I don’t think it’s this simple: you can still produce observable differentials with a single parser by using different options within that parser in different places. The ZIP format itself affords ample opportunities for that.

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hinkley 2 days ago | parent [-]

The settings are at encode time. For two readers the results should be unambiguous.

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woodruffw 2 days ago | parent [-]

There are plenty of decode-time knobs, even within a single ZIP parser. Here are just a few you could set while using libzip[1].

[1]: https://libzip.org/documentation/zip_open.html#DESCRIPTION

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hinkley 2 days ago | parent [-]

That’s not a lot of settings, and that’s libzib, which is not zlib.

	▲	woodruffw 2 days ago \| parent [-]
		Differentials are oracular; you only need one bit. And I’m not claiming it’s in zlib, since zlib isn’t a ZIP library. TFA here is about ZIP differentials, not differentials in DEFLATE stream parsers.