ZIP unsupported compression method 99

Some password protected ZIP files, usually created with a recent WinZip (9.0 or newer), are encrypted using new method, the AES encryption.

Older utilities like unzip on Linux, old WinZip, or pkunzip does not know how to handle that, and usually just abort operation complaining that they does not support compression method 99.

To extract those ZIP files one can use:

  • recent WinZip (Windows only, €30, free trial)
  • 7z tool (Windows, Linux, Mac OS X & others, free, open source – LGPL)

The 7z can be obtained from the 7z home site, but for Linux should be easily available from the system repository.

on Fedora you can install it with:

yum install p7zip p7zip-plugins

Command line syntax for extracting the archive is:

7z x file.zip

Post Scriptum: this is an import of information that I wrote a while ago. Things might have changed since then.

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11 Responses to ZIP unsupported compression method 99

  1. Heke says:

    Thanks Jan for the tip! Saved my day.
    The most recent install line for Fedora seems to be
    # yum install p7zip p7zip-plugins
    (i.e. “s” in the end of plugin filename….)

  2. Chester says:

    Thanks for the tip. Mac users can install it using Homebrew as well:

    brew install p7zip

  3. Sean says:

    Thanks worked a treat

  4. TMD says:

    This works a treat, thanks! Under Ubuntu it’s

    sudo apt-get install p7zip-full

    and then you can either use 7z as a command line as you describe; or Gnome archive manager suddenly starts working, so you can use that.

  5. This was useful! Thank you!

  6. Windsor Schmidt says:

    On my Arch system I got the “type 99″ error using unzip, but 7z decompressed my encrypted archive. This article was a big help. Thanks!

  7. Matěj Viezan says:

    Thank you, it works!

  8. Tim says:

    So apparently even Windows 10′s zip handler can’t handle these files. It gives an unknown error. Fortunately “unzip” on Linux was more helpful with the 99, which was how I ended up here.

  9. Anonymous says:

    Got here while struggling with “method 99″ in Apple .ipa app package. It doesn’t have encrypted flag set, but file streams are marked as ’99′. If you look at raw data streams, they start with ‘bvx2′, which points to Apple LZFSE compression (Apple opensourced it, so you can get command line tool and library on Github) and indeed applying their tool unpacks the stream properly.

  10. anonamous says:

    it works like magic!

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