System information security judgment and protection method based on concurrent synthesis operator

Abstract

The invention discloses a system information security judgment and protection method based on a concurrent synthesis operator. The method is based on a brand new technology of a concurrent synthesis operator, and specifically comprises the following steps: constructing a discrete event system under an incomplete information condition as an automaton model; constructing a non-secret sub-automaton of the automaton model; in order to estimate the current state of the non-secret sub-automaton, a state observer model of the non-secret sub-automaton is given; performing concurrent synthesis operation on the original system and the state observer model of the non-secret sub-automaton to obtain an information structure based on concurrent synthesis; based on the information structure, whether the discrete event system has the strong opaque property based on the state or not can be judged, and the proposed new enhancement mechanism can protect the leaked secret state. According to the technical scheme of the invention, the verification and protection of the state-based strong opaque property of the discrete event system under the incomplete information condition are realized through a concurrent synthesis operator method.

Description

Technical Field

[0001] The present application belongs to the field of information security in system control, and specifically relates to a system information security determination and protection method based on concurrent synthesis operators. Background Art

[0002] A discrete event system is a type of man-made system that has a discrete state space and whose state evolution is triggered by discrete events, that is, the system state will only change when the driving event occurs. This is fundamentally different from a continuous variable system. In a discrete event system, the evolution of the driving state depends mainly on the occurrence of events, rather than changing over time. In a discrete event system, discrete events include external inputs, operations within the system, or any other form of discrete event activity. For example, process switching in a computer system, data transmission in a communication network, machine failure in a production process, etc.

[0003] Discrete event systems have powerful modeling capabilities and can model many complex systems generated by the integration of computing, communication and sensor technologies. At present, the analysis tools of discrete event systems come from different disciplines, including mathematics, theoretical computer science, control and system engineering, statistics, etc. In order to deeply understand, design, control and optimize discrete event systems to improve system performance and efficiency, scholars have proposed a variety of discrete event system modeling methods, including finite state automata, spiked Petri nets, Markov chains and maxima-minima algebra. The modeling technology of discrete event systems has been widely used in many fields, including computer systems, communication networks, flexible manufacturing, transportation and financial markets. In these application scenarios, through the analysis and design of discrete event systems, it is possible to effectively improve production efficiency, reduce operating costs, improve product or service quality and enhance system reliability.

[0004] With the rapid advancement of information technology and the widespread use of the Internet, people are increasingly relying on the Internet, mobile devices, and other digital tools to manage personal information and perform transactions. However, this reliance on digital information technology has also brought new security and privacy challenges, such as cyber attacks, data leaks, and identity theft. The frequent occurrence of these security incidents has caused significant losses not only to individuals and businesses, but also to the country. Therefore, it has become crucial to ensure that the system does not leak its sensitive information during operation, which requires continuous reinforcement and updating of the security of the system model. Therefore, how to determine whether the system security information has been leaked to external intruders and how to protect the system secret information when the secret information is exposed has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] Based on the above problems, this application provides a system information security judgment and protection method based on concurrent composition operators. The purpose is to determine whether the discrete event system has successfully protected the state-based secret information. When the system fails to protect the secret information, a new reinforcement mechanism is proposed to protect the original system secret information.

[0006] The embodiments of the present application disclose the following technical solutions:

[0007] Firstly, the discrete event system under the condition of incomplete information to be judged is modeled as an automaton model;

[0008] Secondly, the secret state and its associated event-labeled transitions in the automaton model are deleted to obtain a non-secret sub-automaton model of the discrete event system under the incomplete information condition;

[0009] Thirdly, performing state estimation on the non-secret sub-automaton model to obtain a state observer model of the non-secret sub-automaton;

[0010] Finally, performing concurrent synthesis operation on the automaton model and the state observer model of the non-secret sub-automaton to obtain a concurrent synthetic automaton structure;

[0011] Based on the concurrent synthetic automaton structure, verify whether the discrete event system under the incomplete information condition to be determined has a state-based strong opaque property;

[0012] When the discrete event system under the incomplete information condition has a strong state-based opaque property, it means that the original system has achieved the protection of secret information;

[0013] When the discrete event system under the incomplete information condition does not have a strong state-based opaque property, a new opacity enhancement mechanism is designed to modify and restrict the behavior of the original system, thereby achieving the protection of the system's secret information.

