I have such problem: in my site for clients will be returned (after he will pay) result page in which he should input personal information. It is page my product and the client should not see its URL-address. What functions i can apply and how to do so that the URL-address will be not visible (or will be encrypted).
There is no way to really mask the URL unless you setup Apache to run a proxy, "proxypass". In this way you can somewhat mask the URL, but you would need to contact your host to allow such thing, if they even will. Otherwise, you can encrypt the data that is passed through using SSL, so you would need to buy an SSL certificate for your domain and set it up, however this does not "encrypt" the actual URL or change the URL in any way as this should be publicly visible.
After paying by PayPal? You could use the Unique Transaction ID posted along with Back to merchant button, then check if its valid with IPN and check if the transaction took place in the last 5 minutes and if it hasn't already been used in your system, if everything looks correct, show the page and log the ID (so same ID cannot be used twice during that 5 minutes)
there is a way to code the url. i have seen on a wabsite. it turns the url like: http://xxx.com/search.php?encode=YT...lYXJjaF9lbmNvZGVfdGltZSI7aToxMjYyOTQ5NDk4O30= i will check my files and let u know