I have a desktop program (Windows C# .NET) that has a GUID stored in a Firebird database. PayPal has an optional field that I want to fill when the user clicks a Buy Now button on a webpage on my site. The PayPal page, my webpage that displays the Buy Now button and the C# program all reside on the same machine.
How do I get the GUID into the PayPal webpage once it's displayed on the user's machine (where the Firebird database is located)?
This is to encrypt a registration date that will be sent to me from PayPal so I can send the encrypted date (using the GUID) back to the user after he pays the registration fee.