Vigenère Cipher
Encrypt a message with a keyword, then decrypt it again.
✅ Decrypted message matches the original.
Crack it
Paste a Vigenère ciphertext. The app guesses the key length (index of coincidence + Kasiski), then each key letter (English letter frequencies), without being told the key. Works best with 200+ letters.
- Guessed key length
- Recovered key
| Key length | Average column IoC |
|---|