What is the Baconian Cipher?

The Baconian cipher uses a binary system of encoding the letters of the alphabet. For example, A is encoded with aaaaa, B is encoded with aaaab, and so on. This method encodes a true message in a seemingly innocuous note, where the first letters of the words in the message are converted into A or B depending on which half of the alphabet the letter appears in. Alternatively, each letter of the encoded message can represent an A or B in the encryption scheme.

Example

Letter codes

A = aaaaa E = aabaa I/J= abaaa N = abbaa R = baaaa  W = babaa
B = aaaab F = aabab K  = abaab O = abbab S = baaab  X = babab
C = aaaba G = aabba L  = ababa P = abbba T = baaba  Y = babba
D = aaabb H = aabbb M  = ababb Q = abbbb U/V= baabb Z = babbb

Plaintext: SOS

Coded Message: Take a dog for the brief walk to a store where he can get treats.

Initials:
TADFT BWTAS WHCGT
baaab abbab baaab

baaab = S
abbab = O
baaab = S

Vulnerabilities of Baconian Cipher

A message encoded with Baconian Cipher might not sound natural, which may alert a potential solver to the possibility that this method is in use. In addition, the message must have a number of words divisible by five, because each plaintext letter is encoded using five "bits," or in this case, As and Bs. If each letter in the ciphertext represents an A or B instead, it is also easy to see that the number of letters will have to be divisible by five.

How to Crack a Baconian Cipher

The hard part of solving a Baconian Cipher is merely to determine that this is the method in use. Once that is determined, it is simple to take the letters of the message and convert them into the plaintext.