fxj

   import base64
   import hmac
   import struct
   import time

   def totp(key, time_step=30, digits=6, digest='sha1'):
        key = base64.b32decode(key.upper() + '=' \* ((8 - len(key)) % 8))
        counter = struct.pack('>Q', int(time.time() / time_step))
        mac = hmac.new(key, counter, digest).digest()
        offset = mac[-1] & 0x0f
        binary = struct.unpack('>L', mac[offset:offset+4])[0] & 0x7fffffff
        return str(binary)[-digits:].zfill(digits)