Its main contents include: (1) the name of the certificate owner; (2) the public key of the certificate owner; (3) the validity period of the public key; (4) Companies that issue digital certificates; (5) The digital signature of the company that issued the certificate; (6) The number of the digital certificate. Its function: There are three kinds of digital certificates, that is, a general e-commerce transaction subject is: (1) customer. It is the main service object for enterprises to conduct e-commerce. (2) suppliers. Provide customers with corresponding goods or services in e-commerce. (3) banks. Act as an intermediary for the circulation of trading currency. (4) Certification center. Responsible for issuing digital certificates to prove the identity of the parties to the transaction. Certificates are used to identify trading partners, determine the reliability of contracts and documents, and prevent repudiation. (5) electronic supervision department. Responsible for the monitoring of e-commerce transaction process.