RSA加密解密

package com.hzcominfo.application.resourcecenter.core.common.util;

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

import javax.crypto.Cipher;
import java.io.IOException;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class RSAUtil {
    //生成秘钥对
    public static KeyPair getKeyPair() throws Exception {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(2048);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        return keyPair;
    }

    //获取公钥(Base64编码)
    public static String getPublicKey(KeyPair keyPair) {
        PublicKey publicKey = keyPair.getPublic();
        byte[] bytes = publicKey.getEncoded();
        return byte2Base64(bytes);
    }

    //获取私钥(Base64编码)
    public static String getPrivateKey(KeyPair keyPair) {
        PrivateKey privateKey = keyPair.getPrivate();
        byte[] bytes = privateKey.getEncoded();
        return byte2Base64(bytes);
    }

    //将Base64编码后的公钥转换成PublicKey对象
    public static PublicKey string2PublicKey(String pubStr) throws Exception {
        byte[] keyBytes = base642Byte(pubStr);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(keySpec);
        return publicKey;
    }

    //将Base64编码后的私钥转换成PrivateKey对象
    public static PrivateKey string2PrivateKey(String priStr) throws Exception {
        byte[] keyBytes = base642Byte(priStr);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }

    //公钥加密
    public static byte[] publicEncrypt(byte[] content, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] bytes = cipher.doFinal(content);
        return bytes;
    }

    //私钥解密
    public static byte[] privateDecrypt(byte[] content, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] bytes = cipher.doFinal(content);
        return bytes;
    }

    //字节数组转Base64编码
    public static String byte2Base64(byte[] bytes) {
        BASE64Encoder encoder = new BASE64Encoder();
        return encoder.encode(bytes);
    }

    //Base64编码转字节数组
    public static byte[] base642Byte(String base64Key) throws IOException {
        BASE64Decoder decoder = new BASE64Decoder();
        return decoder.decodeBuffer(base64Key);
    }

    //用公钥加密
    public static String getPublicKey(String psd) throws Exception {
        //生成RSA公钥和私钥，并Base64编码
        KeyPair keyPair = RSAUtil.getKeyPair();
        String publicKeyStr = RSAUtil.getPublicKey(keyPair);
        //将Base64编码后的公钥转换成PublicKey对象
        PublicKey publicKey = RSAUtil.string2PublicKey(publicKeyStr);
        //用公钥加密
        byte[] publicEncrypt = RSAUtil.publicEncrypt(psd.getBytes(), publicKey);
        //加密后的内容Base64编码
        String byte2Base64 = RSAUtil.byte2Base64(publicEncrypt);
        return byte2Base64;
    }

    //用私钥解密
    public static String getPrivateKey(String byte2Base64) throws Exception {
        String result = "";
        try {
            //生成RSA公钥和私钥，并Base64编码
            KeyPair keyPair = RSAUtil.getKeyPair();
            String privateKeyStr = RSAUtil.getPrivateKey(keyPair);
            //将Base64编码后的私钥转换成PrivateKey对象
            PrivateKey privateKey = RSAUtil.string2PrivateKey(privateKeyStr);
            //加密后的内容Base64解码
            byte[] base642Byte = RSAUtil.base642Byte(byte2Base64);
            //用私钥解密
            byte[] privateDecrypt = RSAUtil.privateDecrypt(base642Byte, privateKey);
            //解密后的明文
            result = new String(privateDecrypt);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    public static void main(String[] args) {
        try {
            //===============生成公钥和私钥，公钥传给客户端，私钥服务端保留==================
            //生成RSA公钥和私钥，并Base64编码
            KeyPair keyPair = RSAUtil.getKeyPair();
            String publicKeyStr = RSAUtil.getPublicKey(keyPair);
            String privateKeyStr = RSAUtil.getPrivateKey(keyPair);
            System.out.println("RSA公钥Base64编码:" + publicKeyStr);
            System.out.println("RSA私钥Base64编码:" + privateKeyStr);

            //=================客户端=================
            String message = "hello, i am infi, good night!";
            //将Base64编码后的公钥转换成PublicKey对象
            PublicKey publicKey = RSAUtil.string2PublicKey(publicKeyStr);
            //用公钥加密
            byte[] publicEncrypt = RSAUtil.publicEncrypt(message.getBytes(), publicKey);
            //加密后的内容Base64编码
            String byte2Base64 = RSAUtil.byte2Base64(publicEncrypt);
            System.out.println("公钥加密并Base64编码的结果：" + byte2Base64);

            //===================服务端================
            //将Base64编码后的私钥转换成PrivateKey对象
            PrivateKey privateKey = RSAUtil.string2PrivateKey(privateKeyStr);
            //加密后的内容Base64解码
            byte[] base642Byte = RSAUtil.base642Byte(byte2Base64);
            //用私钥解密
            byte[] privateDecrypt = RSAUtil.privateDecrypt(base642Byte, privateKey);
            //解密后的明文
            System.out.println("解密后的明文: " + new String(privateDecrypt));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}