Secure communication system and method

The invention provides a secure communication system and method. The system comprises: an edge gateway is deployed on an Internet of Things device of a bank branch to which the edge gateway belongs; the CA issuing server is used for generating a CA certificate; the enterprise-level Internet of Things platform is deployed in a head office system and is used for managing each edge gateway; when an execution instruction needs to be sent to the Internet of Things equipment of each bank branch, obtaining a target CA certificate from a CA issuing server, and sending the target CA certificate and the execution instruction to each edge gateway; the edge gateway is used for authenticating the target CA certificate when receiving the execution instruction and the target CA certificate issued by the enterprise-level Internet of Things platform; and after the authentication is passed, updating the execution instruction to the Internet of Things equipment of the bank branch to which the edge gateway belongs. By applying t