Baconian Cipher

How it is calculated

The Baconian cipher replaces each letter with a group of five symbols, a or b. In this 26-letter version the letter's position in the alphabet counted from 0 (A = 0, B = 1 … Z = 25) is written as a 5-bit binary number, with 0 as a and 1 as b. So A = aaaaa, B = aaaab and Z = bbaab.

When encoding, the text is made uppercase, letters within a word are separated by one space and words by two spaces; digits, punctuation and accented letters are skipped. When decoding, only a and b (any case) are read, everything else is ignored, and the symbols are cut into groups of five from the start. A group whose value is above 25 is dropped, and a leftover group shorter than five is ignored. The original I/J and U/V merged variant is not used.

Common mistakes

• Counting the alphabet from 1 instead of 0. A must be aaaaa, not aaaab, or every letter shifts by one.
• Decoding text that uses the historic 24-letter table, where I/J and U/V share a code. Those messages will decode with some wrong letters here.
• Breaking the a/b string into groups of the wrong size or dropping one symbol; every later letter is then misread.
• Expecting digits or punctuation to be encoded. They are skipped, so they vanish from the message.