非对称加密——RSA算法工具类

关于RSA算法的介绍网上一大堆，一句话就是牛B。

package com.demo;

import org.springframework.util.StringUtils;

import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

public class RSAUtils {

    /**
     * 加密（对外暴露）
     * 如果使用 公钥 对数据 进行加密，只有用对应的 私钥 才能 进行解密。
     * 如果使用 私钥 对数据 进行加密，只有用对应的 公钥 才能 进行解密。
     * @param keyStr
     * @param data
     * @return
     * @throws Exception
     */
    public static String encryptData(String keyStr, String data, Boolean isPublicKey) throws Exception {
        if (StringUtils.isEmpty(keyStr)) {
            return "";
        }
        return encryptBASE64(encrypt(getKey(keyStr, isPublicKey), data.getBytes()));
    }

    /**
     * 解密（对外暴露）
     * 如果使用 公钥 对数据 进行加密，只有用对应的 私钥 才能 进行解密。
     * 如果使用 私钥 对数据 进行加密，只有用对应的 公钥 才能 进行解密。
     * @param keyStr
     * @param data
     * @return
     * @throws Exception
     */
    public static String decryptData(String keyStr, String data, Boolean isPublicKey) throws Exception {
        if (StringUtils.isEmpty(keyStr)) {
            return "";
        }
        return new String(decrypt(getKey(keyStr, isPublicKey), decryptBASE64(data)), "UTF-8");
    }

    /**
     * 加密
     * @param key
     * @param srcBytes
     * @return
     */
    private static byte[] encrypt(Key key, byte[] srcBytes) {
        if (key != null) {
            try {
                //Cipher负责完成加密或解密工作，基于RSA
                Cipher cipher = Cipher.getInstance("RSA");
                //对Cipher对象进行初始化
                cipher.init(Cipher.ENCRYPT_MODE, key);
                //加密，结果保存进resultBytes，并返回
                return cipher.doFinal(srcBytes);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    /**
     * 解密
     *
     * @param key
     * @param encBytes
     * @return
     */
    private static byte[] decrypt(Key key, byte[] encBytes) {
        if (key != null) {
            try {
                Cipher cipher = Cipher.getInstance("RSA");
                //对Cipher对象进行初始化
                cipher.init(Cipher.DECRYPT_MODE, key);
                //解密并将结果保存进resultBytes
                return cipher.doFinal(encBytes);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    /**
     * 根据key获取公有或者私有key对象
     * @param keyStr
     * @param isPublicKey
     * @return
     * @throws Exception
     */
    private static Key getKey(String keyStr, Boolean isPublicKey) throws Exception {
        if(isPublicKey){
            return getPublicKey(keyStr);
        }else{
            return getPrivateKey(keyStr);
        }
    }

    /**
     * 根据公有key获取公有key对象
     * @param key
     * @return
     * @throws Exception
     */
    private static RSAPublicKey getPublicKey(String key) throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(key);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return (RSAPublicKey) keyFactory.generatePublic(keySpec);
    }

    /**
     * 根据私有key获取私有对象
     * @param key
     * @return
     * @throws Exception
     */
    private static RSAPrivateKey getPrivateKey(String key) throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(key);
         PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
    }

    /**
     * 获取公有/私有Key
     * @return
     */
    private static KeyPair getRSAKey() {
        KeyPair keyPair = null;
        try {
            //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512位
            keyPairGen.initialize(1024);
            //生成一个密钥对，保存在keyPair中
            keyPair = keyPairGen.generateKeyPair();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return keyPair;
    }

    /**
     * 对字符串进行BASE64Decoder
     * @param key
     * @return
     * @throws Exception
     */
    private static byte[] decryptBASE64(String key) throws Exception {
        return Base64.getDecoder().decode(key);
    }

    /**
     * 对字节数组进行BASE64Encoder
     * @param key
     * @return
     * @throws Exception
     */
    private static String encryptBASE64(byte[] key) throws Exception {
        return  Base64.getEncoder().encodeToString(key);
    }

    public static void main(String[] args) throws Exception {
        // 生成的一对key保存好
        try {
            //得到私钥和公钥
            KeyPair keyPair = getRSAKey();
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

            String pubKey = encryptBASE64(publicKey.getEncoded());
            String priKey = encryptBASE64(privateKey.getEncoded());
            System.out.println("公钥：" + pubKey);
            System.out.println("私钥：" + priKey);

            // 测试
            String message = "QWERDF";

            System.out.println("明文：" + message);
            String jiami = encryptData(pubKey, message, true);
            System.out.println("公钥加密后：" + jiami);
            String jiemi = decryptData(priKey, jiami, false);
            System.out.println("用私钥解密后的结果是:" + jiemi);

            jiami = encryptData(priKey, message, false);
            System.out.println("私钥加密后：" + jiami);
            jiemi = decryptData(pubKey, jiami, true);
            System.out.println("用公钥解密后的结果是:" + jiemi);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

输出：

公钥：MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCw2WgOrzQSnDnVNSFKPyI0FgC+urKg6cSFaAB3KuHo5dM5KQJyjLWas9OSSfGvkfbn9i7APscViTShbu0HbbTVNAIMr29EoReAM1zz4bXMnSmD1Unmks1e05mjXa19BitZnXNyJj6Az9mbkkcdf+u/pH8GQbx0Dp9FLGMP4JjMoQIDAQAB
私钥：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
明文：QWERDF
公钥加密后：QLmRoHyM7bepkqhXj/64QEFTMs5eq1L6XeUi0PQorpb4rsWsGV+PW9x/6xbLXeKfXLI6mrS08d6T37wXX9Ww8TWO9ikJuJQdnFnh6M6x9bvfj7KH01W66NoGNInu0rs3wiZpMolL7rFOp6tGOJ8iBJ+tYZSKb8srOxzwtQgc1Zg=
用私钥解密后的结果是:QWERDF
私钥加密后：LnS182WnGZ8StGvldATzLtzDnGh+GB02eVYuQvWPO6HbY0qS+prr4UipEQoaKK6JwuX1+C0sX4VxaEYG8UOpIgNKR5LCpHTAOXEaMmrLLO8QZeo9MGBLp3DofAlmWvmqOBzhQVq5DJfp4Oyyt4wVZ5UI8i1HoCc/LplW0NjWLbU=
用公钥解密后的结果是:QWERDF

原文地址：https://www.cnblogs.com/LUA123/p/11287715.html