bitballoon_multipass.py

### pip install pycrypto

import base64
from Crypto.Cipher import AES
from Crypto import Random
import datetime
import hashlib
import hmac
import json
import os
import urllib

MULTIPASS_SECRET = os.environ['BITBALLOON_MULTIPASS_SECRET']
def generate_multipass_token(user_data):
    key = hashlib.sha256(MULTIPASS_SECRET).digest()
    encryption_key = key[:16]
    signature_key = key[16:]

    user_data['created_at'] = datetime.datetime.now().isoformat()
    user_data = json.dumps(user_data)

    BS = 16
    pad = lambda s: s + (BS - len(s) % BS) * chr(BS - len(s) % BS)

    raw = pad(user_data)
    iv = Random.new().read(AES.block_size)
    cipher = AES.new(encryption_key, AES.MODE_CBC, iv)
    cipher = iv + cipher.encrypt(raw)

    sig = hmac.new(signature_key, cipher, hashlib.sha256).digest()

    token = base64.b64encode(cipher + sig)
    return urllib.quote_plus(token)
    
    
if __name__ == '__main__':
    import time, sys
    user_email = sys.argv[-1]
    user_data = {"email": user_email, "expires": time.mktime((datetime.datetime.now() + datetime.timedelta(1)).timetuple())}
    print "?multipass_token=%s" % generate_multipass_token(user_data)