C# HmacMD5 加密

string HmacMD5(string source, string key) 
       { 
           HMACMD5 hmacmd = new HMACMD5(Encoding.Default.GetBytes(key)); 
           byte[] inArray = hmacmd.ComputeHash(Encoding.Default.GetBytes(source)); 
           StringBuilder sb = new StringBuilder(); 
 
           for (int i = 0; i < inArray.Length; i++) 
           { 
               sb.Append(inArray[i].ToString("X2")); 
           } 
            
           hmacmd.Clear(); 
            
           return sb.ToString(); 
       }