Here is the situation: I have a website which is not secured (not https) and available on different domains depending on the country (.fr, .ca, .com, .es, etc). All of these domains have one page where a user chooses an option. Then later on, the user has to go on a buy.php page which is located on our secure domain (secured.domain.com). That page must be able to have access to the option that the user has chosen.
Furthermore, if the user goes directly to the buy.php page, it can still choose the option and when the user goes back to its original non-secured domain, the non-secured domain must also be able to read this option.
We have, for the moment, a cookie but of course it cannot be read on both domains.
How can I do this?