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.

Plaintext

Keyword

Alphabet

Enter a keyword to derive a custom alphabet, or leave blank for A–Z.

Cipher mode

Ciphertext

Tabula Recta

The cipher uses this table for encipherment. Updates when alphabet changes.