Juozas Kaziukenas points out a new class in his latest blog post that can be used to make secure connections over to PayPal (encrypted) using their Encrypted Website Payment method.

In my situation, PayPal is only used to pay for orders - cart and order setup is done in our shop, so I do not want to have additional problems with users changing orders numbers, amount to be paid, etc. [...] Only PayPal knows how to decrypt it, because it uses public key encryption technology (you need to upload your certificate in PayPal account).

Some sample usage code is included as is a link to the class itself. His example takes a payment transaction including the item name, amount and currency type and sends it off to the PayPal servers in a connection protected by certificates.