Toolstia / Caesar cipher
Caesar cipher
The Caesar cipher replaces each letter with the one a fixed number of places along the alphabet. Encode a message, decode one if you know the shift, or try every shift at once to crack it without the key.
The Caesar cipher moves each letter along the alphabet by the shift. Digits, spaces and punctuation are left alone. It is a historical puzzle cipher and offers no real security.
How it works
- Paste your text.
- Choose Encode, Decode or Try every shift.
- Set the shift and copy the result.
How it works
With a shift of 3, A becomes D, B becomes E and Z wraps round to C. Decoding shifts the other way. Only the letters A to Z are changed.
Cracking
There are only 25 possible shifts, so the Try every shift mode shows every possible decoding. The right one is the one that reads as normal text.
Any shift
Shifts above 25 or below 0 wrap around, so a shift of 29 equals 3.
Not secure
The Caesar cipher is a classic puzzle and teaching tool. It is easily broken and must not be used to protect anything private.
Questions
What shift did Julius Caesar use?
Historical sources say 3.
What about digits and punctuation?
They are left unchanged.
Is anything uploaded?
No. Everything is done in your browser and nothing is sent anywhere.