexts.

Letter

Bacon Code

Binary Code

A

AAAAA

00000

B

AAAAB

00001

C

AAABA

00010

D

AAABB

00011

E

AABAA

00100

F

AABAB

00101

G

AABBA

00110

H

AABBB

00111

I, J

ABBBB

01000

K

ABAAB

01001

L

ABBAB

01010

M

ABABB

01011

N

ABBAA

01100

O

ABBAB

01101

P

ABBBA

01110

Q

ABBBB

01111

R

BAAAA

10000

S

BAAAB

10001

T

BAABA

10010

U, V

BAABB

10011

W

BABAA

10100

X

BABAB

10101

Y

BABBA

10110

Z

BABBB

10111

 

Second, the 26-letter cipher: In which all letters have unique ciphertexts.

Letter

Bacon Code

Binary Code

A

AAAAA

00000

B

AAAAB

00001

C

AAABA

00010

D

AAABB

00011

E

AABAA

00100

F

AABAB

00101

G

AABBA

00110

H

AABBB

00111

I

ABAAA

01000

J

ABAAB

01001

K

ABABA

01010

L

ABABB

01011

M

ABBAA

01100

N

ABBAB

01101

O

ABBBA

01110

P

ABBBB

01111

Q

BAAAA

10000

R

BAAAB

10001

S

BAABA

10010

T

BAABB

10011

U

BABAA

10100

V

BABAB

10101

W

BABBA

10110

X

BABBB

10111

Y

BBAAA

11000

Z

BBAAB

11001

 

Example

How to encrypt using the Bacon cipher

To encode the message, “Attack now”, we replace each letter. In this example we are using the 24-letter cipher variant.

Plaintext Letter

Baconian Ciphertext

A

AAAAA

T

BAABA

T

BAABA

A

AAAAA

C

AAABA

K

ABAAB

N

ABBAA

O

ABBAB

W

BABAA

 

Thus, “Attack now” is encrypted as: AAAAA BAABA BAABA AAAAA AAABA ABAAB ABBAA ABBAB BABAA.

How to decrypt Bacon cipher

Baconian decryption is a substitution with the biliteral alphabet of Bacon.

Use the above Bacon cipher decoder and encoder to encrypt/decrypt simple messages.

How to recognize a Bacon ciphertext

The encoded message is a biliteral code (binary with 2 letters), and maybe spaces every 5 characters.

What are the variants of the Bacon cipher?

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

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