A Security-Enhanced Modbus TCP Protocol and Authorized Access Mechanism

Abstract

Because of the communication schemes and communication protocols in the industrial control systems (Industrial Control System, ICS) rarely consider security at the beginning of the design, and with the rapid development of the Industrial Internet and the Internet of Things, the ICS network security threats are becoming more and more serious. In this paper, a reliable security-enhanced Modbus TCP protocol is designed to solve the problem of insufficient security of the Modbus TCP protocol which is widely used in ICSs. Under the premise of ensuring reliability, the HMAC algorithm and the SM4 algorithm are used to provide confidentiality and integrity for the communication data of the industrial control system. It uses a time stamp plus a one-time random number and combined with a random number set table to prevent replay attacks. On this basis, an authorized access mechanism based on IP addresses and function codes is proposed.