Question

How to encrypt and decrypt the Query string and sent,receive to another page?

Page 1

LinkButton InvoiceEdit = sender as LinkButton;
string EditId = InvoiceEdit.CommandArgument.ToString();
Response.Redirect("edit invoice.aspx?EditId=" + EditId);

Page 2

String invoiceId = Request.QueryString["InvoiceId"].ToString();

Answer 1

Your question is not clear. what i understand that seems u want to restrict user to modified url. you can user URL Referrer check on page load
if Request.UrlReferrer.AbsoluteUri == null
{
Response.redirect(“home page”)
}

If someone tried to modify url it will alway return null and you can redirect to home page or some other page to restrict the user.