Quick Py2/Py3 TOTP Generator

2fa.py

from __future__ import print_function, division, unicode_literals
import sys, time, re, struct, base64, hmac, hashlib
def get_hotp(secret, counter):
    """Return the HMAC-Based One-Time Password for the the given secret (base32 encoded) and the counter.
    >>> [get_hotp('GEZDGNBVGY3TQOJQGEZDGNBVGY3TQOJQ', i) for i in xrange(10)]
    [755224, 287082, 359152, 969429, 338314, 254676, 287922, 162583, 399871, 520489]
    """
    secret = re.sub(r'\s*', '', secret)    # remove whitespace
    secret = secret.upper()  # uppercase
    if len(secret) % 8 != 0:
        secret += '=' * (8 - len(secret) % 8)  # base32 padding

    secret = base64.b32decode(secret)
    counter = struct.pack('>Q', counter)

    hash   = hmac.new(secret, counter, hashlib.sha1).digest()
    offset = ord(hash[19:20]) & 0xF

    val = (struct.unpack(">I", hash[offset:offset + 4])[0] & 0x7FFFFFFF) % 1000000
    return '{0:06d}'.format(val)
print(get_hotp(sys.argv[1], int(time.time()//30)))