AES

package my;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class Test2 {
    public static void main(String[] args) {
        Test2 t=new Test2();
        t.test0();
        t.test1();
        t.test2();
    }
    
    public void test0(){
        String content = "test";
        System.out.println("原始数据：" + content);
        String password = "12345678";
        //加密
        byte[] encryptResult = encrypt(content, password);
        System.out.println("加密数据：" + new String(encryptResult));
        //解密
        byte[] decryptResult = decrypt(encryptResult, password);
        System.out.println("解密数据：" + new String(decryptResult));
    }
    
    //会报出如下异常，主要是因为加密后的byte数组是不能强制转换成字符串的，
    //字符串和byte数组在这种情况下不是互逆的
    public void test1(){
        String content = "test";
        String password = "12345678";
        //加密
        System.out.println("加密前：" + content);
        byte[] encryptResult = encrypt(content, password);
        try {
                String encryptResultStr = new String(encryptResult,"utf-8");
                //解密
                byte[] decryptResult = decrypt(encryptResultStr.getBytes("utf-8"),password);
                System.out.println("解密后：" + new String(decryptResult));
        } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
        }
    }
    
    //修正test1
    public void test2(){
        String content = "test";
        String password = "12345678";
        //加密
        System.out.println("加密前：" + content);
        byte[] encryptResult = encrypt(content, password);
        String encryptResultStr = parseByte2HexStr(encryptResult);
        System.out.println("加密后：" + encryptResultStr);
        //解密
        byte[] decryptFrom = parseHexStr2Byte(encryptResultStr);
        byte[] decryptResult = decrypt(decryptFrom,password);
        System.out.println("解密后：" + new String(decryptResult));
    }
    

    /**
     * 加密
     * @param content 需要加密的内容
     * @param password  加密密码
     * @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");// 创建密码器
            byte[] byteContent = content.getBytes("utf-8");
            cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化
            byte[] result = cipher.doFinal(byteContent);
            return result; // 加密
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**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");// 创建密码器
            cipher.init(Cipher.DECRYPT_MODE, key);// 初始化
            byte[] result = cipher.doFinal(content);
            return result; // 加密
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }
        return null;
    }
    
    /**将16进制转换为二进制
     * @param hexStr
     * @return
     */
    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;
    }
    
    /**将二进制转换成16进制
     * @param buf
     * @return
     */
    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();
    }
}