A Novel Bidirectional Distributed Cross Domain Solution Security Architecture

With the paradigm change and the need for two-way communication and secure data transfer based on two-way correspondence between security domains with high and low information importance, the need for cross-domain solutions (CDS) has increased. The cross-domain solution is a security approach that implements data exchange between different security domains by security policies. Nowadays, distributed energy resources(DER) as a solution for small-scale power plants to produce electricity are growing more and more due to their high efficiency.Data exchange between power plants and its upstream security domain, such as the control center of the SCADA, is an inevitable necessity. To establish two-way communication, CDS equipment must follow the two-way security policy of security domains. By establishing a two-way correspondence between the high and low security domains, the CDS is able to confirm the request and the associated response and reject it otherwise. This study proposes two central ideas. The first idea proposes a two-way CDS architecture that is able to check the correspondence between the response and the received request in SCADA based on DER architecture. The second idea is a distributed CDS architecture that is able to connect several low security domains to a control center in a high security domain. Considering the large number of solar power plants as a low-security domain and how to connect them to the SCADA control center in the high-security domain, using a one-to-one architecture is a costly approach. Obviously, with the implementation of distributed architecture may lead to reduction of CDS network downtime, scalability, redundancy, flexibility, cost-effectiveness, advanced fault tolerance and preventing a single point of failure in CDS. In the current studies, there is no distributed CDS and CDS by checking two-way correspondence of packets. Therefore, in this study, a prototype of a distributed CDS architecture and two-way CDS architecture based on SCADA are proposed. By examining the two-way correspondence of packets, CDS showed a better performance in True Positive detection by $14 \%$ and eliminated False Negative detection compared to similar architectures. The total processing time of the distributed CDS architecture increased by $20 \%$ compared to the two-way CDS due to higher overheads. The results indicate that the computational overhead is cost-effective.