buttcrack. Cipher Wiki

Bacon cipher

From the Buttcrack Cipher Wiki — the free field guide to classical ciphers

Bacon cipher — Five binary symbols per letter, so any two distinguishable things — two typefaces, two letters, upright and italic — can carry a message.

Five symbols per letter over a two-letter alphabet. Both the 24-letter (I=J, U=V) and 26-letter tables are tried.

A worked example§

Encrypting a sample with the cipher itself, at build time:

MEET ME BY THE OLD CLOCK TOWER AT DAWN

No key — the transformation is fixed.

produces the ciphertext

ababb aabaa aabaa baaba ababb aabaa aaaab babba baaba aabbb aabaa abbab ababa aaabb aaaba ababa abbab aaaba abaab baaba abbab babaa aabaa baaaa aaaaa baaba aaabb aaaaa babaa abbaa

This example is generated by running the cipher when the page is built, and the round trip is checked, so it always matches what the solver does.

How it is broken§

Find the two symbols and read off groups of five.

History and context§

Francis Bacon, 1605: not merely a cipher but the first clear statement that five bits suffice for an alphabet, three centuries before anyone wrote 'bit'.

See also§

Morse code · Bacon (letter case) · A1Z26 (numbered alphabet) · Polybius square · Tap code · NATO phonetic alphabet

Browse every cipher in the Codes and alphabets family, read the history of codebreaking, or return to the wiki main page.

Frequently asked questions§

How is the Bacon cipher broken?

Find the two symbols and read off groups of five.

What key does the Bacon cipher use?

none. There are 2 possible keys.

How much ciphertext do I need?

At least 10 characters for this solver to attempt it; short messages can be readable and still not be proof.

Can I break a Bacon cipher on this page?

Not with the browser build, which targets the common puzzle families. The desktop version searches it: see the Windows app page.

Categories: Codes and alphabets | Full-version ciphers | Cipher wiki
The facts in this article are generated from buttcrack's cipher registry when the site is built, so they describe the implementation you can run on this page. Registry-generated content is checked against the code; the history is editorial.

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What this browser solver can—and cannot—do

It tries: Caesar, Atbash, ROT13, affine, Trithemius, rail fence, single-byte XOR, periodic Vigenère-family ciphers, autokey, selected encoding layers (such as Base64, hex, binary, decimal ASCII, Morse, and reverse), and—only with 60+ A–Z letters—statistical substitution.

It does not: prove a decryption, cover every classical cipher, or break modern encryption such as AES or RSA. Its ranking model is tuned for English, so a high score is a lead to verify with the method, key, and source context—not a guarantee.

Short text, non-English plaintext, non-Latin or symbol alphabets, missing keys, and unsupported formats can all leave no high-confidence answer. When that happens, the result includes input-specific observations and suggested next checks; those observations are not a claim to know the exact cause.

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