Security certificate is a tool used to uniquely confirm the identity of a secure e-commerce transaction party. The Cardholder Security Certificate is an electronic representation of the payment card. Since it is digitally signed by the Certificate Authority, no third party can modify the contents of the certificate. Any credit card holder can participate in secure e-commerce online transactions only if he applies for the corresponding digital certificate. The merchant digital certificate is used to prove the identity of the merchant and its relationship with the receiving bank, indicating that the merchant can accept payments from payment cards. Since the merchant certificate is digitally signed by the Certificate Management Center, no third party can modify the content of the certificate. Only by applying for a merchant digital certificate can any online store participate in secure e-commerce online transactions, sell its own goods or provide services. According to the SET standard, digital certificates are confirmed step by step through a trust cascade relationship. Each certificate is connected to the upper-level CA that signed the certificate, thus forming a tree-structured trust chain. A cardholder certificate is connected to the card issuing bank certificate (CCA), and the CCA is connected to the root CA through the brand CA. A merchant certificate is connected to the merchant CA (MCA), and the MCA is connected to the root CA through the brand CA.