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.venv2/Lib/site-packages/cryptography/hazmat/primitives/ciphers/base.py

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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
+import typing
+
+from cryptography.hazmat.bindings._rust import openssl as rust_openssl
+from cryptography.hazmat.primitives._cipheralgorithm import CipherAlgorithm
+from cryptography.hazmat.primitives.ciphers import modes
+
+
+class CipherContext(metaclass=abc.ABCMeta):
+    @abc.abstractmethod
+    def update(self, data: bytes) -> bytes:
+        """
+        Processes the provided bytes through the cipher and returns the results
+        as bytes.
+        """
+
+    @abc.abstractmethod
+    def update_into(self, data: bytes, buf: bytes) -> int:
+        """
+        Processes the provided bytes and writes the resulting data into the
+        provided buffer. Returns the number of bytes written.
+        """
+
+    @abc.abstractmethod
+    def finalize(self) -> bytes:
+        """
+        Returns the results of processing the final block as bytes.
+        """
+
+    @abc.abstractmethod
+    def reset_nonce(self, nonce: bytes) -> None:
+        """
+        Resets the nonce for the cipher context to the provided value.
+        Raises an exception if it does not support reset or if the
+        provided nonce does not have a valid length.
+        """
+
+
+class AEADCipherContext(CipherContext, metaclass=abc.ABCMeta):
+    @abc.abstractmethod
+    def authenticate_additional_data(self, data: bytes) -> None:
+        """
+        Authenticates the provided bytes.
+        """
+
+
+class AEADDecryptionContext(AEADCipherContext, metaclass=abc.ABCMeta):
+    @abc.abstractmethod
+    def finalize_with_tag(self, tag: bytes) -> bytes:
+        """
+        Returns the results of processing the final block as bytes and allows
+        delayed passing of the authentication tag.
+        """
+
+
+class AEADEncryptionContext(AEADCipherContext, metaclass=abc.ABCMeta):
+    @property
+    @abc.abstractmethod
+    def tag(self) -> bytes:
+        """
+        Returns tag bytes. This is only available after encryption is
+        finalized.
+        """
+
+
+Mode = typing.TypeVar(
+    "Mode", bound=typing.Optional[modes.Mode], covariant=True
+)
+
+
+class Cipher(typing.Generic[Mode]):
+    def __init__(
+        self,
+        algorithm: CipherAlgorithm,
+        mode: Mode,
+        backend: typing.Any = None,
+    ) -> None:
+        if not isinstance(algorithm, CipherAlgorithm):
+            raise TypeError("Expected interface of CipherAlgorithm.")
+
+        if mode is not None:
+            # mypy needs this assert to narrow the type from our generic
+            # type. Maybe it won't some time in the future.
+            assert isinstance(mode, modes.Mode)
+            mode.validate_for_algorithm(algorithm)
+
+        self.algorithm = algorithm
+        self.mode = mode
+
+    @typing.overload
+    def encryptor(
+        self: Cipher[modes.ModeWithAuthenticationTag],
+    ) -> AEADEncryptionContext: ...
+
+    @typing.overload
+    def encryptor(
+        self: _CIPHER_TYPE,
+    ) -> CipherContext: ...
+
+    def encryptor(self):
+        if isinstance(self.mode, modes.ModeWithAuthenticationTag):
+            if self.mode.tag is not None:
+                raise ValueError(
+                    "Authentication tag must be None when encrypting."
+                )
+
+        return rust_openssl.ciphers.create_encryption_ctx(
+            self.algorithm, self.mode
+        )
+
+    @typing.overload
+    def decryptor(
+        self: Cipher[modes.ModeWithAuthenticationTag],
+    ) -> AEADDecryptionContext: ...
+
+    @typing.overload
+    def decryptor(
+        self: _CIPHER_TYPE,
+    ) -> CipherContext: ...
+
+    def decryptor(self):
+        return rust_openssl.ciphers.create_decryption_ctx(
+            self.algorithm, self.mode
+        )
+
+
+_CIPHER_TYPE = Cipher[
+    typing.Union[
+        modes.ModeWithNonce,
+        modes.ModeWithTweak,
+        None,
+        modes.ECB,
+        modes.ModeWithInitializationVector,
+    ]
+]
+
+CipherContext.register(rust_openssl.ciphers.CipherContext)
+AEADEncryptionContext.register(rust_openssl.ciphers.AEADEncryptionContext)
+AEADDecryptionContext.register(rust_openssl.ciphers.AEADDecryptionContext)