Use this block of code.
<asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl=’<%#"/aspnetqueryurl/Details.aspx?query="+RandomString(15)+ GetMd5Hash(eval("aircraftid"))+ RandomString(7) %>’ Text="Read Details"></asp:HyperLink>
Here the function
is used to generate some random numbers which are added before and after your desired value. So when you will need to decode the query string to original value then simply just delete them from head and tail.