Secure networked control systems under data integrity attacks

Networked control systems (NCSs) have been gaining popularity with their high potential in widespread applications and becoming realizable with the rapid developments in computer, communication and control technologies. This paper addresses the security issues of NCSs, especially data confidentiality and integrity. The data encryption standard (DES) and message digest 5 (MD5) are integrated with the application to encrypt the data transmitted on the network and detect their integrity. The networked predictive control (NPC) method is used to compensate for the additional time delay caused by discarding external attack signals. Thus, a secure networked control system (SNCS) is designed and implemented over the WLAN to control the speed of a DC motor system. Practical experiments have been carried out to demonstrate the effectiveness of the proposed SNCS.