Vigenère Cipher
Encrypt and decrypt text using the Vigenère cipher, locally in your browser.
🔒 Your data is processed locally in your browser and is never uploaded to our servers.
How it works
The Vigenère cipher uses a keyword to apply different Caesar shifts to successive letters of the message. Each letter of the key determines the shift applied to the corresponding letter of the text.
Examples
With the text ATTACKATDAWN and the key LEMON, the encrypted result is LXFOPVEFRNHR.
Security notes
The Vigenère cipher is a classical cipher intended mainly for educational purposes. It should not be used to protect sensitive or confidential information against modern attacks.
FAQ
What can I use as a key?
Use letters from A to Z. Spaces, numbers and punctuation in the key are ignored.
Are spaces and punctuation preserved?
Yes. Only alphabetic characters in the message are encrypted or decrypted. Spaces, numbers and punctuation remain unchanged.
Does the key advance over spaces?
No. The key advances only when an alphabetic character is processed.
Is the Vigenère cipher secure?
No. It is a historical cipher and is not suitable for modern security applications.