This was probably asked many times here, but I'm not finding any because I'm not sure what to look for.
I'm developing a simple payment gateway, where partners (consumers) can submit requests so their users can pay and return back.
I will give partners a public key (bound to their domain name), they will use this key on their website (through a script src tag on iframe) to acquire an access token. This access token will be then used to submit requests to my payment gateway.
Question is: what is the technical term in security for what I'm trying to do? And what other methods are there?
Extra info: I have checked how Paypal implements their Buy/Subscribe/Donate buttons, they don't seem to put any sensitive info in the iframe (of the button), how can they make sure of the partner?
Additional note: I don't want my partners to do a server to server call, I want the integration to be very simple from their side.