java封装AES加密算法

在实际coding中会经常遇到往数据库存入密码时加密,URL传参时的加密,由此简单封装了下java中的AES加密算法。

0、import类

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.apache.axis.encoding.Base64; //非必须

1、加密接口

    /**
     * 加密
     * @param content 待加密内容
     * @param password  加密密钥
     * @return
     */
    public static byte[] encrypt(String content, String password) {
        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(password.getBytes()));
            SecretKey secretKey = kgen.generateKey();
            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            Cipher cipher = Cipher.getInstance("AES");
            byte[] byteContent = content.getBytes("utf-8");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] result = cipher.doFinal(byteContent);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

2、解密接口

    /**解密
     * @param content  待解密内容
     * @param password 解密密钥
     * @return
     */
    public static byte[] decrypt(byte[] content, String password) {
        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(password.getBytes()));
            SecretKey secretKey = kgen.generateKey();
            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.DECRYPT_MODE, key);
            byte[] result = cipher.doFinal(content);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

3、编解码函数(非必须)

    //编码函数
    public static String encode(String content, String key) throws Exception {
        byte[] encrypt = encrypt(content, key);
        return Base64.encode(encrypt);
    }
    //解码函数
    public static String decode(String encode, String key) throws Exception {
        byte[] encrypt = Base64.decode(encode);
        byte[] content = decrypt(encrypt, key);
        return new String(content);
    }

4、测试

    //0-正常使用
    public static void main(String[] args) throws Exception{
        String content = "holybin";
        String password = "12345678";

        System.out.println("加密前1:" + content);
        byte[] encryptResult1 = encrypt(content, password); //普通加密
        byte[] decryptResult1 = decrypt(encryptResult1,password);   //普通解密
        System.out.println("解密后1:" + new String(decryptResult1));

        System.out.println("\n加密前2:" + content);
        String encryptResult2 = encode(content, password);  //先编码再加密
        System.out.println("加密后2:" + encryptResult2);
        String decryptResult2 = decode(encryptResult2, password);   //先解码再解密
        System.out.println("解密后2:" + decryptResult2);
    }

结果如下:
java封装AES加密算法_第1张图片

5、问题与思考

(1)普通加密后将得到的byte数组直接转化为字符串用于输出,或者普通解密时从字符串转换为byte数组用于传参会发生什么?

    //1-先测试加密
    public static void main(String[] args) throws Exception{
        String content = "holybin";
        String password = "12345678";

        System.out.println("加密前1:" + content);
        byte[] encryptResult1 = encrypt(content, password); //普通加密
        System.out.println("加密后1:" + encryptResult1);
        System.out.println("加密后1:" + new String(encryptResult1));
        byte[] decryptResult1 = decrypt(encryptResult1,password);   //普通解密
        System.out.println("解密后1:" + new String(decryptResult1));
    }

结果1:
这里写图片描述
这里将加密后的byte数组直接转化成String输出,出现乱码。

    //2-再测试解密
    public static void main(String[] args) throws Exception{
        String content = "holybin";
        String password = "12345678";

        System.out.println("加密前1:" + content);
        byte[] encryptResult1 = encrypt(content, password); //普通加密
        String strEncryptResult1 = new String(encryptResult1,"UTF-8");
        //System.out.println("加密后1:" + strEncryptResult1);
        byte[] decryptResult1 = decrypt(strEncryptResult1.getBytes("UTF-8"),password);  //普通解密
        System.out.println("解密后1:" + new String(decryptResult1));
    }

结果2:
这里从加密后的String提取bytes数组用于解密,出现报错
java封装AES加密算法_第2张图片

原因:主要是因为加密后的byte数组是不能强制转换成字符串的,加密过的字符串也不能直接提取bytes数组用于解密,解决方法有两个:一是像上面测试的例子一样先加密再编码,或先解码再解密(参考:4、测试);二是采用十六进制和二进制的相互转化函数(参考:下面的第(2)点)。

(2)十六进制和二进制相互转化函数

    // 二进制转十六进制
    public static String parseByte2HexStr(byte buf[]) {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < buf.length; i++) {
            String hex = Integer.toHexString(buf[i] & 0xFF);
            if (hex.length() == 1) {
                hex = '0' + hex;
            }
            sb.append(hex.toUpperCase());
        }
        return sb.toString();
    }

    // 十六进制转二进制
    public static byte[] parseHexStr2Byte(String hexStr) {
        if (hexStr.length() < 1)
            return null;
        byte[] result = new byte[hexStr.length() / 2];
        for (int i = 0; i < hexStr.length() / 2; i++) {
            int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
            int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2),
                    16);
            result[i] = (byte) (high * 16 + low);
        }
        return result;
    }

使用示例:

    // 3-测试转化函数
    public static void main(String[] args) throws Exception {
        String content = "holybin";
        String password = "12345678";
        //加密
        System.out.println("加密前1:" + content);
        byte[] encryptResult = encrypt(content, password);  // 普通加密
        String strEncryptResult = parseByte2HexStr(encryptResult);
        System.out.println("加密后1:" + strEncryptResult);
        //解密
        byte[] byteDecryptResult = parseHexStr2Byte(strEncryptResult);
        byte[] decryptResult = decrypt(byteDecryptResult, password);    // 普通解密
        System.out.println("解密后1:" + new String(decryptResult));
    }

结果:
这里写图片描述

测试代码:EncrptDecrypt.java

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