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/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2023 Apryse Group NV
    Authors: Apryse Software.

    This program is offered under a commercial and under the AGPL license.
    For commercial licensing, contact us at https://itextpdf.com/sales.  For AGPL licensing, see below.

    AGPL licensing:
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see .
 */
package com.itextpdf.kernel.crypto;

import com.itextpdf.bouncycastleconnector.BouncyCastleFactoryCreator;
import com.itextpdf.commons.bouncycastle.IBouncyCastleFactory;
import com.itextpdf.kernel.exceptions.KernelExceptionMessageConstant;
import com.itextpdf.kernel.exceptions.PdfException;
import com.itextpdf.kernel.logs.KernelLogMessageConstant;

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Creates an AES Cipher with CBC and padding PKCS5/7.
 */
public class AESCipher {
    
    private static final Logger LOGGER = LoggerFactory.getLogger(AESCipher.class);

    private static final String CIPHER_WITH_PKCS5_PADDING = "AES/CBC/PKCS5Padding";

    private static final IBouncyCastleFactory BOUNCY_CASTLE_FACTORY = BouncyCastleFactoryCreator.getFactory();

    private static Cipher cipher;
    
    static {
        try {
            if ("BC".equals(BOUNCY_CASTLE_FACTORY.getProviderName())) {
                // Do not pass bc provider and use default one here not to require bc provider for this functionality
                // Do not use bc provider in kernel
                cipher = Cipher.getInstance(CIPHER_WITH_PKCS5_PADDING);
            } else {
                cipher = Cipher.getInstance(CIPHER_WITH_PKCS5_PADDING, BOUNCY_CASTLE_FACTORY.getProvider());
            }
        } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
            throw new PdfException(KernelExceptionMessageConstant.ERROR_WHILE_INITIALIZING_AES_CIPHER, e);
        }
    }

    /**
     * Creates a new instance of AESCipher
     *
     * @param forEncryption if true the cipher is initialised for
     *                      encryption, if false for decryption
     * @param key           the key to be used in the cipher
     * @param iv            initialization vector to be used in cipher
     */
    public AESCipher(boolean forEncryption, byte[] key, byte[] iv) {
        try {
            cipher.init(forEncryption ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE,
                    new SecretKeySpec(key, "AES"),
                    new IvParameterSpec(iv));
        } catch (InvalidKeyException | InvalidAlgorithmParameterException e) {
            throw new PdfException(KernelExceptionMessageConstant.ERROR_WHILE_INITIALIZING_AES_CIPHER, e);
        }
    }

    public byte[] update(byte[] inp, int inpOff, int inpLen) {
        return cipher.update(inp, inpOff, inpLen);
    }

    public byte[] doFinal() {
        try {
            return cipher.doFinal();
        } catch (IllegalBlockSizeException | BadPaddingException e) {
            LOGGER.info(KernelLogMessageConstant.ERROR_WHILE_FINALIZING_AES_CIPHER, e);
            return null;
        }
    }
}