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https://gitlab.sectorq.eu/jaydee/omv_backup.git
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added v3
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223
venv/lib/python3.11/site-packages/cryptography/fernet.py
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223
venv/lib/python3.11/site-packages/cryptography/fernet.py
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# 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 binascii
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import os
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import time
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import typing
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from cryptography import utils
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from cryptography.exceptions import InvalidSignature
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from cryptography.hazmat.primitives import hashes, padding
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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from cryptography.hazmat.primitives.hmac import HMAC
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class InvalidToken(Exception):
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pass
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_MAX_CLOCK_SKEW = 60
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class Fernet:
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def __init__(
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self,
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key: bytes | str,
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backend: typing.Any = None,
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) -> None:
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try:
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key = base64.urlsafe_b64decode(key)
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except binascii.Error as exc:
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raise ValueError(
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"Fernet key must be 32 url-safe base64-encoded bytes."
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) from exc
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if len(key) != 32:
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raise ValueError(
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"Fernet key must be 32 url-safe base64-encoded bytes."
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)
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self._signing_key = key[:16]
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self._encryption_key = key[16:]
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@classmethod
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def generate_key(cls) -> bytes:
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return base64.urlsafe_b64encode(os.urandom(32))
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def encrypt(self, data: bytes) -> bytes:
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return self.encrypt_at_time(data, int(time.time()))
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def encrypt_at_time(self, data: bytes, current_time: int) -> bytes:
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iv = os.urandom(16)
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return self._encrypt_from_parts(data, current_time, iv)
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def _encrypt_from_parts(
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self, data: bytes, current_time: int, iv: bytes
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) -> bytes:
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utils._check_bytes("data", data)
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padder = padding.PKCS7(algorithms.AES.block_size).padder()
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padded_data = padder.update(data) + padder.finalize()
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encryptor = Cipher(
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algorithms.AES(self._encryption_key),
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modes.CBC(iv),
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).encryptor()
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ciphertext = encryptor.update(padded_data) + encryptor.finalize()
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basic_parts = (
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b"\x80"
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+ current_time.to_bytes(length=8, byteorder="big")
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+ iv
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+ ciphertext
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)
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h = HMAC(self._signing_key, hashes.SHA256())
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h.update(basic_parts)
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hmac = h.finalize()
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return base64.urlsafe_b64encode(basic_parts + hmac)
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def decrypt(self, token: bytes | str, ttl: int | None = None) -> bytes:
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timestamp, data = Fernet._get_unverified_token_data(token)
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if ttl is None:
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time_info = None
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else:
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time_info = (ttl, int(time.time()))
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return self._decrypt_data(data, timestamp, time_info)
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def decrypt_at_time(
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self, token: bytes | str, ttl: int, current_time: int
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) -> bytes:
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if ttl is None:
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raise ValueError(
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"decrypt_at_time() can only be used with a non-None ttl"
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)
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timestamp, data = Fernet._get_unverified_token_data(token)
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return self._decrypt_data(data, timestamp, (ttl, current_time))
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def extract_timestamp(self, token: bytes | str) -> int:
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timestamp, data = Fernet._get_unverified_token_data(token)
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# Verify the token was not tampered with.
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self._verify_signature(data)
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return timestamp
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@staticmethod
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def _get_unverified_token_data(token: bytes | str) -> tuple[int, bytes]:
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if not isinstance(token, (str, bytes)):
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raise TypeError("token must be bytes or str")
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try:
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data = base64.urlsafe_b64decode(token)
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except (TypeError, binascii.Error):
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raise InvalidToken
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if not data or data[0] != 0x80:
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raise InvalidToken
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if len(data) < 9:
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raise InvalidToken
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timestamp = int.from_bytes(data[1:9], byteorder="big")
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return timestamp, data
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def _verify_signature(self, data: bytes) -> None:
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h = HMAC(self._signing_key, hashes.SHA256())
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h.update(data[:-32])
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try:
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h.verify(data[-32:])
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except InvalidSignature:
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raise InvalidToken
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def _decrypt_data(
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self,
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data: bytes,
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timestamp: int,
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time_info: tuple[int, int] | None,
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) -> bytes:
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if time_info is not None:
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ttl, current_time = time_info
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if timestamp + ttl < current_time:
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raise InvalidToken
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if current_time + _MAX_CLOCK_SKEW < timestamp:
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raise InvalidToken
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self._verify_signature(data)
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iv = data[9:25]
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ciphertext = data[25:-32]
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decryptor = Cipher(
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algorithms.AES(self._encryption_key), modes.CBC(iv)
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).decryptor()
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plaintext_padded = decryptor.update(ciphertext)
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try:
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plaintext_padded += decryptor.finalize()
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except ValueError:
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raise InvalidToken
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unpadder = padding.PKCS7(algorithms.AES.block_size).unpadder()
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unpadded = unpadder.update(plaintext_padded)
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try:
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unpadded += unpadder.finalize()
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except ValueError:
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raise InvalidToken
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return unpadded
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class MultiFernet:
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def __init__(self, fernets: typing.Iterable[Fernet]):
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fernets = list(fernets)
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if not fernets:
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raise ValueError(
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"MultiFernet requires at least one Fernet instance"
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)
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self._fernets = fernets
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def encrypt(self, msg: bytes) -> bytes:
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return self.encrypt_at_time(msg, int(time.time()))
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def encrypt_at_time(self, msg: bytes, current_time: int) -> bytes:
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return self._fernets[0].encrypt_at_time(msg, current_time)
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def rotate(self, msg: bytes | str) -> bytes:
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timestamp, data = Fernet._get_unverified_token_data(msg)
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for f in self._fernets:
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try:
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p = f._decrypt_data(data, timestamp, None)
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break
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except InvalidToken:
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pass
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else:
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raise InvalidToken
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iv = os.urandom(16)
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return self._fernets[0]._encrypt_from_parts(p, timestamp, iv)
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def decrypt(self, msg: bytes | str, ttl: int | None = None) -> bytes:
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for f in self._fernets:
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try:
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return f.decrypt(msg, ttl)
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except InvalidToken:
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pass
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raise InvalidToken
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def decrypt_at_time(
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self, msg: bytes | str, ttl: int, current_time: int
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) -> bytes:
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for f in self._fernets:
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try:
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return f.decrypt_at_time(msg, ttl, current_time)
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except InvalidToken:
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pass
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raise InvalidToken
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def extract_timestamp(self, msg: bytes | str) -> int:
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for f in self._fernets:
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try:
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return f.extract_timestamp(msg)
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except InvalidToken:
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pass
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raise InvalidToken
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