hmac_simple.py

#!/usr/bin/env python

# this is from The Python
# Standard Library by example
# ISBN13: 9780321767349

import hmac

digest_maker = hmac.new('secret-shared-key-goes-here')

with open('lorem.txt', 'rb') as f:
    while True:
        block = f.read(1024)
        if not block:
            break
        digest_maker.update(block)

digest = digest_maker.hexdigest()
print digest