一段常用的加解密代码demo

贴一段常用的加解密代码 

用途： 

App和后端通信时，可对参数加密，防止请求伪造或被劫持后拿到一些敏感数据。 

App提交加密后的参数值，同时带上kid；服务端通过kid，拿到对应的秘钥，通过AES算法解密参数值。 

当然了，不同的kid可以对应不同的秘钥和加密算法。 

 package xx.demo.decrypt;

 import org.apache.commons.codec.binary.Base64;

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

 public class Main {

     //这里测试发现,加密时必须使用PKCS5Padding填充模式, 解密时,则PKCS5Padding和NoPadding 都可以
     //至于原理,待研究
     static String[] conf = new String[] {"1.0.0", "ab3d2e93fc3ff8bd2d48e3fa39750be7", "AES", "AES/ECB/PKCS5Padding", "AES/ECB/PKCS5Padding"};
     static String _source ="{this is json}";
     static String _kid = "1.0.0";

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

         //加密过程: 与解密过程相反
         String encrypt = encrypt(_source, _kid);
         System.out.println(encrypt);

         //解密过程: 加密字符串->Base64解码字节数组->Crypt解密取得字节数组->utf8编码取得字符串
         String src = decrypt(encrypt, _kid);
         System.out.println(src);
     }

     /**
      * 加密
      * @param source 原文
      * @param kid 秘钥对应的key
      * @return
      * @throws Exception
      */
     public static String encrypt(String source,String kid) throws Exception {

         byte[] bytes = source.getBytes("UTF-8");

         SecretKey keytmp = new SecretKeySpec(hexString2Byte(conf[1]), conf[2]);
         Cipher cp_en = Cipher.getInstance(conf[3]);  //加密
         cp_en.init(Cipher.ENCRYPT_MODE, keytmp);

         byte[] encrypt = cp_en.doFinal(bytes);

         byte[] base64Encrypt = Base64.encodeBase64(encrypt);
         String edata = new String(base64Encrypt, "UTF-8");

         return edata;
     }

     /**
      * 解密
      * @param data 密文
      * @param kid 秘钥对应的key
      * @return
      * @throws Exception
      */
     public static String decrypt(String data, String kid) throws Exception {

         byte[] original_bytes = Base64.decodeBase64(data);

         SecretKey keytmp = new SecretKeySpec(hexString2Byte(conf[1]), conf[2]);
         Cipher cp_de = Cipher.getInstance(conf[4]);  //解密
         cp_de.init(Cipher.DECRYPT_MODE, keytmp);

         byte[] zipped = cp_de.doFinal(original_bytes);

         String content =  new String(zipped, "UTF-8");
         return content;
     }

     /**
      * 16进制字符串转为byte[]
      * @param str (字符范围:0-9 A-F)
      * @return
      */
     public static byte[] hexString2Byte(String str) {
         byte[] result = new byte[str.length() / 2];
         for (int i = 0; i < result.length; i++) {
             byte b = (byte) ((((getStrIndex(str.charAt(2 * i))) & 0x0f) << 4) | ((getStrIndex(str.charAt(2 * i + 1))) & 0x0f));
             result[i] = b;
         }
         return result;
     }

     public static int getStrIndex(char c) {
         if (c > '9') {
             return 10 + (c - 'a');
         } else {
             return c - '0';
         }
     }
 }