博客 - 简单的RSA加解密工具

import javax.crypto.Cipher;

import java.math.BigInteger;

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;

import java.util.HashMap;

import java.util.Map;

​

/**

 * RSA

 * @author wst 2021年8月5日 上午11:28:32

 *

 */

public class RSAUtils {

    /**

     * 密钥长度 于原文长度对应 以及越长速度越慢

     */

    private final static int KEY_SIZE = 2048;

    /**

     * 用于封装随机产生的公钥与私钥

     */

    private static Map<Integer, String> keyMap = new HashMap<Integer, String>();

    /**

     * 随机生成密钥对

     */

    public static void genKeyPair() throws NoSuchAlgorithmException {

        // 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

        keyPairGen.initialize(KEY_SIZE, new SecureRandom());

        // 生成一个密钥对，保存在keyPair中

        KeyPair keyPair = keyPairGen.generateKeyPair();

        // 得到私钥

        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

        // 得到公钥

        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

        String publicKeyString = Base64.getEncoder().encodeToString(publicKey.getEncoded());

        // 得到私钥字符串

        String privateKeyString = Base64.getEncoder().encodeToString(privateKey.getEncoded());

        // 将公钥和私钥保存到Map

        //0表示公钥

        keyMap.put(0, publicKeyString);

        //1表示私钥

        keyMap.put(1, privateKeyString);

    }

    /**

     * RSA公钥加密

     *

     * @param str       加密字符串

     * @param publicKey 公钥

     * @return 密文

     * @throws Exception 加密过程中的异常信息

     */

    public static String encrypt(String str, String publicKey) throws Exception {

        //base64编码的公钥

        byte[] decoded = Base64.getDecoder().decode(publicKey);

        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));

        //RSA加密

        Cipher cipher = Cipher.getInstance("RSA");

        cipher.init(Cipher.ENCRYPT_MODE, pubKey);

        String outStr = Base64.getEncoder().encodeToString(cipher.doFinal(str.getBytes("ASCII")));

        return outStr;

    }

    /**

     * RSA私钥解密

     *

     * @param str        加密字符串

     * @param privateKey 私钥

     * @return 明文

     * @throws Exception 解密过程中的异常信息

     */

    public static String decrypt(String str, String privateKey) throws Exception {

        //64位解码加密后的字符串

        byte[] inputByte = Base64.getDecoder().decode(str);

        //base64编码的私钥

        byte[] decoded = Base64.getDecoder().decode(privateKey);

        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));

        //RSA解密

        Cipher cipher = Cipher.getInstance("RSA");

        cipher.init(Cipher.DECRYPT_MODE, priKey);

        String outStr = new String(cipher.doFinal(inputByte));

        return outStr;

    }

    /**

     * RSA私钥解密

     *

     * @param s        加密字符串

     * @return MD5密文

     * @throws Exception 解密过程中的异常信息

     */

    public static String GetMD5tring(String s) {

        byte[] secretBytes = null;

        try {

            secretBytes = MessageDigest.getInstance("md5").digest(s.getBytes());

        } catch (NoSuchAlgorithmException e) {

            throw new RuntimeException("没有这个md5算法！");

        }

        String md5code = new BigInteger(1, secretBytes).toString(16);

        for (int i = 0; i < 32 - md5code.length(); i++) {

            md5code = "0" + md5code;

        }

        return md5code;

    }

​

    public static void main(String[] args) throws Exception {

        long temp = System.currentTimeMillis();

        //生成公钥和私钥

        genKeyPair();

        //加密字符串

        System.out.println("公钥:" + keyMap.get(0));

        System.out.println("私钥:" + keyMap.get(1));

        System.out.println("生成密钥消耗时间:" + (System.currentTimeMillis() - temp) / 1000.0 + "秒");

        String message = "RSA测试ABCD~!@#$";

        System.out.println("原文:" + message);

        temp = System.currentTimeMillis();

        String messageEn = encrypt(message, keyMap.get(0));

        System.out.println("密文:" + messageEn);

        System.out.println("加密消耗时间:" + (System.currentTimeMillis() - temp) / 1000.0 + "秒");

        temp = System.currentTimeMillis();

        String messageDe = decrypt(messageEn, keyMap.get(1));

        System.out.println("解密:" + messageDe);

        System.out.println("解密消耗时间:" + (System.currentTimeMillis() - temp) / 1000.0 + "秒");

    }

}

​