Secure network of safety plcs for industrial plants

Abstract

Network of safety PLCs employs multi-PLC verification of a programming application before allowing the application to reprogram any PLC on the safety network. Each PLC on the safety network is equipped with authentication capability that detects attempts to reprogram the PLC and issues an authentication challenge requiring the programming application to process a proof-of-work. The authentication challenge is also sent to other PLCs on the safety network along with the response from the programming application for verification purposes. The other PLCs process the authentication challenge and check the response from the programming application for acceptability. If a majority of the PLCs on the safety network determines the response from the programming application is correct, then the programming application is verified and may proceed with the reprogramming. Such group authentication requires a malicious application to hijack multiple PLCs concurrently on the safety network, a highly unlikely outcome, before reprogramming any PLC.

Dependencies are inferred from the claim text.