hashlib_test.py

#!/usr/bin/env python

import hashlib


def chunked_sha1sum(filelike, chunk_size=0x100000):
    hasher = hashlib.new('sha1')

    while True:
        chunk = filelike.read(chunk_size)
        if not chunk:
            break
        hasher.update(chunk)
    
    return hasher.hexdigest()


with open('some_dvd_dump.iso', 'rb') as f:
    sha1sum = chunked_sha1sum(f)

print(sha1sum)