I am working on a website that has a store running under osCommerce 2.2 with PayPal as its payment gateway. It appears to be properly configured, but there is a hiccup when users try to apply a coupon toward their purchase. In order to help me isolate the problem, I thought I would set up a PayPal sandbox to see what it is receiving from osc.
I created the API accounts needed to set up the sandbox, and PayPal generated the usernames, passwords and signatures. I then went into the osCommerce admin to modify the payment module to run some test transactions. I could not find a place to enter the signature. I went into the database and failed to find a place for a signature there either, but the database does have a path to a certificate file.
I checked the PayPal documentation and PayPal says that transactions can be run with either a signature or certificate. Further searching failed to turn up a way to generate a certificate for my sandbox seller. I do not want to modify osCommerce to use signatures since it is working fine using certificates in live mode.
How do I complete sandbox setup?