import base64
import hashlib

def generate256(file):
    with open(file, 'r') as f:
        body = f.read()
        hash = hashlib.sha256(body).digest()
        sha  = base64.b64encode(hash).decode()
        return 'sha256-{}'.format(sha)

# Python 2.7.10 (default, Oct 14 2015, 16:09:02)
# [GCC 5.2.1 20151010] on linux2
# Type "help", "copyright", "credits" or "license" for more information.
# >>> from sri import generate256
# >>> generate256("sri.py")
# 'sha256-ZDTvTHvqQDypoPxKGrkYPNVeXQPvKqnZeAFvRZ1l+ik='
# >>>