package jdbc.pro.lin;

 import java.security.InvalidKeyException;

 import java.security.MessageDigest;

 import java.security.NoSuchAlgorithmException;

 import javax.crypto.KeyGenerator;

 import javax.crypto.Mac;

 import javax.crypto.SecretKey;

 import javax.crypto.spec.SecretKeySpec;

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

 public class MyMessageDigest {

     public static final String PLAIN_TEXT = "i m a sample";

     public static final String MD_ALGORITHM = "MD5";

     public static final String SHA_ALGORITHM = "SHA-512";

     public static final String MAC_ALGORITHM = "HmacSHA512";

     public static void main(String[] args) {

         System.out.println("MD5: " + MD5(PLAIN_TEXT.getBytes()));

         System.out.println("SHA-512: " + SHA(PLAIN_TEXT.getBytes()));

         System.out.println("HmacSHA512：" + MAC(PLAIN_TEXT.getBytes()));

     }

     /**

      * 1.消息摘要算法，MD家族，有MD2 MD4 MD5，其中MD4 JDK不支持

      *

      * @param plainText

      * @return

      */

     public static String MD5(byte[] plainText) {

         MessageDigest messageDigest;

         try {

             messageDigest = MessageDigest.getInstance(MD_ALGORITHM);

             return Base64.encodeBase64String(messageDigest.digest(plainText));

         } catch (NoSuchAlgorithmException e) {

             // TODO Auto-generated catch block

             e.printStackTrace();

         }

         return null;

     }

     /**

      * 2.SHA Security Hash Algorithm 安全散列算法，固定长度摘要信息 SHA-1 SHA-2( SHA-224

      * SHA-256 SHA-384 SHA-512) 使用的依然是MessageDigest类，JDK不支持224

      *

      * @param plainText

      * @return

      */

     public static String SHA(byte[] plainText) {

         MessageDigest messageDigest;

         try {

             messageDigest = MessageDigest.getInstance(SHA_ALGORITHM);

             return Base64.encodeBase64String(messageDigest.digest(plainText));

         } catch (Exception e) {

             e.printStackTrace();

         }

         return null;

     }

     /**

      * 3.MAC(Message Authentication Code) 消息认证码算法，是含有密钥散列函数算法。

      * 兼容了MD和SHA的特性。

      * 加密过程三步走，与后面要介绍的对称加密和非对称加密是相似的

      * 1) 传入算法，实例化一个加密器

      * 2) 传入密钥，初始化加密器

      * 3) 调用doFinal方法进行加密

      * @param plainText

      * @return

      */

     public static String MAC(byte[] plainText) {

         try {

             byte[] secretBytes = generatorMACSecretKey();

             SecretKey key = restoreMACSecretKey(secretBytes);

             Mac mac = Mac.getInstance(MAC_ALGORITHM);

             mac.init(key);

             return Base64.encodeBase64String(mac.doFinal(plainText));

         } catch (NoSuchAlgorithmException | InvalidKeyException e) {

             // TODO Auto-generated catch block

             e.printStackTrace();

         }

         return null;

     }

     /**

      * MAC生成随机密钥 两步走 1.创建一个KeyGenerator 2.调用KeyGenerator.generateKey方法

      *

      * @return

      */

     public static byte[] generatorMACSecretKey() {

         KeyGenerator keyGenerator;

         try {

             keyGenerator = KeyGenerator.getInstance(MAC_ALGORITHM);

             SecretKey key = keyGenerator.generateKey();

             return key.getEncoded();

         } catch (NoSuchAlgorithmException e) {

             // TODO Auto-generated catch block

             e.printStackTrace();

         }

         return null;

     }

     /**

      * 还原密钥

      *

      * @param secretBytes

      * @return

      */

     public static SecretKey restoreMACSecretKey(byte[] secretBytes) {

         SecretKey key = new SecretKeySpec(secretBytes, MAC_ALGORITHM);

         return key;

     }

 }