SubstitutionDifficulty: Easy
Caesar cipher
Every letter moves a fixed number of places along the alphabet. The most famous cipher in the world and a perfect first step.
Try it
27 characters
Result · Caesar cipher
Vhfuhw phvvdjh iru wkh foxe
How it works
- 1Write the alphabet twice, one row under the other, and slide the bottom row by a chosen number of places - say 3 to the right.
- 2Find each letter of your message in the top row and write the letter below it: A becomes D, B becomes E, C becomes F.
- 3At the end of the alphabet you wrap around: X becomes A, Y becomes B and Z becomes C.
- 4To decode, slide back the other way. Don't know the shift? Try all 25 - exactly one gives readable text.
Example
Hello world
Khoor zruog
Did you know
The cipher is named after Julius Caesar. The Roman historian Suetonius wrote that Caesar kept secret messages by replacing each letter with the one three places further along the alphabet (D for A). Anyone can break it in minutes today, since there are only 25 shifts, but it is still the best way to start with ciphers.
Try to decode
This message is encrypted with Caesar cipher using the default settings:
PHHW DW WKH ROG EULGJH
Hint
The shift is 3. To decode, step three letters back: D is really A.
Show solution
MEET AT THE OLD BRIDGE
More ciphers in this category
- Vigenère cipherA Caesar cipher with a password: each letter shifts by a different amount set by the keyword. Much tougher than plain shifting.
- Polybius squareLetters in a 5x5 grid, each written as a pair of numbers: row and column. You can tap it, flash it or clap it.
- AtbashThe alphabet flipped like a mirror: A becomes Z, B becomes Y. No key, no settings, and decoding is the same as encoding.
- ROT13A Caesar cipher with a shift of 13: the same steps encode and decode. No settings, just one click.