RsaUtils.java

package com.xiongyingqi.util;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.crypto.Cipher;
import java.io.*;
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;

public class RsaUtils {
    /**
     * 指定加密算法为RSA
     */
    public static final String ALGORITHM = "RSA";
    /**
     * 密钥长度，用来初始化
     */
    private static final int KEYSIZE = 1024;
    /**
     * 指定公钥存放文件
     */
    private static String PUBLIC_KEY_FILE = "PublicKey";
    /**
     * 指定私钥存放文件
     */
    private static String PRIVATE_KEY_FILE = "PrivateKey";

    /**
     * 生成密钥对
     *
     * @throws Exception
     */
    private static void generateKeyPair() throws Exception {

//        /** RSA算法要求有一个可信任的随机数源 */
//        SecureRandom secureRandom = new SecureRandom();

        /** 为RSA算法创建一个KeyPairGenerator对象 */
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(ALGORITHM);

        /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */
//        keyPairGenerator.initialize(KEYSIZE, secureRandom);
        keyPairGenerator.initialize(KEYSIZE);

        /** 生成密匙对 */
        KeyPair keyPair = keyPairGenerator.generateKeyPair();

        /** 得到公钥 */
        Key publicKey = keyPair.getPublic();

        /** 得到私钥 */
        Key privateKey = keyPair.getPrivate();

        ObjectOutputStream oos1 = null;
        ObjectOutputStream oos2 = null;
        try {
            /** 用对象流将生成的密钥写入文件 */
            oos1 = new ObjectOutputStream(new FileOutputStream(PUBLIC_KEY_FILE));
            oos2 = new ObjectOutputStream(new FileOutputStream(PRIVATE_KEY_FILE));
            oos1.writeObject(publicKey);
            oos2.writeObject(privateKey);
        } catch (Exception e) {
            throw e;
        } finally {
            /** 清空缓存，关闭文件输出流 */
            oos1.close();
            oos2.close();
        }
    }

    /**
     * 加密方法
     *
     * @param source 源数据
     * @return
     * @throws Exception
     * @deprecated
     */
    private static String encrypt(String source) throws Exception {
        generateKeyPair();
        Key publicKey;
        ObjectInputStream ois = null;
        try {
            /** 将文件中的公钥对象读出 */
            ois = new ObjectInputStream(new FileInputStream(
                    PUBLIC_KEY_FILE));
            publicKey = (Key) ois.readObject();
        } catch (Exception e) {
            throw e;
        } finally {
            ois.close();
        }

        /** 得到Cipher对象来实现对源数据的RSA加密 */
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] b = source.getBytes();
        /** 执行加密操作 */
        byte[] b1 = cipher.doFinal(b);
        BASE64Encoder encoder = new BASE64Encoder();
        return encoder.encode(b1);
    }

    /**
     * 解密算法
     *
     * @param cryptograph 密文
     * @return
     * @throws Exception
     */
    private static String decrypt(String cryptograph) throws Exception {
        Key privateKey;
        ObjectInputStream ois = null;
        try {
            /** 将文件中的私钥对象读出 */
            ois = new ObjectInputStream(new FileInputStream(
                    PRIVATE_KEY_FILE));
            privateKey = (Key) ois.readObject();
        } catch (Exception e) {
            throw e;
        } finally {
            ois.close();
        }

        /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        BASE64Decoder decoder = new BASE64Decoder();
        byte[] b1 = decoder.decodeBuffer(cryptograph);

        /** 执行解密操作 */
        byte[] b = cipher.doFinal(b1);
        return new String(b);
    }

    /**
     * 生成密钥对
     *
     */
    public KeyPair generatorKeyPair() throws NoSuchAlgorithmException {
        return generatorKeyPair(ALGORITHM, KEYSIZE);
    }

    /**
     * 生成密钥对
     *
     * @param algorithm
     * @param keySize
     * @return
     * @throws java.security.NoSuchAlgorithmException
     */
    public KeyPair generatorKeyPair(String algorithm, int keySize) throws NoSuchAlgorithmException {
        /** 为RSA算法创建一个KeyPairGenerator对象 */
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(algorithm);

        /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */
//        keyPairGenerator.initialize(KEYSIZE, secureRandom);
        keyPairGenerator.initialize(keySize);

        /** 生成密匙对 */
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        return keyPair;
    }

    public String encrypt(String source, Key publicKey) throws Exception {
        return encrypt(source, publicKey, ALGORITHM);
    }

    public String encrypt(String source, Key publicKey, String algorithm) throws Exception {
        /** 得到Cipher对象来实现对源数据的RSA加密 */
        Cipher cipher = Cipher.getInstance(algorithm);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] b = source.getBytes();
        /** 执行加密操作 */
        byte[] b1 = cipher.doFinal(b);
        BASE64Encoder encoder = new BASE64Encoder();
        return encoder.encode(b1);
    }

    public String encrypt(String source, KeyPair keyPair) throws Exception {
        return encrypt(source, keyPair.getPublic());
    }

    public String decrypt(String cryptograph, Key privateKey) throws Exception {
        return decrypt(cryptograph, privateKey, ALGORITHM);
    }

    public String decrypt(String cryptograph, Key privateKey, String algorithm) throws Exception {
        /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */
        Cipher cipher = Cipher.getInstance(algorithm);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        BASE64Decoder decoder = new BASE64Decoder();
        byte[] b1 = decoder.decodeBuffer(cryptograph);

        /** 执行解密操作 */
        byte[] b = cipher.doFinal(b1);
        return new String(b);
    }

    /**
     * 解密算法
     *
     * @param cryptograph 密文
     * @return
     * @throws Exception
     */
    public String decrypt(String cryptograph, KeyPair keyPair) throws Exception {
        return decrypt(cryptograph, keyPair.getPrivate());
    }

    public static void main(String[] args) throws Exception {
//        String source = "恭喜发财!";// 要加密的字符串
//        System.out.println("准备用公钥加密的字符串为：" + source);
//
//        String cryptograph = encrypt(source);// 生成的密文
//        System.out.print("用公钥加密后的结果为:" + cryptograph);
//        System.out.println();
//
//        String target = decrypt(cryptograph);// 解密密文
//        System.out.println("用私钥解密后的字符串为：" + target);
//        System.out.println();

        RsaUtils rsaUtils = new RsaUtils();
        KeyPair keyPair = rsaUtils.generatorKeyPair();
        String secret = rsaUtils.encrypt(StringUtil.randomString(117), keyPair);
        String message = rsaUtils.decrypt(secret, keyPair);

        ByteArrayOutputStream arrayOutputStream = new ByteArrayOutputStream();
        ObjectOutputStream outputStream = new ObjectOutputStream(arrayOutputStream);
        outputStream.writeObject(keyPair.getPrivate());
        outputStream.flush();
        outputStream.close();
        arrayOutputStream.flush();
        arrayOutputStream.close();
        EntityHelper.print(arrayOutputStream.toString().length());

        System.out.println(message);
        System.out.println(keyPair.getPrivate());
        System.out.println(keyPair.getPublic());
        System.out.println(secret);
    }
}