Vigenère Cipher

Encrypt and decrypt text using the Vigenère polyalphabetic substitution cipher with a keyword

All processing happens in your browser. No data is uploaded.

Offline Ready

Vigenere Cipher

Encrypt or decrypt text using the Vigenere cipher with a keyword-based polyalphabetic substitution.

🔒All processing happens in your browser. No data is uploaded.

Encrypt

Decrypt

Keyword

Enter keyword (letters only), e.g.: SECRET

Plaintext

Enter text to encrypt...

Ciphertext

Enter a keyword first

About the Vigenere Cipher

The Vigenere cipher is a polyalphabetic substitution cipher that uses a keyword to shift each letter differently. Each letter of the keyword determines the shift amount for the corresponding plaintext letter (A=0, B=1, ..., Z=25). The keyword repeats cyclically for longer messages. Non-alphabetic characters are passed through unchanged.