Class Cipher

src/cryptography/hazmat/primitives/ciphers/base.py:78–131

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[