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ZipFile - That compression method is not supported #132223

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alex-bork opened this issue Apr 7, 2025 · 4 comments
Closed

ZipFile - That compression method is not supported #132223

alex-bork opened this issue Apr 7, 2025 · 4 comments
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stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@alex-bork
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alex-bork commented Apr 7, 2025 •
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Bug report

Bug description:

Hi, when I try to read a zipfile that has compression = 0, I get everytime the error "That compression method is not supported". In the debugger, the compression is set to 99 instead of take the one from the file itself.

I have found the code block where it is set to 99. But first my coding:

            with zip.ZipFile(io.BytesIO(zip2load.read()), mode="r") as zipfile:
                files = zip.ZipFile.namelist(zipfile)
                append_files = []
                for file in files:
                    name, ext = os.path.splitext(file)
                    try:
                        file_bytes = zipfile.read(file, pwd=password if password else None)
                    except Exception as ex:

CPython versions tested on:

3.13

Operating systems tested on:

macOS
@alex-bork alex-bork added the type-bug An unexpected behavior, bug, or error label Apr 7, 2025
@alex-bork
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Here is the code that changes the compression to 99:

Image

@picnixz picnixz added the stdlib Python modules in the Lib dir label Apr 7, 2025
@serhiy-storchaka
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99 is AE-x encryption marker (see https://pkwaredownloads.blob.core.windows.net/pem/APPNOTE.txt).

The zipfile module only supports a subset of the ZIP file format. Use other tools to unpack that file.

@StanFromIreland
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This issue can be closed, unless there's a plan to extend zipfile to support AE-x encryption (which is unlikely IMO).

@serhiy-storchaka
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If someone provides code to support strong encryption in ZIP files, we can consider it. Until then, there is no point in leaving the issue open.

@serhiy-storchaka serhiy-storchaka closed this as not planned Won't fix, can't repro, duplicate, stale Apr 8, 2025
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Labels
stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error
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Zipfile issues
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@serhiy-storchaka @picnixz @StanFromIreland @alex-bork