In recent years, financial science and technology has been integrated into a part of life, ApplePay, AliPay, WeChatPay, PayMe and other electronic digital wallets, I believe you have heard of or used the services, in fact, we are not difficult to find: we are slowly reducing the carrying of physical cash, and enjoy the speed and convenience brought by the electronic digital exchange. I believe that in the near future, we will enter a society free of physical cash. While we have experience in using these Internet financial services, how much do we know about the operations behind this service, the connection between systems and related security? Therefore, I hope to increase this knowledge through the lecture.