Message security for automation and control applications based on IEC61131-3

Cyber-Physical Systems are integration of computer-based equipment used in industrial automation, embedded systems, control systems and etc. Computer-based equipment needs to be protected against unauthorized access and control. The widely accepted approach to computer security is based on security in depth, meaning that the computer system is viewed as a layered structure and security is introduced at each of the layers. In this paper, we propose a method of adding security at what is commonly viewed as the lowest level of control the PLC. The approach is based on hashing the process variables or called signals. In this approach an attacking virus is not able to interpret the variables being addressed by the control logic, and therefore inhibiting targeted attacks by a virus wishing to subtly change the controlled system operation without actually destroying the controlled plant. The approach is focused towards DCS whose operation is based on maintaining all variables in an RTDB that exist in the RTOS and used by IEC61131-3 based application.