Add des use

Author: myloveCc

README.md

@@ -51,8 +51,29 @@ Install-Package NETCore.Encrypt -Version 2.0.1
     var encryptedStr = "xxxx";
     var decrypted = EncryptProvider.AESDecrypt(encryptedStr, key, iv);
     ```
-    
-  ## RSA
+## DES
+
+#### Create DES Key
+
+  ```csharp
+  //des key length is 24 bit
+  var desKey = EncryptProvider.CreateDesKey();
+  ```
+
+#### DES encrypt
+
+    ```csharp
+    var srcString = "des encrypt";
+    var encrypted = EncryptProvider.DESEncrypt(srcString, key);
+    ```
+#### DES decrypt
+
+    ```csharp
+    var encryptedStr = "xxxx";
+    var decrypted = EncryptProvider.DESDecrypt(encryptedStr, key);
+    ```
+
+## RSA
 
   - #### Enum RsaSize