The Caesar cipher shifts each letter along the alphabet. ROT13 (a shift of 13) is its own reverse, so the same setting encodes and decodes.
Questions
Is this secure encryption?
No – it’s a puzzle cipher. Anyone can break it by trying all 25 shifts.
Caesar Cipher & ROT13
Encode or decode text with a Caesar shift cipher. ROT13 is shift 13. Includes brute-force of all 25 shifts.