You are working as a security expert in an e-commerce enterprise. Your company recently decided on a short-term collaboration with a small business named BuyMe, and the following issue arose. Whenever your customers purchase any product from BuyMe, the e-commerce website redirects them to the BuyMe website, asking for additional authentication. This results in customers abandoning their purchases. To solve this issue, both enterprises agree to use a single authentication process wherein the users, once logged in to your website, can purchase from BuyMe without additional steps Question: How should you implement this without storing the customers' credentials on the BuyMe server?