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authorS. Solomon Darnell2025-03-28 21:52:21 -0500
committerS. Solomon Darnell2025-03-28 21:52:21 -0500
commit4a52a71956a8d46fcb7294ac71734504bb09bcc2 (patch)
treeee3dc5af3b6313e921cd920906356f5d4febc4ed /.venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/ciphers/modes.py
parentcc961e04ba734dd72309fb548a2f97d67d578813 (diff)
downloadgn-ai-master.tar.gz
two version of R2R are hereHEADmaster
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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 abc
+
+from cryptography import utils
+from cryptography.exceptions import UnsupportedAlgorithm, _Reasons
+from cryptography.hazmat.primitives._cipheralgorithm import (
+ BlockCipherAlgorithm,
+ CipherAlgorithm,
+)
+from cryptography.hazmat.primitives.ciphers import algorithms
+
+
+class Mode(metaclass=abc.ABCMeta):
+ @property
+ @abc.abstractmethod
+ def name(self) -> str:
+ """
+ A string naming this mode (e.g. "ECB", "CBC").
+ """
+
+ @abc.abstractmethod
+ def validate_for_algorithm(self, algorithm: CipherAlgorithm) -> None:
+ """
+ Checks that all the necessary invariants of this (mode, algorithm)
+ combination are met.
+ """
+
+
+class ModeWithInitializationVector(Mode, metaclass=abc.ABCMeta):
+ @property
+ @abc.abstractmethod
+ def initialization_vector(self) -> bytes:
+ """
+ The value of the initialization vector for this mode as bytes.
+ """
+
+
+class ModeWithTweak(Mode, metaclass=abc.ABCMeta):
+ @property
+ @abc.abstractmethod
+ def tweak(self) -> bytes:
+ """
+ The value of the tweak for this mode as bytes.
+ """
+
+
+class ModeWithNonce(Mode, metaclass=abc.ABCMeta):
+ @property
+ @abc.abstractmethod
+ def nonce(self) -> bytes:
+ """
+ The value of the nonce for this mode as bytes.
+ """
+
+
+class ModeWithAuthenticationTag(Mode, metaclass=abc.ABCMeta):
+ @property
+ @abc.abstractmethod
+ def tag(self) -> bytes | None:
+ """
+ The value of the tag supplied to the constructor of this mode.
+ """
+
+
+def _check_aes_key_length(self: Mode, algorithm: CipherAlgorithm) -> None:
+ if algorithm.key_size > 256 and algorithm.name == "AES":
+ raise ValueError(
+ "Only 128, 192, and 256 bit keys are allowed for this AES mode"
+ )
+
+
+def _check_iv_length(
+ self: ModeWithInitializationVector, algorithm: BlockCipherAlgorithm
+) -> None:
+ iv_len = len(self.initialization_vector)
+ if iv_len * 8 != algorithm.block_size:
+ raise ValueError(f"Invalid IV size ({iv_len}) for {self.name}.")
+
+
+def _check_nonce_length(
+ nonce: bytes, name: str, algorithm: CipherAlgorithm
+) -> None:
+ if not isinstance(algorithm, BlockCipherAlgorithm):
+ raise UnsupportedAlgorithm(
+ f"{name} requires a block cipher algorithm",
+ _Reasons.UNSUPPORTED_CIPHER,
+ )
+ if len(nonce) * 8 != algorithm.block_size:
+ raise ValueError(f"Invalid nonce size ({len(nonce)}) for {name}.")
+
+
+def _check_iv_and_key_length(
+ self: ModeWithInitializationVector, algorithm: CipherAlgorithm
+) -> None:
+ if not isinstance(algorithm, BlockCipherAlgorithm):
+ raise UnsupportedAlgorithm(
+ f"{self} requires a block cipher algorithm",
+ _Reasons.UNSUPPORTED_CIPHER,
+ )
+ _check_aes_key_length(self, algorithm)
+ _check_iv_length(self, algorithm)
+
+
+class CBC(ModeWithInitializationVector):
+ name = "CBC"
+
+ def __init__(self, initialization_vector: bytes):
+ utils._check_byteslike("initialization_vector", initialization_vector)
+ self._initialization_vector = initialization_vector
+
+ @property
+ def initialization_vector(self) -> bytes:
+ return self._initialization_vector
+
+ validate_for_algorithm = _check_iv_and_key_length
+
+
+class XTS(ModeWithTweak):
+ name = "XTS"
+
+ def __init__(self, tweak: bytes):
+ utils._check_byteslike("tweak", tweak)
+
+ if len(tweak) != 16:
+ raise ValueError("tweak must be 128-bits (16 bytes)")
+
+ self._tweak = tweak
+
+ @property
+ def tweak(self) -> bytes:
+ return self._tweak
+
+ def validate_for_algorithm(self, algorithm: CipherAlgorithm) -> None:
+ if isinstance(algorithm, (algorithms.AES128, algorithms.AES256)):
+ raise TypeError(
+ "The AES128 and AES256 classes do not support XTS, please use "
+ "the standard AES class instead."
