java消息摘要算法加密

1.几种消息摘要算法简介

• md（Message Digest） (md2,md4,md5) 128位
• sha（Secure Hash Algorithm）(sha1,sha2)
• mac(Message Authentication Code) 融合md,mac,含有秘钥
  验证数据的完整性
  数字签名核心算法

2.应用场景
md可以用于用户登录密码的加密
sha应用

• 加入约定key
• 增加时间戳
• 排序
  http://**?msg=12Hasd74mh&timestamp=1309488734
  对msg,key,timestamp排序拼接，然后sha加密
  例如，微信公众账号开发开始时的验证

3.实现代码
md算法

    public static void jdkmd()    {        try {            MessageDigest md = MessageDigest.getInstance("md2");            byte[] encodeBytes = md.digest(str.getBytes());            System.out.println(Hex.encodeHexString(encodeBytes));        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    public static void ccmd()    {        byte[] encodeBytes = DigestUtils.md5(str.getBytes());        System.out.println(Hex.encodeHexString(encodeBytes));    }    public static void bcmd()    {        Digest dt = new MD5Digest();        dt.update(str.getBytes(), 0, str.getBytes().length);        byte[] md5Bytes = new byte[dt.getDigestSize()];        dt.doFinal(md5Bytes, 0);        System.out.println("bcmd5:"+org.bouncycastle.util.encoders.Hex.toHexString(md5Bytes));//      try {//          MessageDigest md = org.bouncycastle.jcajce.provider.digest.MD5.Digest.getInstance("md5");//          byte[] encodeBytes = md.digest(str.getBytes());//          System.out.println(org.bouncycastle.util.encoders.Hex.toHexString(encodeBytes));//          //      } catch (NoSuchAlgorithmException e) {//          // TODO Auto-generated catch block//          e.printStackTrace();//      }    }    public static void bcmd4()    {        Security.addProvider(new BouncyCastleProvider());        try {            MessageDigest md = MessageDigest.getInstance("MD4");            byte[] encodeByte = md.digest(str.getBytes());            System.out.println("bcmd4:"+org.bouncycastle.util.encoders.Hex.toHexString(encodeByte));        } catch (NoSuchAlgorithmException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }

sha算法代码实现

    public static void jdksha()    {        try {            MessageDigest sha = MessageDigest.getInstance("SHA-1");            byte[] encodeBytes = sha.digest(str.getBytes());            System.out.println("jdksha1:"+Hex.encodeHexString(encodeBytes));        } catch (NoSuchAlgorithmException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    public static void bcsha()    {        Digest dt = new SHA224Digest();        dt.update(str.getBytes(),0,str.getBytes().length);        byte[] sha224Bytes = new byte[dt.getDigestSize()];        dt.doFinal(sha224Bytes, 0);        System.out.println("bcsha224:"+org.bouncycastle.util.encoders.Hex.toHexString(sha224Bytes));        System.out.println();    }

md和sha的代码实现几乎差不多，二者可以互相借鉴。
mac算法代码实现

    public static void jdkHmacMd5()     {        try {            KeyGenerator keyGenerator = KeyGenerator.getInstance("HmacMD5");//初始化KeyGenerator            //随机产生秘钥            SecretKey secertKey = keyGenerator.generateKey(); //产生秘钥            byte[] key = secertKey.getEncoded();            //产生指定秘钥            key = new byte[]{'a','a','a','a','a','a','a','a','a','a'};//Hex.decodeHex(new char[]{'a','a','a','a','a','a','a','a','a','a'});            secertKey = new SecretKeySpec(key,"HmacMD5");            Mac mac = Mac.getInstance(secertKey.getAlgorithm());//实例化Mac            mac.init(secertKey);//初始化Mac            byte[] encodeByte = mac.doFinal(str.getBytes()); //执行摘要            System.out.println("jdkHmacMd5:"+Hex.encodeHexString(encodeByte));        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    public static void bcHmacMd5()    {        HMac hmac = new HMac(new MD5Digest());        hmac.init(new KeyParameter(new byte[]{'a','a','a','a','a','a','a','a','a','a'}));        hmac.update(str.getBytes(), 0, str.getBytes().length);        byte[] hmacMd5Bytes = new byte[hmac.getMacSize()];        hmac.doFinal(hmacMd5Bytes, 0);        System.out.println("bcHmacMd5:"+org.bouncycastle.util.encoders.Hex.toHexString(hmacMd5Bytes));    }