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# This file is dual licensed under the terms of the Apache License, Version # 2.0, and the BSD License. See the LICENSE file in the root of this repository # for complete details. from __future__ import absolute_import, division, print_function from cryptography.exceptions import ( UnsupportedAlgorithm, _Reasons ) from cryptography.hazmat.backends.interfaces import HMACBackend from cryptography.hazmat.primitives import constant_time from cryptography.hazmat.primitives.twofactor import InvalidToken from cryptography.hazmat.primitives.twofactor.hotp import HOTP from cryptography.hazmat.primitives.twofactor.utils import _generate_uri class TOTP(object): def __init__(self, key, length, algorithm, time_step, backend, enforce_key_length=True): if not isinstance(backend, HMACBackend): raise UnsupportedAlgorithm( "Backend object does not implement HMACBackend.", _Reasons.BACKEND_MISSING_INTERFACE ) self._time_step = time_step self._hotp = HOTP(key, length, algorithm, backend, enforce_key_length) def generate(self, time): counter = int(time / self._time_step) return self._hotp.generate(counter) def verify(self, totp, time): if not constant_time.bytes_eq(self.generate(time), totp): raise InvalidToken("Supplied TOTP value does not match.") def get_provisioning_uri(self, account_name, issuer): return _generate_uri(self._hotp, "totp", account_name, issuer, [ ("period", int(self._time_step)), ])