ROT13 / Caesar Cipher
Encrypt and decrypt text using the Caesar cipher with an adjustable shift amount. Includes ROT13 quick button and brute-force display of all 26 rotations.
How to Use the Caesar Cipher Tool
- Select Encrypt or Decrypt mode using the tabs.
- Enter your text in the input field.
- Adjust the shift amount using the slider (0-25) or click ROT13 for a shift of 13.
- The result appears instantly below the input.
- Click 'Show All 26 Rotations' to see the brute-force output for cryptanalysis.
About Caesar Cipher / ROT13
The Caesar cipher is one of the oldest known encryption techniques, named after Julius Caesar who used it in private correspondence. It works by shifting each letter in the plaintext by a fixed number of positions in the alphabet. ROT13 is a special case where the shift is 13, making it its own inverse (encoding and decoding use the same operation). While trivially breakable with modern methods, Caesar ciphers appear frequently in CTF challenges, puzzle games, and as educational tools for understanding classical cryptography.
Frequently Asked Questions
No, it is extremely insecure. With only 25 possible keys, it can be broken instantly by trying all rotations (brute force). It should only be used for educational purposes or trivial obfuscation, never for real security.
ROT13 is a Caesar cipher with a shift of 13. Because the English alphabet has 26 letters, applying ROT13 twice returns the original text. It is commonly used on the internet to hide spoilers or puzzle answers.