Vigenere Cipher
Securely encrypt and decrypt messages using a keyword. Polyalphabetic substitution made easy.
Polyalphabetic
Uses multiple substitution alphabets based on your key for stronger security than Caesar cipher.
Client-Side
Your secret keys and messages never leave your browser. 100% private.
Real-Time
See the encryption/decryption results instantly as you type your message or key.
Try These Examples
Basic Encryption
Classic Vigenere encryption example.
Decrypt Message
Decrypting the classic example back to plaintext.
Long Key
Encrypting a longer sentence with a repeating key.
Case Preservation
Shows how non-alphabetic characters are handled.
About Vigenère Cipher
The Vigenère cipher is a method of encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword. It employs a form of polyalphabetic substitution.
First described by Giovan Battista Bellaso in 1553, the cipher is easy to understand and implement, but it resisted all attempts to break it for three centuries, which earned it the description le chiffre indéchiffrable (the indecipherable cipher).
How it Works
To encrypt, a table of alphabets can be used, termed a tabula recta, Vigenère square or Vigenère table. It has the alphabet written out 26 times in different rows, each alphabet shifted cyclically to the left compared to the previous row, corresponding to the 26 possible Caesar ciphers.
At different points in the encryption process, the cipher uses a different alphabet from one of the rows. The alphabet used at each point depends on a repeating keyword.