Auto-key Crack !exclusive! Only Instant

In a standard Vigenère, these streams are static shifts (Monoalphabetic). In Autokey, Stream $k$ is dependent on previous characters in Stream $k$.

The algorithm works as follows:

Note the vital distinction: the plaintext is encrypted using itself (shifted backward) as the key. auto-key crack only

To understand the crack, one must first understand the construction. In a standard Vigenère, these streams are static

Modern cracking tools (like the Python library pycipher or custom scripts) automate this by calculating the "Candidate Key" for every possible shift of a crib across the ciphertext. In a standard Vigenère