RSA之JS于JAVA交互,废话不多上代码！

package org.boyz.rsa.rsajs;

/**
 * Created by on 2015/1/6.
 */

import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.Cipher;
import java.io.*;
import java.math.BigInteger;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;

/**
 * RSA 工具类。提供加密，解密，生成密钥对等方法。
 * 需要到http://www.bouncycastle.org下载bcprov-jdk14-123.jar。
 * RSA工具类，主要针对RSA.js使用
 * 用法：
 * 1、使用generateKeyPair()方法生成密钥文件
 * 2、公钥信息给客户端使用
 * 3、私钥信息给服务端使用
 * 4、客户端公钥加密传给服务端，服务端私钥解密。
 * 5、服务端私钥加密传给客户端，客户端公钥解密。
 * 6、私钥在任何情况下不能暴露于客户端。
 */
public class RSAUtil {
    // 生成密钥文件
    private static String RSAKeyStore = "C:/RSAKey.txt";
    /**
     * 生成密钥
     * @return
     * @throws Exception
     */
    public static KeyPair generateKeyPair() throws Exception {
        try {
            KeyPairGenerator keyPairGen =
                    KeyPairGenerator.getInstance("RSA",new BouncyCastleProvider());
            final int KEY_SIZE = 512; // 密钥大小
            keyPairGen.initialize(KEY_SIZE, new SecureRandom());
            KeyPair keyPair = keyPairGen.generateKeyPair();
            System.out.println(keyPair.getPrivate());
            System.out.println(keyPair.getPublic());
            saveKeyPair(keyPair);
            return keyPair;
        } catch (Exception e) {
            throw new Exception(e.getMessage());
        }
    }

    /**
     * 实际使用中不会经常生成密钥，而是获取密钥。密钥可以定期更换。
     * @return
     * @throws Exception
     */
    public static KeyPair getKeyPair() throws Exception {
        FileInputStream fis = new FileInputStream(RSAKeyStore);
        ObjectInputStream oos = new ObjectInputStream(fis);
        KeyPair kp = (KeyPair) oos.readObject();
        oos.close();
        fis.close();
        return kp;
    }

    /**
     *
     * @param kp
     * @throws Exception
     */
    public static void saveKeyPair(KeyPair kp) throws Exception {
        FileOutputStream fos = new FileOutputStream(RSAKeyStore);
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(kp);
        oos.close();
        fos.close();
    }

    /**
     * 生成公钥
     * @param modulus
     * @param publicExponent
     * @return
     * @throws Exception
     */
    public static RSAPublicKey generateRSAPublicKey(byte[] modulus,
                                                    byte[] publicExponent) throws Exception {
        KeyFactory keyFac = null;
        try {
            keyFac = KeyFactory.getInstance("RSA",new BouncyCastleProvider());
        } catch (NoSuchAlgorithmException ex) {
            throw new Exception(ex.getMessage());
        }
        RSAPublicKeySpec pubKeySpec =
                new RSAPublicKeySpec(new BigInteger(modulus), new BigInteger(publicExponent));
        try {
            return (RSAPublicKey) keyFac.generatePublic(pubKeySpec);
        } catch (InvalidKeySpecException ex) {
            throw new Exception(ex.getMessage());
        }
    }

    /**
     * 生成私钥
     * @param modulus
     * @param privateExponent
     * @return
     * @throws Exception
     */
    public static RSAPrivateKey generateRSAPrivateKey(byte[] modulus,
                                                      byte[] privateExponent) throws Exception {
        KeyFactory keyFac = null;
        try {
            keyFac = KeyFactory.getInstance("RSA",
                    new BouncyCastleProvider());
        } catch (NoSuchAlgorithmException ex) {
            throw new Exception(ex.getMessage());
        }
        RSAPrivateKeySpec priKeySpec =
                new RSAPrivateKeySpec(new BigInteger(modulus), new BigInteger(privateExponent));
        try {
            return (RSAPrivateKey) keyFac.generatePrivate(priKeySpec);
        } catch (InvalidKeySpecException ex) {
            throw new Exception(ex.getMessage());
        }
    }

    /**
     * 公钥加密
     * @param pk
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encrypt(PublicKey pk, byte[] data) throws Exception {
        try {
            Cipher cipher = Cipher.getInstance("RSA",
                    new Bo