RSA加密解密

参考：

1，http://blog.csdn.net/MJM_49/article/details/77429883

2，http://blog.csdn.net/defonds/article/details/42775183

3，http://blog.csdn.net/centralperk/article/details/8538697

4，http://blog.csdn.net/wang8978/article/details/52279661（涉及加密之后的byte[]转String，String转byte[]不一致的问题）

5，http://blog.csdn.net/qq_27760433/article/details/78327328

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;

public class EncrypRSAUtil {

    /**
     * 加密
     *
     * @param publicKey
     * @param srcBytes
     * @return
     * @throws NoSuchAlgorithmException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     */
    protected byte[] encrypt(RSAPublicKey publicKey, byte[] srcBytes) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        if (publicKey != null) {
            //Cipher负责完成加密或解密工作，基于RSA
            Cipher cipher = Cipher.getInstance("RSA");
            //根据公钥，对Cipher对象进行初始化
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            return cipher.doFinal(srcBytes);
        }
        return null;
    }

    /**
     * 解密
     *
     * @param privateKey
     * @param srcBytes
     * @return
     * @throws NoSuchAlgorithmException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     */
    protected byte[] decrypt(RSAPrivateKey privateKey, byte[] srcBytes) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        if (privateKey != null) {
            //Cipher负责完成加密或解密工作，基于RSA
            Cipher cipher = Cipher.getInstance("RSA");
            //根据公钥，对Cipher对象进行初始化
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            return cipher.doFinal(srcBytes);
        }
        return null;
    }

    /**
     * The method checks if the pair of public and private key has been
     * generated.
     *
     * @return flag indicating if the pair of keys were generated.
     */
    public static boolean areKeysPresent() {

        File privateKey = new File(PRIVATE_KEY_FILE);
        File publicKey = new File(PUBLIC_KEY_FILE);

        if (privateKey.exists() && publicKey.exists()) {
            return true;
        }
        return false;
    }

    /**
     * String to hold the name of the private key file.
     */
    public static final String PRIVATE_KEY_FILE = "/tmp/rsatest/private.key";

    /**
     * String to hold name of the public key file.
     */
    public static final String PUBLIC_KEY_FILE = "/tmp/rsatest/public.key";

    /**
     * @param args
     * @throws NoSuchAlgorithmException
     * @throws BadPaddingException
     * @throws IllegalBlockSizeException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     */
    public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeyException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException, IOException, ClassNotFoundException {
        EncrypRSAUtil rsa = new EncrypRSAUtil();
        //KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        //初始化密钥对生成器，密钥大小为1024位
        keyPairGen.initialize(1024);
        //生成一个密钥对，保存在keyPair中
        KeyPair keyPair = keyPairGen.generateKeyPair();

        if (!areKeysPresent()) {

            File privateKeyFile = new File(PRIVATE_KEY_FILE);
            File publicKeyFile = new File(PUBLIC_KEY_FILE);

            // Create files to store public and private key
            if (privateKeyFile.getParentFile() != null) {
                privateKeyFile.getParentFile().mkdirs();
            }
            privateKeyFile.createNewFile();

            if (publicKeyFile.getParentFile() != null) {
                publicKeyFile.getParentFile().mkdirs();
            }
            publicKeyFile.createNewFile();

            // Saving the Public key in a file
            ObjectOutputStream publicKeyOS = new ObjectOutputStream(
                    new FileOutputStream(publicKeyFile));
            publicKeyOS.writeObject(keyPair.getPublic());
            publicKeyOS.close();

            // Saving the Private key in a file
            ObjectOutputStream privateKeyOS = new ObjectOutputStream(
                    new FileOutputStream(privateKeyFile));
            privateKeyOS.writeObject(keyPair.getPrivate());
            privateKeyOS.close();
        }

        ObjectInputStream inputStream = null;

        // Decrypt the cipher text using the private key.
        inputStream = new ObjectInputStream(new FileInputStream(PRIVATE_KEY_FILE));

        //得到私钥
        RSAPrivateKey privateKey = (RSAPrivateKey) inputStream.readObject();

        // Encrypt the string using the public key
        inputStream = new ObjectInputStream(new FileInputStream(PUBLIC_KEY_FILE));
        //得到公钥
        RSAPublicKey publicKey = (RSAPublicKey) inputStream.readObject();

        String msg = "郭XX-精品相声";
        byte[] srcBytes = msg.getBytes();

        //用公钥加密
        byte[] resultBytes = rsa.encrypt(publicKey, srcBytes);

        //用私钥解密
        byte[] decBytes = rsa.decrypt(privateKey, resultBytes);

        System.out.println("明文是:" + msg);
        System.out.println("加密后是:" + new String(resultBytes));
        System.out.println("解密后是:" + new String(decBytes));
    }

    /**
     * 公钥
     */
    private static RSAPublicKey publicKey;

    static {
        try (ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream(Resources.getResource("public.key").getFile()))) {
            publicKey = (RSAPublicKey) inputStream.readObject();
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    private static String generateToken() throws IOException, ClassNotFoundException, NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
        String tokenValue = "-TOKEN-" + Calendar.getInstance().getTimeInMillis();
        // Cipher负责完成加密或解密工作，基于RSA
        Cipher cipher = Cipher.getInstance("RSA");
        //根据公钥，对Cipher对象进行初始化
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return new String(cipher.doFinal(tokenValue.getBytes()), "ISO-8859-1");
    }

    public static void main(String[] args) throws NoSuchPaddingException, NoSuchAlgorithmException, IOException, BadPaddingException, IllegalBlockSizeException, InvalidKeyException, ClassNotFoundException {
        String en = HttpRequestUtils.generateToken();
        ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream(Resources.getResource("private.key").getFile()));
        RSAPrivateKey privateKey = (RSAPrivateKey) inputStream.readObject();
        //Cipher负责完成加密或解密工作，基于RSA
        Cipher cipher = Cipher.getInstance("RSA");
        //根据公钥，对Cipher对象进行初始化
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] de = cipher.doFinal(en.getBytes("ISO-8859-1"));
        System.out.println(new String(de));
    }