make hmac cli

make_hmac.py

#!/usr/bin/python
'''
A little script for generating HMACs.

    > ./make_hmac.py SECRET BODY
    HMAC

For example ...

    > ./make_hmac.py secret foo
    dzukRpPHVT1u4g9h6l0nV6mk9KRNKEGuTpW1LkzWLbQ=

'''
import sys, hashlib, base64, hmac


def make_hmac(secret, body):
    """
    Calculate the HMAC value of the given request body and secret 
    as per Shopify's documentation for Webhook requests.

    http://docs.shopify.com/api/tutorials/using-webhooks#verify-webhook

    """
    digest = hmac.new(secret, body, hashlib.sha256).digest()
    return base64.b64encode(digest)


def is_valid(HMAC, secret, body):
    """
    Check if the HMAC matches that calculated from the given request
    body and secret.

    """
    return HMAC == make_hmac(secret, body)


if __name__ == '__main__':

    [secret, body] = sys.argv[1:3]
    print make_hmac(secret, body)