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  "   	ˆl–Ãa¾”ªeJu@·p ¸È”Å£ÄƒxL·¿Â  +    	# 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 absolute_import, division, print_function

from cryptography import utils
from cryptography.exceptions import InvalidTag, UnsupportedAlgorithm, _Reasons
from cryptography.hazmat.primitives import ciphers
from cryptography.hazmat.primitives.ciphers import modes


@utils.register_interface(ciphers.CipherContext)
@utils.register_interface(ciphers.AEADCipherContext)
@utils.register_interface(ciphers.AEADEncryptionContext)
class _CipherContext(object):
    _ENCRYPT = 1
    _DECRYPT = 0

    def __init__(self, backend, cipher, mode, operation):
        self._backend = backend
        self._cipher = cipher
        self._mode = mode
        self._operation = operation
        self._tag = None

        if isinstance(self._cipher, ciphers.BlockCipherAlgorithm):
            self._block_size_bytes = self._cipher.block_size // 8
        else:
            self._block_size_bytes = 1

        ctx = self._backend._lib.EVP_CIPHER_CTX_new()
        ctx = self._backend._ffi.gc(
            ctx, self._backend._lib.EVP_CIPHER_CTX_free
        )

        registry = self._backend._cipher_registry
        try:
            adapter = registry[type(cipher), type(mode)]
        except KeyError:
            raise UnsupportedAlgorithm(
                "cipher {0} in {1} mode is not supported "
                "by this backend.".format(
                    cipher.name, mode.name if mode else mode),
                _Reasons.UNSUPPORTED_CIPHER
            )

        evp_cipher = adapter(self._backend, cipher, mode)
        if evp_cipher == self._backend._ffi.NULL:
            raise UnsupportedAlgorithm(
                "cipher {0} in {1} mode is not supported "
                "by this backend.".format(
                    cipher.name, mode.name if mode else mode),
                _Reasons.UNSUPPORTED_CIPHER
            )

        if isinstance(mode, modes.ModeWithInitializationVector):
            iv_nonce = mode.initialization_vector
        elif isinstance(mode, modes.ModeWithNonce):
            iv_nonce = mode.nonce
        else:
            iv_nonce = self._backend._ffi.NULL
        # begin init with cipher and operation type
        res = self._backend._lib.EVP_CipherInit_ex(ctx, evp_cipher,
                                                   self._backend._ffi.NULL,
                                                   self._backend._ffi.NULL,
                                                   self._backend._ffi.NULL,
                                                   operation)
        self._backend.openssl_assert(res != 0)
        # set the key length to handle variable key ciphers
        res = self._backend._lib.EVP_CIPHER_CTX_set_key_length(
            ctx, len(cipher.key)
        )
        self._backend.openssl_assert(res != 0)
        if isinstance(mode, modes.GCM):
            res = self._backend._lib.EVP_CIPHER_CTX_ctrl(
                ctx, self._backend._lib.EVP_CTRL_GCM_SET_IVLEN,
                len(iv_nonce), self._backend._ffi.NULL
            )
            self._backend.openssl_assert(res != 0)
            if operation == self._DECRYPT:
                res = self._backend._lib.EVP_CIPHER_CTX_ctrl(
                    ctx, self._backend._lib.EVP_CTRL_GCM_SET_TAG,
                    len(mode.tag), mode.tag
                )
                self._backend.openssl_assert(res != 0)

        # pass key/iv
        res = self._backend._lib.EVP_CipherInit_ex(
            ctx,
            self._backend._ffi.NULL,
            self._backend._ffi.NULL,
            cipher.key,
            iv_nonce,
            operation
        )
        self._backend.openssl_assert(res != 0)
        # We purposely disable padding here as it's handled higher up in the
        # API.
        self._backend._lib.EVP_CIPHER_CTX_set_padding(ctx, 0)
        self._ctx = ctx

    def update(self, data):
        b