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Diffstat (limited to '.venv/lib/python3.12/site-packages/cryptography/fernet.py')
| -rw-r--r-- | .venv/lib/python3.12/site-packages/cryptography/fernet.py | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/cryptography/fernet.py b/.venv/lib/python3.12/site-packages/cryptography/fernet.py new file mode 100644 index 00000000..868ecb27 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/cryptography/fernet.py @@ -0,0 +1,223 @@ +# 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 base64 +import binascii +import os +import time +import typing + +from cryptography import utils +from cryptography.exceptions import InvalidSignature +from cryptography.hazmat.primitives import hashes, padding +from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes +from cryptography.hazmat.primitives.hmac import HMAC + + +class InvalidToken(Exception): + pass + + +_MAX_CLOCK_SKEW = 60 + + +class Fernet: + def __init__( + self, + key: bytes | str, + backend: typing.Any = None, + ) -> None: + try: + key = base64.urlsafe_b64decode(key) + except binascii.Error as exc: + raise ValueError( + "Fernet key must be 32 url-safe base64-encoded bytes." + ) from exc + if len(key) != 32: + raise ValueError( + "Fernet key must be 32 url-safe base64-encoded bytes." + ) + + self._signing_key = key[:16] + self._encryption_key = key[16:] + + @classmethod + def generate_key(cls) -> bytes: + return base64.urlsafe_b64encode(os.urandom(32)) + + def encrypt(self, data: bytes) -> bytes: + return self.encrypt_at_time(data, int(time.time())) + + def encrypt_at_time(self, data: bytes, current_time: int) -> bytes: + iv = os.urandom(16) + return self._encrypt_from_parts(data, current_time, iv) + + def _encrypt_from_parts( + self, data: bytes, current_time: int, iv: bytes + ) -> bytes: + utils._check_bytes("data", data) + + padder = padding.PKCS7(algorithms.AES.block_size).padder() + padded_data = padder.update(data) + padder.finalize() + encryptor = Cipher( + algorithms.AES(self._encryption_key), + modes.CBC(iv), + ).encryptor() + ciphertext = encryptor.update(padded_data) + encryptor.finalize() + + basic_parts = ( + b"\x80" + + current_time.to_bytes(length=8, byteorder="big") + + iv + + ciphertext + ) + + h = HMAC(self._signing_key, hashes.SHA256()) + h.update(basic_parts) + hmac = h.finalize() + return base64.urlsafe_b64encode(basic_parts + hmac) + + def decrypt(self, token: bytes | str, ttl: int | None = None) -> bytes: + timestamp, data = Fernet._get_unverified_token_data(token) + if ttl is None: + time_info = None + else: + time_info = (ttl, int(time.time())) + return self._decrypt_data(data, timestamp, time_info) + + def decrypt_at_time( + self, token: bytes | str, ttl: int, current_time: int + ) -> bytes: + if ttl is None: + raise ValueError( + "decrypt_at_time() can only be used with a non-None ttl" + ) + timestamp, data = Fernet._get_unverified_token_data(token) + return self._decrypt_data(data, timestamp, (ttl, current_time)) + + def extract_timestamp(self, token: bytes | str) -> int: + timestamp, data = Fernet._get_unverified_token_data(token) + # Verify the token was not tampered with. + self._verify_signature(data) + return timestamp + + @staticmethod + def _get_unverified_token_data(token: bytes | str) -> tuple[int, bytes]: + if not isinstance(token, (str, bytes)): + raise TypeError("token must be bytes or str") + + try: + data = base64.urlsafe_b64decode(token) + except (TypeError, binascii.Error): + raise InvalidToken + + if not data or data[0] != 0x80: + raise InvalidToken + + if len(data) < 9: + raise InvalidToken + + timestamp = int.from_bytes(data[1:9], byteorder="big") + return timestamp, data + + def _verify_signature(self, data: bytes) -> None: + h = HMAC(self._signing_key, hashes.SHA256()) + h.update(data[:-32]) + try: + h.verify(data[-32:]) + except InvalidSignature: + raise InvalidToken + + def _decrypt_data( + self, + data: bytes, + timestamp: int, + time_info: tuple[int, int] | None, + ) -> bytes: + if time_info is not None: + ttl, current_time = time_info + if timestamp + ttl < current_time: + raise InvalidToken + + if current_time + _MAX_CLOCK_SKEW < timestamp: + raise InvalidToken + + self._verify_signature(data) + + iv = data[9:25] + ciphertext = data[25:-32] + decryptor = Cipher( + algorithms.AES(self._encryption_key), modes.CBC(iv) + ).decryptor() + plaintext_padded = decryptor.update(ciphertext) + try: + plaintext_padded += decryptor.finalize() + except ValueError: + raise InvalidToken + unpadder = padding.PKCS7(algorithms.AES.block_size).unpadder() + + unpadded = unpadder.update(plaintext_padded) + try: + unpadded += unpadder.finalize() + except ValueError: + raise InvalidToken + return unpadded + + +class MultiFernet: + def __init__(self, fernets: typing.Iterable[Fernet]): + fernets = list(fernets) + if not fernets: + raise ValueError( + "MultiFernet requires at least one Fernet instance" + ) + self._fernets = fernets + + def encrypt(self, msg: bytes) -> bytes: + return self.encrypt_at_time(msg, int(time.time())) + + def encrypt_at_time(self, msg: bytes, current_time: int) -> bytes: + return self._fernets[0].encrypt_at_time(msg, current_time) + + def rotate(self, msg: bytes | str) -> bytes: + timestamp, data = Fernet._get_unverified_token_data(msg) + for f in self._fernets: + try: + p = f._decrypt_data(data, timestamp, None) + break + except InvalidToken: + pass + else: + raise InvalidToken + + iv = os.urandom(16) + return self._fernets[0]._encrypt_from_parts(p, timestamp, iv) + + def decrypt(self, msg: bytes | str, ttl: int | None = None) -> bytes: + for f in self._fernets: + try: + return f.decrypt(msg, ttl) + except InvalidToken: + pass + raise InvalidToken + + def decrypt_at_time( + self, msg: bytes | str, ttl: int, current_time: int + ) -> bytes: + for f in self._fernets: + try: + return f.decrypt_at_time(msg, ttl, current_time) + except InvalidToken: + pass + raise InvalidToken + + def extract_timestamp(self, msg: bytes | str) -> int: + for f in self._fernets: + try: + return f.extract_timestamp(msg) + except InvalidToken: + pass + raise InvalidToken |