Caesar / ROT13 / Vigenère / Atbash Cipher
Text
Four classical letter-substitution ciphers in one tool. **Caesar** shifts every letter by a fixed amount (3 for the original 'Caesar's cipher'). **ROT13** is Caesar with shift 13 — its own inverse, used for spoiler tags. **Vigenère** uses a repeating keyword to vary the shift per letter (strong by hand standards, trivial today). **Atbash** mirrors the alphabet (A↔Z, B↔Y…). For Caesar, a brute-force panel shows all 26 possible decryptions at once.
How to use
- Pick a cipher and (for Caesar/Vigenère) choose encode or decode.
- Type or paste the text. For Caesar, drag the shift slider; for Vigenère, type the key.
- Output updates live. The brute-force panel below tries all 26 Caesar shifts when you're trying to crack a message.
Frequently asked questions
- Are these secure?
- No — they're educational and used in puzzles. Even Vigenère falls to frequency analysis once the key length is known. Use AES or modern ciphers for real security.
- Why is ROT13 used at all?
- Spoiler tags, joke punchlines, mild obfuscation. Because it's its own inverse, the same tool encodes and decodes.
- What characters get shifted?
- Only A-Z and a-z. Numbers, spaces, punctuation, and non-Latin scripts pass through untouched.
- How is the brute-force panel useful?
- When you know a message is Caesar-shifted but don't know the shift — scroll through all 26 outputs and pick the one that reads as plain text.
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