Protection Efficiency Evaluation for Blockchain-Based Subsytems of a Smart City

An unclear security perimeter, low level of end node security, combined with the increased activity of intruders using advanced techniques to bypass security systems, significantly complicate the task of ensuring cybersecurity of blockchain-based digital infrastructures on smart city. To reduce cyber risks affecting smart city, various protection mechanisms with configured rules for correlating events in the distributed digital infrastructure are used. However, due to the dynamics of the protected object and the rapidly changing landscape of cyberthreats, assessing the effectiveness of the defense mechanisms and selecting the optimal configuration is a complex task. This paper presents a developed mathematical model of cybersecurity event management using a continuous-time Markov chain, within which the problem to be solved is to prevent the system from transitioning from the state of “a cybersecurity event occurred” to the state of “a cybersecurity incident occurred” due to high accuracy and speed of detection and response to the event. This paper also presents a developed model of the cyberattack propagation in blockchain-based subsystems of a smart city based on the extension of the traditional predator-prey model, within which a criterion of adequacy of applied protective mechanisms to the changing parameters of the smart city system and current cyberthreats is proposed. The experimental study has confirmed prospects of the suggested solution in assessing the effectiveness and selecting the optimal configuration of the protection system.