Vigenère / Autokey Cipher
Polyalphabetic substitution cipher with optional autokey extension.
The Vigenère cipher is a polyalphabetic substitution cipher that uses a keyword and an encryption table (the tabula recta) to shift each letter of the plaintext. The Autokey cipher is a stronger variation where the plaintext itself becomes part of the key, making frequency analysis much harder. This tool supports both, pick the mode below. Don't know the keyword? Use Solve automatically to crack it from ciphertext.
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Keyword case doesn't matter (CACHE = cache). The letter case of your text is preserved in the output.
Enter a keyword to derive a custom alphabet, or leave blank for A–Z.
Sets the language statistics the solver scores against. Choose Auto to detect the plaintext language from the ciphertext and switch to it automatically (needs at least ~20 letters). Raise the max keyword length for longer keys, but note that longer keys need more ciphertext to crack reliably.
Both solvers honor the selected cipher mode and custom alphabet.
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Tabula Recta
The cipher uses this table for encipherment. Updates when alphabet changes.