How to recover ZIP passwords?
Zip-archivers (pkzip, WinZip versions up to 8.0) use their own encryption algorithm which is not strong. This causes two practical vulnerabilities. Firstly, it’s always possible to implement a plain-text attack (one unencrypted file from the archive needed). Secondly, if the archive was created with WinZip (up to 8.0 version only) or Infozip and contains 5 or more files, then it is possible to decrypt the archive with guarantee regardless of password length and complexity. Both attacks take just couple of hours on the modern computer. In the latest WinZip versions there is an option that allows using strong AES algorithm. In this case the said attacks are unapplicable and only brute-force can be used. Modern ZIP password crackers should support all these attacks.