A ZIP archive may contain many entries whose content can be compressed
and/or encrypted. In particular, entries can be encrypted with a
password-based symmetric encryption algorithm referred to as
traditional PKWARE encryption, legacy encryption or ZipCrypto.

bkcrack is a command-line tool which implements a known plaintext
attack by Biham and Kocker. The main features are:

    Recover internal state from ciphertext and plaintext.
    Change a ZIP archive's password using the internal state.
    Recover the original password from the internal state.