[0014] Correspondingly, the expression of the automaton model is specifically: G=(X,∑,δ,X0,X S ); Among them, X is a finite state set, ∑ is a finite event set, X0 is the initial state set, X S is the specified secret state set, δ:X×∑→2 X is a local transition function, and the δ is used to describe the dynamic evolution behavior of the automaton G.

[0015] Correspondingly, the expression of the non-secret sub-automaton model is specifically: G dss =(X dss ,∑dss , δ dss ,X dss,0 ); Among them, X dss is a finite state set, ∑ dss is a finite set of events, X dss,0 is the initial state set, is the local transition function, the δ dss Used to describe a non-secret subautomaton G dss Dynamic evolution behavior.

[0016] Correspondingly, the state observer model of the non-secret sub-automaton model is obtained by performing state estimation on the non-secret sub-automaton model as follows: in, is the state set, is a set of observable events, is the initial state set, is the local transition function, Used to describe the observer Obs(G dss )’s dynamic evolution behavior.

[0017] Correspondingly, the expression of the concurrent synthesis automaton structure is specifically: Cc(G,Obs(G dss ))=(X CC ,∑ cc, δ cc , X cc,0 ) Among them, Cc represents concurrent composition operation, is a finite state set, ∑ cc ={(σ,σ):σ∈∑ o}∪{(σ,ε):σ∈∑ uo} is a finite set of events, is the local transition function, is the initial state set.

[0018] Correspondingly, the method of verifying whether the discrete event system under the condition of incomplete information to be determined has a strong opaque property based on the state based on the concurrent synthetic automaton structure comprises: the discrete event system under the condition of incomplete information to be determined has a strong opaque property based on the state if and only if there is no corresponding leaked secret state in the concurrent synthetic automaton structure, that is, in Cc(G,Obs(G dss )) does not exist in the form The state where x∈X S .

[0019] Accordingly, the new opacity enhancement mechanism includes: before the original system starts running, selecting a concurrent synthesis structure Cc(G,Obs(G dss The last controllable transition in all operations that expose the secret state in )) is invalid (if any), so as to protect the secret information of the original system. The premise of the opacity enhancement mechanism is that the structure of the original system is known and the transition with events is locally controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flowchart of a discrete event system information security determination and protection method under incomplete information conditions provided by this application;

[0021] Figure 2 A schematic diagram of an automaton model of a discrete event system under incomplete information conditions provided in an embodiment of the present application;

[0022] Figure 3 A schematic diagram of a non-secret sub-automaton model provided in an embodiment of the present application;

[0023] Figure 4 A schematic diagram of a state observer model of a non-secret sub-automaton provided in an embodiment of the present application;

[0024] Figure 5 A schematic diagram of a concurrent synthesis automaton structure provided in an embodiment of the present application. Specific implementation methods

[0025] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] A discrete event system is modeled as a finite state automaton G = (X, ∑, δ, X0, X S ), where X is a finite state set, ∑ is a finite event set, X0 is an initial state set, is the secret state set, δ:X×∑→2 Xis a local state transition function, which is used to describe the dynamic evolution behavior of the automaton: for state x, y∈X, event σ∈∑, y∈δ(x,σ) means that when event σ occurs, the state x of the automaton reaches state y after event σ. Based on the sensor limitations on the attached system and the distributed nature of the system, the intruder can only see the local behavior of the system. Therefore, the event set ∑ is divided into the observable event set ∑ o (events visible to the intruder) and the set of unobservable events ∑ uo (events that the intruder cannot see), that is, ∑ o ∪∑ uo =∑ and For this reason, natural projection The recursive definition is: Among them, s∈∑ * And s∈∑. Such a system G is called a discrete event system under incomplete information conditions. A run of the system G is called non-secret if it does not pass through any secret state.

