ru.jts.authserver.network.crypt.RSAEngine.java Source code

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Here is the source code for ru.jts.authserver.network.crypt.RSAEngine.java

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/*
 * Copyright 2014 jts
 *
 * Licensed under the Apache License, Version 2.0 (the "License")
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ru.jts.authserver.network.crypt;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import java.nio.ByteOrder;
import java.security.*;

/**
 * @author: Camelion
 * @date: 31.10.13/20:22
 */
public class RSAEngine {
    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    private static RSAEngine ourInstance = new RSAEngine();

    public static RSAEngine getInstance() {
        return ourInstance;
    }

    private RSAEngine() {
    }

    public byte[] decrypt(byte[] data, int from, int length) {
        return decrypt0(data, from, length);
    }

    /**
     * @param data   -  ??  
     * @param from
     * @param length
     * @return - ?? ? 
     */
    private byte[] decrypt0(byte[] data, int from, int length) {
        ByteBuf buf = Unpooled.buffer().order(ByteOrder.LITTLE_ENDIAN);
        PrivateKey privateKey = KeyStore.getInstance().getPrivateKey();
        try {
            Cipher rsa = Cipher.getInstance("RSA/ECB/OAEPWithSHA1AndMGF1Padding",
                    BouncyCastleProvider.PROVIDER_NAME);
            rsa.init(Cipher.DECRYPT_MODE, privateKey);

            final int blockSize = rsa.getBlockSize();
            for (int i = from; i < length; i += blockSize) {
                if (i + blockSize > length) {
                    byte[] tempData = rsa.doFinal(data, i, length - i);
                    buf.writeBytes(tempData);
                } else {
                    byte[] tempData = rsa.doFinal(data, i, blockSize);
                    buf.writeBytes(tempData);
                }
            }
        } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | BadPaddingException
                | IllegalBlockSizeException | NoSuchProviderException e) {
            e.printStackTrace();
        }
        return buf.array();
    }
}