Secure Web Access to Mini Distributed Control System

Abstract

Small distributed control systems with remote web access are
becoming fairly common. Sooner or later, security of such systems
will become a precondition for some critical applications. However,
limited computational power will require some non-standard solu-
tions. The paper describes secure web access to a prototype of small
distributed control system programmed according to IEC 61131-3
standard. Security is provided by challenge-response authentication
of web client and symmetric cryptographic primitives. Communica-
tion latency is analysed by means of a Timed Petri Net model.