Modern Python Standard Library Cookbook

How to do it...

Within hashlib, there are multiple supported hashing algorithms, and probably the most widespread one is md5, so we can rely on hashlib to verify our downloaded file:

import hashlib

def verify_file(filepath, expectedhash, hashtype='md5'):
    with open(filepath, 'rb') as f:
        try:
            filehash = getattr(hashlib, hashtype)()
        except AttributeError:
            raise ValueError(
                'Unsupported hashing type %s' % hashtype
            ) from None

        while True:
            data = f.read(4096)
            if not data:
                break
            filehash.update(data)

    return filehash.hexdigest() == expectedhash

Our file can then be downloaded and verified with verify_file.

For example, I might download the wrapt distribution from the Python Package Index (PyPI) and I might want to verify that it was correctly downloaded. ...