C#

Boolean SetComputerName(String name)
{
   String RegLocComputerName = @"SYSTEM\CurrentControlSet\Control\ComputerName\ComputerName";
   try
   {
       string compPath= "Win32_ComputerSystem.Name='" + System.Environment.MachineName + "'";
       //using (ManagementObject mo = new ManagementObject(new ManagementPath(compPath)))
           //using (ManagementObject mo = new ManagementObject("root\\cimv2",compPath,null))
           //ManagementClass mo = new ManagementClass("Win32_ComputerSystem");
           ManagementObject mo = new ManagementObject(compPath);
           {
           ManagementBaseObject inputArgs = mo.GetMethodParameters("Rename");
           inputArgs["Name"] = name;
           //inputArgs["Password"]=null;
           //inputArgs["UserName"]=null;  // use the current user
           ManagementBaseObject output = mo.InvokeMethod("Rename", inputArgs, null);
           uint retValue = (uint)Convert.ChangeType(output.Properties["ReturnValue"].Value, typeof(uint));
           if (retValue != 0)
           {
               MessageBox.Show(String.Format("Computer could not be changed due to unknown reason. return = {0}",retValue));
               throw new Exception("Computer could not be changed due to unknown reason.");
           }
       }

       RegistryKey ComputerName = Registry.LocalMachine.OpenSubKey(RegLocComputerName);
       if (ComputerName == null)
       {
           throw new Exception("Registry location '" + RegLocComputerName + "' is not readable.");
       }
       if (((String)ComputerName.GetValue("ComputerName")) != Name)
       {
           throw new Exception("The computer name was set by WMI but was not updated in the registry location: '" + RegLocComputerName + "'");
       }
       ComputerName.Close();
       ComputerName.Dispose();
   }
   catch (Exception ex)
   {
       return false;
   }
   return true;
}

public static void EncryptFile(string inputFile, string outputFile, string skey)
      {
          RijndaelManaged aes = new RijndaelManaged();
          try
          {
              byte[] key = ASCIIEncoding.UTF8.GetBytes(skey);

              using (FileStream fsCrypt = new FileStream(outputFile, FileMode.Create))
              {
                  using (CryptoStream cs = new CryptoStream(fsCrypt, aes.CreateEncryptor(key, key), CryptoStreamMode.Write))
                  {
                      using (FileStream fsIn = new FileStream(inputFile, FileMode.Open))
                      {
                          int data;

                          while ((data = fsIn.ReadByte()) != -1)
                          {
                              cs.WriteByte((byte)data);
                          }

                          aes.Clear();
                      }
                  }
              }
          }
          catch (Exception ex)
          {
              Console.WriteLine(ex.Message);
              aes.Clear();
          }
      }

private static void DecryptFile(string inputFile, string outputFile, string skey)
        {
            RijndaelManaged aes = new RijndaelManaged();

            try
            {
                byte[] key = ASCIIEncoding.UTF8.GetBytes(skey);

                using (FileStream fsCrypt = new FileStream(inputFile, FileMode.Open))
                {
                    using (FileStream fsOut = new FileStream(outputFile, FileMode.Create))
                    {
                        using (CryptoStream cs = new CryptoStream(fsCrypt, aes.CreateDecryptor(key, key), CryptoStreamMode.Read))
                        {
                            int data;

                            while ((data = cs.ReadByte()) != -1)
                            {
                                fsOut.WriteByte((byte)data);
                            }

                            aes.Clear();
                        }
                    }
                }

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                aes.Clear();
            }
        }