It would be determinative only if all the header fields[1] stayed identical. A change in something like file name or mod time, would change the hash of the zipp

It would be determinative only if all the header fields[1] stayed identical. A change in something like file name or mod time, would change the hash of the zipped archive without affecting the hash of the actual file. I don't think you can expect the file mod time to be identical, as it isn't preserved through many forms of file distribution. [1]https://en.wikipedia.org/wiki/Zip_(file_format)#File_headers https://en.wikipedia.org/wiki/Zip_(file_format)#File_headers