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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 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: 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: str | None
) -> str:
return _generate_uri(
self._hotp,
"totp",
account_name,
issuer,
[("period", int(self._time_step))],
)
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