JAVA AES加密 解密 , 动态密钥

package com.jst.mdm.commons.util;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.Arrays;
import java.util.Base64;

/**
 * @Author lll
 * @Date 2025/7/4 9:09 （可以根据需要修改）
 */
public class EncryptionUtils {
    // AES加密密钥（16/24/32字节长度）
    //  code + year + month + day
    private static final String BASE_KEY = "iLsdbi33jkjs";


    /**
     * 不可逆加密 - MD5算法
     */
    public static String irreversibleMd5(String input) throws Exception {
        MessageDigest md = MessageDigest.getInstance("MD5");
        byte[] digest = md.digest(input.getBytes(StandardCharsets.UTF_8));

        // 转换为16进制字符串
        StringBuilder hexString = new StringBuilder();
        for (byte b : digest) {
            String hex = Integer.toHexString(0xff & b);
            if (hex.length() == 1){
                hexString.append('0');
            }
            hexString.append(hex);
        }
        return hexString.toString();
    }

    /**
     * 生成符合AES规范的动态密钥
     * @param employeeId 工号（如"001"或"000001"）
     * @param date 指定日期（null则用当前日期）
     * @return 16字节（128位）AES密钥
     */
    private static byte[] generateKey(String employeeId, LocalDate date) throws Exception {
        // 工号标准化：补前导零至6位
        String normalizedId = String.format("%06d", Integer.parseInt(employeeId));

        // 日期格式化：yyyyMMdd
        String dateStr = (date != null ? date : LocalDate.now())
                .format(DateTimeFormatter.BASIC_ISO_DATE);

        // 组合动态密钥因子
        String rawKey = BASE_KEY + normalizedId + dateStr;

        // 使用SHA-256生成固定长度密钥（取前16字节）
        MessageDigest digest = MessageDigest.getInstance("SHA-256");
        byte[] hash = digest.digest(rawKey.getBytes(StandardCharsets.UTF_8));
        // AES-128
        return Arrays.copyOf(hash, 16);
    }

    /**
     * AES加密
     */
    public static String encrypt(String data, String employeeId) throws Exception {
        // 默认使用当前日期
        byte[] keyBytes = generateKey(employeeId, null);
        SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
        //算法/模式/填充
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] encrypted = cipher.doFinal(data.getBytes(StandardCharsets.UTF_8));
        return Base64.getEncoder().encodeToString(encrypted);
    }

    /**
     * AES解密（需使用加密时的相同工号和日期）
     */
    public static String decrypt(String encryptedData, String employeeId, LocalDate date) throws Exception {
        byte[] keyBytes = generateKey(employeeId, date);
        SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");

        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, key);
        byte[] decrypted = cipher.doFinal(Base64.getDecoder().decode(encryptedData));
        return new String(decrypted, StandardCharsets.UTF_8);
    }
}