auth.py 文件源码

def compute_totp(secret, offset=0):
    """
    Computes the current TOTP code.

    :param secret: Base32 encoded secret.
    :type secret: unicode
    :param offset: Time offset (in steps, use eg -1, 0, +1 for compliance with RFC6238)
        for which to compute TOTP.
    :type offset: int

    :returns: TOTP for current time (+/- offset).
    :rtype: unicode
    """
    assert(type(secret) == six.text_type)
    assert(type(offset) in six.integer_types)
    try:
        key = base64.b32decode(secret)
    except TypeError:
        raise Exception('invalid secret')
    interval = offset + int(time.time()) // 30
    msg = struct.pack('>Q', interval)
    digest = hmac.new(key, msg, hashlib.sha1).digest()
    o = 15 & (digest[19] if six.PY3 else ord(digest[19]))
    token = (struct.unpack('>I', digest[o:o + 4])[0] & 0x7fffffff) % 1000000
    return u'{0:06d}'.format(token)