Vigenère Cipher Calculator

Encrypt and decrypt text using Vigenère cipher.

Cipher Settings

Secret Key

Output

Rijvs Uyvjn

About this calculator

Overview

Vigenère cipher uses keyword-based polyalphabetic substitution. More secure than Caesar cipher. Used historically for military and diplomatic communications.

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Pro Tips

Keyword repeated to match message length.
Use Vigenère square/table for encryption.
Longer keyword = more secure.
Frequency analysis harder than Caesar.

Fun Facts

"Invented 1553 by Giovan Battista Bellaso."
"Called 'le chiffre indéchiffrable' (indecipherable)."
"Broken by Charles Babbage (1854)."
"Used in American Civil War."

Formula: Cipher Letter = (Plain Letter + Key Letter) mod 26