Crypto Lab

Classical

Vigenere Cipher

Uses a repeated keyword to apply a different Caesar shift to each letter.

Classical

Playground

Change inputs and inspect the transformation

A polyalphabetic substitution: each key letter controls one shift.

Output

Ciphertext

VIYBR ABCNDS

Decrypted

LEARN CRYPTO

Steps

Transformation trace

  1. Keyword

    KEY => 10, 4, 24

    Each key letter becomes a Caesar shift.

  2. Encrypt

    plaintext letter + repeating key shift => VIYBR ABCNDS

    The keyword repeats across alphabetic characters.

  3. Decrypt

    cipher letter - repeating key shift => LEARN CRYPTO

    Subtracting the same repeated shifts restores the message.