[0027] In a discrete event system based on a finite state automaton model, based on the distributed characteristics of the system and the unpreventable characteristics of some events, the system event set is divided into a controllable event set ∑ c and the set of uncontrollable events∑ uc , that is, ∑=∑ c ∪∑ uc Specifically, the controller may fail c The controllable events in the controllable event list are used to restrict the behavior of the system (if feasible) so that it can perform the predetermined legal behavior, thereby achieving effective control over the behavior of the system. However, uncontrollable events are those that cannot be prevented by the monitor. In other words, the controller cannot prevent the occurrence of uncontrollable events by failure. uc to constrain system behavior based on events in the

[0028] In one example implementation, the state-based strong opacity property is characterized as strong current-state opacity, which is formally defined as follows:

[0029] Given a discrete event system G = (X, ∑, δ, X0, X S ) and the set of observable events The natural projection P of x S ∈X S , there exists a corresponding non-secret operation If x∈X, such that P(t)=P(s), then the system G is said to have the strong current-state opacity property.

[0030] See also Figure 1, which is a flowchart of a discrete event system information security determination and protection method under incomplete information conditions provided by an embodiment of the present application. The method includes the following steps:

[0031] Step S1: A discrete event system construction automaton model under incomplete information conditions is given; G=(X,∑,δ,X0,X S ), Among them, X is a finite state set, ∑ is a finite event set, X0 is the initial state set, X S is the specified secret state set, δ:X×∑→2 X is the local transition function, and δ is used to describe the dynamic evolution behavior of system G.

[0032] Step S2: The non-closed subautomaton model of system G is given: G dss =(X dss ,∑ dss , δ dss , X dss,0 ), Among them, X dss is a finite state set, ∑ dss is a finite set of events, X dss,0 is the initial state set, is the local transition function, δ dss Used to describe the dynamic evolution behavior of non-secret subautomata.

[0033] Step S3: Construct the state observer of the non-secret subautomaton: in, is the state set, is a set of observable events, is the only initial state, is a local transition function, which is used to describe the dynamic evolution behavior of the state observer.

[0034] Step S4: define the state observer Obs(G dss ) Concurrent synthesis operation: Cc(G,Obs(G dss ))=(X CC ,∑ cc , δ cc , X cc,0 ) in, is a finite state set, ∑ cc ={(σ,σ):σ∈∑ o}∪{(σ,ε):σ∈∑ uo} is a finite set of events, is the local transition function, is the initial state set.

[0035] Based on the concurrent synthesis structure Cc(G,Obs(G dss ), step S5 gives the necessary and sufficient conditions for whether the discrete event system under incomplete information conditions has the state-based strong current opacity property: the system G has the state-based strong opacity if and only if the concurrent composition structure Cc(G, Obs(G dss )) There is no leaked secret state. When the system has strong state-based opacity, the process ends, otherwise execute step S6.

[0036] Through step S6, the concurrent synthesis structure Cc(G, Obs(G dss )) in all operations that expose the secret state are invalidated in order to cut off all operations that violate the strong opacity of the state, thereby achieving the protection of the secret information of the original system.

[0037] In an exemplary implementation, according to step S1 of the flowchart, the discrete event system under the condition of incomplete information is respectively as follows: Figure 2 As shown. Figure 2 In the above equation, X0={0,1}, X S ={1,5,9},∑ o ={a, b},∑ uo ={u,v},∑ c ={a,u,v},∑ uc ={b}.

[0038] According to step S2 of the flowchart, construct Figure 2 Non-secret subautomaton model of the system shown G dss =(X dss ,∑ dss , δ dss ,X dss，0 ) like Figure 3 As shown. Figure 3 In, X dss,0 ={0},∑ dss ={a, b, u}.

[0039] According to step S3 of the flowchart, we get the non-secret sub-automaton G dss State Observer like Figure 4 shown.

[0040] According to step S4 of the flowchart, the original system G is combined with the non-secret sub-automaton observer Obs(G dss ) performs concurrent synthesis operations to obtain a concurrent synthesis structure Cc(G,Obs(G dss ))=(X CC ,∑ cc ,δ cc ,X cc,0 ) like Figure 5 (a) shown.

[0041] According to step 5 of the flowchart, use Figure 5 (a) shows the concurrent synthesis structure Cc(G, Obs(G dss )),determination Figure 2 Whether the system shown has strong current-state opacity.

[0042] exist Figure 5 In (a), there is a leaked secret state where state 9∈X S .therefore, Figure 2 The system shown does not have a strong current state opacity property. Execute step S6.

