Caesar Cipher
Shift the whole alphabet to encrypt or decrypt, 1 to 25, keeping case, with non-letters kept or blanked.
How to Use
- Set the shift and direction
1 to 25; encrypt moves letters forward, decrypt moves them back, and negatives work too (-3 equals 23).
- Decide about non-letters
Keep them as they are by default (spaces, punctuation and digits untouched), or blank them to erase the shape of the original.
- Read the result
The stat line says how many letters were processed; a non-integer shift gets a clear message instead of a silent wrong answer.
FAQ
Why does a shift of 26 encrypt nothing?
The 26-letter alphabet wraps around completely, so 0 and 26 give the same result — only 1 to 25 are meaningful. The tool also accepts negatives, where -3 is the same as 23.
Can a Caesar cipher be cracked?
Yes, and no mathematics is needed: try all 25 shifts and the readable one jumps out. Add letter frequency analysis (e is common in English, a n i in Chinese pinyin) and automated cracking takes milliseconds.
Does encrypting only letters leave clues?
It does. Word lengths, punctuation positions and spacing are all preserved, and those structural patterns give more away than the letters themselves. The option to blank non-letters exists for that reason, but it only smooths the shape slightly and is not real protection.
How is it different from the Vigenère cipher?
Vigenère cycles through several different shifts, one per letter, which makes it a polyalphabetic substitution. The Caesar cipher has a single fixed key — the simplest member of that family. The multi-alphabet version is harder to break but still a classical cipher.