Generate HMAC in Python

gen_hmac.py

import hmac, hashlib, json, time, base64

SHARED_SECRET = 'sup3rs3cr3t!!'

def signString(string_to_sign, shared_secret):
	return hmac.new(shared_secret, string_to_sign, hashlib.sha512).digest()

if __name__ == '__main__':
	payload = {
		'name': 'joe smith',
		'category': 'people',
		'action': 'transport',
		'where': 'pluto',
		'timestamp': str(int(time.time()))
	}

	json_payload = json.dumps(payload)
	signature = signString(json_payload, SHARED_SECRET)

	encoded_signature = base64.urlsafe_b64encode(signature)
	encoded_payload = base64.urlsafe_b64encode(json_payload)

	print('/?data={}&signature={}').format(encoded_payload, encoded_signature)