Ultra-Low Latency Security Hardening of Modbus/TCP Protocol Based on ZUC Cryptographic Algorithm

Modbus/TCP is a common industrial control protocol, but security was not considered at the beginning of the design. Many researchers have proposed cryptography-based Modbus/TCP security hardening schemes. However, most of the existing solutions rely on public key algorithm and certificate mechanism, which enforce a large performance loss on resource-constrained industrial control equipment. It results in a great impact on the industrial control environments which usually have strict communication delay jitter requirements. This paper proposes a Modbus/TCP security reinforcement mechanism based on cryptographic algorithms including SM3 and ZUC etc., which can provide ultra-low-latency security protection on the resource-constrained industrial control devices, including the device identity authentication, communication data confidentiality and integrity protection, and anti-replay attack, etc. Taking advantage of the features that the devices deployed in the industrial control environment are relatively fixed and the Modbus/TCP protocol is usually used in the scenarios with low-to-medium-throughput data rate, a protection mechanism based on pre-shared keys and key pre-computation is designed, with which the real-time communication could be protected through a small amount of lightweight XOR operations. The prototype system is implemented on the Cortex-M7 industrial control microcontroller. The performance evaluation results show that for a Modbus/TCP communication, the average communication delay introduced by the real-time protection is 31.2.