# 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 annotations import typing from cryptography.hazmat.primitives import constant_time from cryptography.hazmat.primitives.twofactor import InvalidToken from cryptography.hazmat.primitives.twofactor.hotp import ( HOTP, HOTPHashTypes, _generate_uri, ) class TOTP: def __init__( self, key: bytes, length: int, algorithm: HOTPHashTypes, time_step: int, backend: typing.Any = None, enforce_key_length: bool = True, ): self._time_step = time_step self._hotp = HOTP( key, length, algorithm, enforce_key_length=enforce_key_length ) def generate(self, time: typing.Union[int, float]) -> bytes: counter = int(time / self._time_step) return self._hotp.generate(counter) def verify(self, totp: bytes, time: int) -> None: 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: str, issuer: typing.Optional[str] ) -> str: return _generate_uri( self._hotp, "totp", account_name, issuer, [("period", int(self._time_step))], )