[0043] According to step 6 of the flowchart, in order to prevent Cc(G, Obs(G dss )) in the leaked state Generate, choose from the initial state (0, {0, 2}) to reach the leak state The last controllable transition in the operation of Failure, which is equivalent to the controllable transition of the failed original system G In this way, a new concurrent synthesis structure can be obtained like Figure 5 (b) is shown. Similarly, in order to prevent The leak status in Generate (i.e. prevent system G 1 The secret state 5 is leaked), select the failure controllable transition and Get concurrent synthesis structure if Figure 5 (c) is shown. There is no form of (where x∈X S ) is leaked. Therefore, the protection of the secret state information of the original system G is achieved.

[0044] In the embodiment of the present application, information security determination and protection of discrete event systems under incomplete information conditions are achieved based on concurrent synthesis operator technology.

Claims

1. A system information security determination and protection method based on concurrent synthesis operator, characterized in that: Based on concurrent synthesis technology, the method includes: Modeling a discrete event system under incomplete information conditions to be determined as an automaton model, wherein the discrete event system under incomplete information conditions to be determined contains secret information that needs to be protected, and the secret information refers to a secret state in the automaton model; Deleting the secret state and its associated event-labeled transitions in the automaton model to obtain a non-secret sub-automaton model of the discrete event system under the incomplete information condition; Performing state estimation on the non-secret sub-automaton model to obtain a state observer model of the non-secret sub-automaton; Performing concurrent synthesis operation on the automaton model and the state observer model of the non-secret sub-automaton to obtain a concurrent synthetic automaton structure; Based on the concurrent synthetic automaton structure, verify whether the discrete event system under the incomplete information condition to be determined has a state-based strong opaque property; If the discrete event system under the incomplete information condition has a strong state-based opaque property, it indicates that the secret information of the discrete event system is secure; If the discrete event system under the incomplete information condition does not have a strong state-based opacity property, a new opacity enhancement mechanism is proposed, which disables certain controllable changes before the original system starts running, thereby protecting the secret information security of the discrete event system.

2. The method according to claim 1, characterized in that The expression of the automaton model is specifically: G=(X,Σ,δ,X0,X S ); Among them, X is a finite state set, ∑ is a finite event set, X0 is the initial state set, X S is the specified secret state set, δ:X×∑→2 X is a local transition function, and the δ is used to describe the dynamic evolution behavior of the automaton G.

3. The method according to claim 1, characterized in that The non-secret sub-automaton model expression is specifically: G dss =(X dss ,∑ dss ,δ dss ,X dss,0 ); Among them, X dss is a finite state set, ∑ dss is a finite set of events, X dss,0 is the initial state set, is the local transition function, the δ dss Used to describe a non-secret subautomaton G dss Dynamic evolution behavior.

4. The method according to claim 1, characterized in that The state observer model of the non-secret sub-automaton model obtained by performing state estimation on the non-secret sub-automaton model is specifically: in, is the state set, is a set of observable events, is the initial state set, is the local transition function, Used to describe the observer Obs(G dss )’s dynamic evolution behavior.

5. The method according to claim 1, characterized in that The concurrent synthesis automaton structure expression is specifically: Cc(G,Obs(G dss ))=(X CC ,∑ cc ,δ cc ,X cc,0 ) Among them, Cc represents concurrent composition operation, is a finite state set, ∑ cc ={(σ,σ):σ∈∑ o }∪{(σ,ε):σ∈∑ uo } is a finite set of events, is the local transition function, is the initial state set.

6. The method according to claim 1, characterized in that The step of verifying whether the discrete event system under the incomplete information condition to be determined has a state-based strong opaque property based on the concurrent synthetic automaton structure includes: The discrete event system under the condition of incomplete information to be determined has a strong state-based opaque property if and only if there is no corresponding leaked secret state in the concurrent synthetic automaton structure, that is, in Cc(G, Obs(G dss )) does not exist in the form The state where x∈X S .

7. The method according to claim 1, characterized in that The described state-based strong opacity protection method is based on a new strengthening mechanism, including: Before the original system starts running, select the concurrent synthesis structure Cc(G, Obs(G dss The last controllable transition in all operations that expose the secret state in )) is invalid (if any), so as to protect the secret information of the original system. The premise of the opacity enhancement mechanism is that the structure of the original system is known and the transition with events is locally controllable.

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