MD5 hash result's length support 16 and 32.

Author: catcherwong

src/NETCore.Encrypt/EncryptProvider.cs

@@ -423,30 +423,35 @@ public static RSAKey CreateRsaKey(RsaSize rsaSize = RsaSize.R2048)
         #endregion
 
         #region MD5
-
         /// <summary>
         /// MD5 hash
         /// </summary>
-        /// <param name="srcString">The string to be encrypted</param>
+        /// <param name="srcString">The string to be encrypted.</param>
+        /// <param name="length">The length of hash result , default value is <see cref="MD5Length.L32"/>.</param>
         /// <returns></returns>
-        public static string Md5(string srcString)
+        public static string Md5(string srcString, MD5Length length = MD5Length.L32)
         {
             Check.Argument.IsNotEmpty(srcString, nameof(srcString));
 
+            string str_md5_out = string.Empty;
             using (MD5 md5 = MD5.Create())
             {
                 byte[] bytes_md5_in = Encoding.UTF8.GetBytes(srcString);
                 byte[] bytes_md5_out = md5.ComputeHash(bytes_md5_in);
-                string str_md5_out = BitConverter.ToString(bytes_md5_out);
+
+                str_md5_out = length == MD5Length.L32
+                    ? BitConverter.ToString(bytes_md5_out) 
+                    : BitConverter.ToString(bytes_md5_out, 4, 8);
+               
                 str_md5_out = str_md5_out.Replace("-", "");
                 return str_md5_out;
             }
-        }
+        }        
         #endregion
 
         #region HMACMD5
         /// <summary>
-        /// MD5 hash
+        /// HMACMD5 hash
         /// </summary>
         /// <param name="srcString">The string to be encrypted</param>
         /// <param name="key">encrypte key</param>