package com.example.utility;

import java.security.MessageDigest;
import java.util.Random;

import org.apache.commons.codec.binary.Hex;

public class SaltMD5Util {
    public static String generateSaltPassword(String password) { // 生成盐和加盐后的MD5码，并将盐混入到MD5码中,对MD5密码进行加强
        Random random = new Random();
        StringBuilder stringBuilder = new StringBuilder(16);
        stringBuilder.append(random.nextInt(99999999)).append(random.nextInt(99999999));
        int len = stringBuilder.length();
        if (len < 16) {
            for (int i = 0; i < 16 - len; i++) {
                stringBuilder.append("0");
            }
        }
        String salt = stringBuilder.toString();
        password = md5Hex(password + salt);
        char[] cs = new char[48];
        for (int i = 0; i < 48; i += 3) {
            cs[i] = password.charAt(i / 3 * 2);
            char c = salt.charAt(i / 3);
            cs[i + 1] = c;
            cs[i + 2] = password.charAt(i / 3 * 2 + 1);
        }
        return new String(cs);
    }

    public static boolean verifySaltPassword(String password, String md5) { // 验证明文和加盐后的MD5码是否匹配
        char[] cs1 = new char[32];
        char[] cs2 = new char[16];
        for (int i = 0; i < 48; i += 3) {
            cs1[i / 3 * 2] = md5.charAt(i);
            cs1[i / 3 * 2 + 1] = md5.charAt(i + 2);
            cs2[i / 3] = md5.charAt(i + 1);
        }
        String salt = new String(cs2);
        return md5Hex(password + salt).equals(new String(cs1));
    }

    private static String md5Hex(String src) {
        try {
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            byte[] bs = md5.digest(src.getBytes());
            return new String(new Hex().encode(bs));
        } catch (Exception e) {
            return null;
        }
    }
}

// 参考文章：https://blog.csdn.net/weixin_46713508/article/details/129152215