Caesar Cipher Decoder

Why the Caesar cipher always breaks

The Russian alphabet gives 31 possible shifts, the Latin alphabet 25. You could try them all by hand in a couple of minutes, so this tool simply runs through every shift at once: below the result there is a table with all the variants, and a click on a row expands it in full.

The version moved to the top is the one that looks most like language. The score is based on single-letter frequencies, on the share of frequent pairs such as "ст" and "но", and on recognizable words. A short phrase is enough: with 20–30 letters the correct shift is usually already visible.

ROT13 and the Latin alphabet

ROT13 is the same cipher with a shift of 13. On Latin text it has a handy property: applying it twice returns the original text. The tool picks the alphabet on its own, but you can set the language manually, because on a mix of Cyrillic and Latin letters the frequencies get skewed.

If nothing reads

The cipher is something else. Neighboring pages cover the Vigenère cipher and Atbash, and the reverse task is solved on the Caesar, Vigenère and Atbash encoders.