[FilimoniC]

http://codeazur.com.br/lab/fzip/

Note: In order to be able to decompress compressed files in a ZIP archive, FZip requires the presence of an Adler32 checksum in addition to the standard CRC32 checksums contained in ZIP archives. We provide a Python script that unobtrusively injects Adler32 checksums into ZIP archives. It is included in the FZip distribution under the 'tools' directory. This is not required if the files in the ZIP archive are stored uncompressed (formats such as GIF, JPEG, PNG or SWF for example are already compressed and do not need to be recompressed).