forked from STI/Astroport.ONE
93 lines
2.9 KiB
Python
93 lines
2.9 KiB
Python
# This file is dual licensed under the terms of the Apache License, Version
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# 2.0, and the BSD License. See the LICENSE file in the root of this repository
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# for complete details.
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from __future__ import annotations
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import base64
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import typing
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from urllib.parse import quote, urlencode
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from cryptography.hazmat.primitives import constant_time, hmac
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from cryptography.hazmat.primitives.hashes import SHA1, SHA256, SHA512
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from cryptography.hazmat.primitives.twofactor import InvalidToken
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HOTPHashTypes = typing.Union[SHA1, SHA256, SHA512]
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def _generate_uri(
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hotp: HOTP,
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type_name: str,
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account_name: str,
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issuer: str | None,
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extra_parameters: list[tuple[str, int]],
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) -> str:
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parameters = [
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("digits", hotp._length),
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("secret", base64.b32encode(hotp._key)),
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("algorithm", hotp._algorithm.name.upper()),
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]
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if issuer is not None:
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parameters.append(("issuer", issuer))
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parameters.extend(extra_parameters)
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label = (
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f"{quote(issuer)}:{quote(account_name)}"
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if issuer
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else quote(account_name)
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)
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return f"otpauth://{type_name}/{label}?{urlencode(parameters)}"
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class HOTP:
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def __init__(
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self,
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key: bytes,
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length: int,
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algorithm: HOTPHashTypes,
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backend: typing.Any = None,
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enforce_key_length: bool = True,
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) -> None:
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if len(key) < 16 and enforce_key_length is True:
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raise ValueError("Key length has to be at least 128 bits.")
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if not isinstance(length, int):
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raise TypeError("Length parameter must be an integer type.")
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if length < 6 or length > 8:
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raise ValueError("Length of HOTP has to be between 6 and 8.")
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if not isinstance(algorithm, (SHA1, SHA256, SHA512)):
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raise TypeError("Algorithm must be SHA1, SHA256 or SHA512.")
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self._key = key
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self._length = length
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self._algorithm = algorithm
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def generate(self, counter: int) -> bytes:
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truncated_value = self._dynamic_truncate(counter)
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hotp = truncated_value % (10**self._length)
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return "{0:0{1}}".format(hotp, self._length).encode()
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def verify(self, hotp: bytes, counter: int) -> None:
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if not constant_time.bytes_eq(self.generate(counter), hotp):
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raise InvalidToken("Supplied HOTP value does not match.")
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def _dynamic_truncate(self, counter: int) -> int:
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ctx = hmac.HMAC(self._key, self._algorithm)
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ctx.update(counter.to_bytes(length=8, byteorder="big"))
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hmac_value = ctx.finalize()
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offset = hmac_value[len(hmac_value) - 1] & 0b1111
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p = hmac_value[offset : offset + 4]
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return int.from_bytes(p, byteorder="big") & 0x7FFFFFFF
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def get_provisioning_uri(
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self, account_name: str, counter: int, issuer: str | None
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) -> str:
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return _generate_uri(
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self, "hotp", account_name, issuer, [("counter", int(counter))]
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)
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