+ )
+
+ if algorithm.key_size not in (256, 512):
+ raise ValueError(
+ "The XTS specification requires a 256-bit key for AES-128-XTS"
+ " and 512-bit key for AES-256-XTS"
+ )
+
+
+class ECB(Mode):
+ name = "ECB"
+
+ validate_for_algorithm = _check_aes_key_length
+
+
+class OFB(ModeWithInitializationVector):
+ name = "OFB"
+
+ def __init__(self, initialization_vector: bytes):
+ utils._check_byteslike("initialization_vector", initialization_vector)
+ self._initialization_vector = initialization_vector
+
+ @property
+ def initialization_vector(self) -> bytes:
+ return self._initialization_vector
+
+ validate_for_algorithm = _check_iv_and_key_length
+
+
+class CFB(ModeWithInitializationVector):
+ name = "CFB"
+
+ def __init__(self, initialization_vector: bytes):
+ utils._check_byteslike("initialization_vector", initialization_vector)
+ self._initialization_vector = initialization_vector
+
+ @property
+ def initialization_vector(self) -> bytes:
+ return self._initialization_vector
+
+ validate_for_algorithm = _check_iv_and_key_length
+
+
+class CFB8(ModeWithInitializationVector):
+ name = "CFB8"
+
+ def __init__(self, initialization_vector: bytes):
+ utils._check_byteslike("initialization_vector", initialization_vector)
+ self._initialization_vector = initialization_vector
+
+ @property
+ def initialization_vector(self) -> bytes:
+ return self._initialization_vector
+
+ validate_for_algorithm = _check_iv_and_key_length
+
+
+class CTR(ModeWithNonce):
+ name = "CTR"
+
+ def __init__(self, nonce: bytes):
+ utils._check_byteslike("nonce", nonce)
+ self._nonce = nonce
+
+ @property
+ def nonce(self) -> bytes:
+ return self._nonce
+
+ def validate_for_algorithm(self, algorithm: CipherAlgorithm) -> None:
+ _check_aes_key_length(self, algorithm)
+ _check_nonce_length(self.nonce, self.name, algorithm)
+
+
+class GCM(ModeWithInitializationVector, ModeWithAuthenticationTag):
+ name = "GCM"
+ _MAX_ENCRYPTED_BYTES = (2**39 - 256) // 8
+ _MAX_AAD_BYTES = (2**64) // 8
+
+ def __init__(
+ self,
+ initialization_vector: bytes,
+ tag: bytes | None = None,
+ min_tag_length: int = 16,
+ ):
+ # OpenSSL 3.0.0 constrains GCM IVs to [64, 1024] bits inclusive
+ # This is a sane limit anyway so we'll enforce it here.
+ utils._check_byteslike("initialization_vector", initialization_vector)
+ if len(initialization_vector) < 8 or len(initialization_vector) > 128:
+ raise ValueError(
+ "initialization_vector must be between 8 and 128 bytes (64 "
+ "and 1024 bits)."
+ )
+ self._initialization_vector = initialization_vector
+ if tag is not None:
+ utils._check_bytes("tag", tag)
+ if min_tag_length < 4:
+ raise ValueError("min_tag_length must be >= 4")
+ if len(tag) < min_tag_length:
+ raise ValueError(
+ f"Authentication tag must be {min_tag_length} bytes or "
+ "longer."
+ )
+ self._tag = tag
+ self._min_tag_length = min_tag_length
+
+ @property
+ def tag(self) -> bytes | None:
+ return self._tag
+
+ @property
+ def initialization_vector(self) -> bytes:
+ return self._initialization_vector
+
+ def validate_for_algorithm(self, algorithm: CipherAlgorithm) -> None:
+ _check_aes_key_length(self, algorithm)
+ if not isinstance(algorithm, BlockCipherAlgorithm):
+ raise UnsupportedAlgorithm(
+ "GCM requires a block cipher algorithm",
+ _Reasons.UNSUPPORTED_CIPHER,
+ )
+ block_size_bytes = algorithm.block_size // 8
+ if self._tag is not None and len(self._tag) > block_size_bytes:
+ raise ValueError(
+ f"Authentication tag cannot be more than {block_size_bytes} "
+ "bytes."
+ )