com.infinities.skyport.util.RSAUtil.java Source code

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Here is the source code for com.infinities.skyport.util.RSAUtil.java

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/*******************************************************************************
 * Copyright 2015 InfinitiesSoft Solutions Inc.
 *
 * 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 com.infinities.skyport.util;

import java.io.File;
import java.io.IOException;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Security;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

import org.bouncycastle.openssl.jcajce.JcaPEMWriter;

import com.google.common.base.Charsets;
import com.google.common.io.BaseEncoding;
import com.google.common.io.Files;

public class RSAUtil {

    private RSAUtil() {

    }

    public static KeyPair generateKeys() throws NoSuchAlgorithmException {
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
        keyGen.initialize(2048);
        return keyGen.genKeyPair();
    }

    public static String extractAndSaveKey(KeyPair keys, File file) throws IOException {
        String privateKeyStr = extractPrivateKey(keys);
        savePem(file, privateKeyStr);
        return privateKeyStr;
    }

    private static String extractPrivateKey(KeyPair keys) throws IOException {
        StringWriter writer = new StringWriter();
        JcaPEMWriter pemWriter = null;
        try {
            pemWriter = new JcaPEMWriter(writer);
            pemWriter.writeObject(keys.getPrivate());
        } finally {
            if (pemWriter != null) {
                pemWriter.close();
            }
        }
        return writer.toString();
    }

    private static void savePem(File file, String privateKeyStr) throws IOException {
        Files.write(privateKeyStr, file, Charsets.UTF_8);
    }

    public static String encrypt(String message, PublicKey key)
            throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException,
            BadPaddingException, UnsupportedEncodingException {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, key);

        byte[] stringBytes = message.getBytes("UTF8");
        byte[] raw = cipher.doFinal(stringBytes);
        String base64 = BaseEncoding.base64().encode(raw);
        return base64;
    }

    public static String decrypt(String encrypted, PrivateKey key)
            throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException,
            BadPaddingException, UnsupportedEncodingException {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, key);

        byte[] raw = BaseEncoding.base64().decode(encrypted);

        byte[] stringBytes = cipher.doFinal(raw);
        String clear = new String(stringBytes, "UTF8");
        return clear;
    }

    public static PrivateKey readPrivateKey(byte[] bytes) throws NoSuchAlgorithmException, InvalidKeySpecException {
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
        PKCS8EncodedKeySpec privspec = new PKCS8EncodedKeySpec(bytes);
        KeyFactory factory = KeyFactory.getInstance("RSA");
        PrivateKey privkey = factory.generatePrivate(privspec);
        return privkey;
    }

}