Bacon

History

The Bacon cipher was developed by Sir Francis Bacon (1561-1626) and uses a method of concealing a message using two distinct sets. There are many variations of the Bacon cipher and the one implemented here follows the method used by the American Cryptogram Association (ACA) which uses the alphabet to represent the a's and b's.

Description

The Bacon cipher uses the following table as replacements for each letter with I and J being combined and U and V also combined.:

A aaaaa G aabba N abbaa T baaba

B aaaab H aabbb O abbab U/V baabb

C aaaba I/J abaaa P abbba W babaa

D aaabb K abaab Q abbbb X babab

E aabaa L ababa R baaaa Y babba

F aabab M ababb S baaab Z babbb

Each letter of the plaintext is replaced with its Bacon equivalent using the above table and producing a string of a's and b's to form an interim ciphertext. To conceal the a's and b's each letter or letter pair is assigned either a or b randomly. So, for example you could have:

ABCDEFGHIKLMNOPQRSTUWXYZ

abababababababababababab

The letters a and b in the interim ciphertext are then replaced with letters in the straight alphabet to form normal words. For example to encipher THE, using the Bacon table this becomes:

T H E

baaba aabbb aabaa

BLAME CROOK WROTE

forming the final ciphertext.

Example

Key: a = ABCDEFGHIJKLM

b = NOPQRSTUVWXYZ

Plaintext: Exit signs? They’re on the way out!

Plaintext: e x i t s i g n s t

Interim Ct: aabaa babab abaaa baaba baaab abaaa aabba abbaa baaab baaba

Ciphertext: HAZED PAPER JUICE PLANE VEILS DREAM ABOVE CORAL WAIFS VALUE

h e y r e o n t h e

aabbb aabaa babba baaaa aabaa abbab abbaa baaba aabbb aabaa

FIRST FINAL PHONE TEACH LEVEL BOXES COUGH WEIRD GLOOP MIXED

w a y o u t

babaa aaaaa babba abbab baabb baaba

WANED FIELD NERVE MOVES SAINT SHAPE

Ciphertext: HAZED PAPER JUICE PLANE VEILS DREAM ABOVE CORAL WAIFS VALUE FIRST FINAL PHONE TEACH LEVEL BOXES COUGH WEIRD GLOOP MIXED WANED FIELD NERVE MOVES SAINT SHAPE

Solving

Solving method: Brute force search.

All possible solutions are tested.