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I need a zip file (ZIP64) for a test case, I put a bigfile of 5GB full of zeros and zipped it, but I don't know if is ZIP64.

Should the ZIP file exceed 4Gb to be ZIP64? A 4Gb file for a test case is pretty twisted can I have another option?

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  • Are you just after some way to confirm that the zip you create is actually a 64bit instead of a 32bit zip? – Dave Sep 11 '12 at 13:05
  • @DaveRook yes but I think they are not called 64bit and 32bit, just orginal zip format and ZIP64. – Eduard Florinescu Sep 11 '12 at 13:42
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    Googling matched this python3 script. It worked for me. – gman Sep 23 '19 at 17:51
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Download the DotNetZip devkit from http://dotnetzip.codeplex.com/. Extract the Tools folder from the dev kit and run DotNetZip-WinFormsTool.exe

It has a ZIP64 setting with the options:

  • Always
  • AsNecessary
  • Never

Select the Always option to create archives in the ZIP64 format even if they only contain small files. The interface is a little clunky, but it's workable; it allowed me to create the ZIP64 test cases I needed.

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The archival tool 7zip supports zip64 archives. You could use that to generate your test case or validate it.

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  • 7-zip.org/history.txt - 7-Zip now supports Zip64 extension of ZIP format. So now it's possible to compress files bigger than 4 GB to ZIP archives. - 'zip' is just the container, 'deflate64' is the actual compression scheme used by a zip64 file. – PhonicUK Sep 11 '12 at 9:50
  • 7zip supports deflate64 and also zip64. – Eduard Florinescu Sep 11 '12 at 9:51
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    I don't find a way to test if a zip64 with 7zip – Eduard Florinescu Sep 11 '12 at 9:53
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    I was able to determine if my Zip was Zip64 in 7-Zip by looking at the Characteristics column of the zip entries: i.stack.imgur.com/Cb6ZX.jpg – Sal Aug 21 '18 at 14:01
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The default zip(3.0) command in linux can be used to create a zip64 file. The following command on a sample HelloWorld.docx file stored in the current working directory would create a zip64 file.

cat HelloWorld.docx | zip > zip64file.zip

Here is the output of running the file command on the created file

zip64file.zip: Zip archive data, at least v4.5 to extract

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  • How would I know that it's indeed a ZIP64 file that was created? Is the file message specific for ZIP64 files? – gronostaj Mar 9 at 13:19
  • @gronostaj The file command is not specific for zip64 files. That can be used on any filetype to determine what it is based on certain signature checks. A zip64 file can be verified by looking at the raw bytes(0x12-0x16). The value would be 0xffffffff. Here is the link to where I got the information from users.cs.jmu.edu/buchhofp/forensics/formats/pkzip.html – Pete Mar 9 at 14:26
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    As documented on the man page: "Zip64 is also used for archives streamed from standard input as the size of such archives are not known in advance" – rdvdijk Mar 11 at 15:44

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