A system information security judgment and protection method based on concurrent composition operator

Abstract

This application discloses a method for determining and protecting system information security based on concurrent composition operators. This method, based on the novel technology of concurrent composition operators, specifically includes: constructing an automaton model of a discrete event system under incomplete information conditions; constructing a non-secret subautomaton of the automaton model; providing a state observer model of the non-secret subautomaton to estimate its current state; performing concurrent composition operations on the original system and the state observer model of the non-secret subautomaton to obtain an information structure based on concurrent composition; and, based on this information structure, determining whether the discrete event system possesses a state-based strong opacity property, with the proposed new enhancement mechanism protecting the leaked secret state. The technical solution of this application, through the concurrent composition operator method, achieves the verification and protection of the state-based strong opacity property of discrete event systems under incomplete information conditions.

Description

Technical Field

[0001] This application belongs to the field of information security in system control, specifically involving a method for determining and protecting system information security based on concurrent composite operators. Background Technology

[0002] Discrete-event systems are a class of artificial systems with discrete state spaces, where state evolution is driven and triggered by discrete events. That is, the system state only changes at the instant the driving event occurs. This is fundamentally different from continuous-variable systems. In discrete-event systems, the evolution of the driving state depends primarily on the occurrence of the event, rather than changing over time. Discrete events in discrete-event systems include external inputs, internal system operations, or any other form of discrete event activity. Examples include process switching in a computer system, data transmission in a communication network, and machine failures in a production process.

[0003] Discrete event systems (DIS) possess powerful modeling capabilities, enabling the modeling of numerous complex systems arising from the integration of computing, communication, and sensing technologies. Currently, analytical tools for DIS come from diverse disciplines, including mathematics, theoretical computer science, control and systems engineering, and statistics. To gain a deeper understanding, design, control, and optimization of DIS to improve system performance and efficiency, researchers have proposed various modeling methods, including finite state automata, scaled Petri nets, Markov chains, and minimax-minimax algebras. DIS modeling techniques have been widely applied in numerous fields, including computer systems, communication networks, flexible manufacturing, transportation, and financial markets. In these applications, the analysis and design of DIS can effectively improve production efficiency, reduce operating costs, enhance product or service quality, and increase system reliability.

[0004] With the rapid advancement of information technology and the widespread use of the internet, people are increasingly reliant on the internet, mobile devices, and other digital tools to manage personal information and conduct transactions. However, this dependence on digital information technology has also brought new security and privacy challenges, such as cyberattacks, data breaches, and identity theft. The frequent occurrence of these security incidents has caused significant losses not only to individuals and businesses but also to nations. Therefore, ensuring that systems do not leak their sensitive information during operation has become crucial, requiring continuous hardening and updating of system model security. Consequently, how to determine whether system security information has been leaked to external intruders and how to protect confidential system information when it is exposed have become urgent technical problems that need to be solved. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a method for determining and protecting system information security based on concurrent composition operators. The aim is to determine whether a discrete event system has successfully protected state-based secret information. When the system fails to protect the secret information, a new enhancement mechanism is proposed to protect the original system's secret information.

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

[0007] First, the discrete event system under the condition of incomplete information to be determined is modeled as an automata model;

[0008] Secondly, the secret states and their associated marked event transitions in the automaton model are deleted to obtain the non-secret subautomaton model of the discrete event system under the condition of incomplete information.

[0009] Next, state estimation is performed on the non-secret sub-automata model to obtain the state observer model of the non-secret sub-automata;

[0010] Finally, concurrent synthesis operations are performed on the automaton model and the state observer model of the non-secret subautomaton to obtain the concurrent synthesis automaton structure;

[0011] Based on the concurrent synthetic automata structure, it is verified whether the discrete event system under the condition of incomplete information to be determined has a state-based strong opacity property.

[0012] When the discrete event system under the condition of incomplete information has a strong state-based opacity, it indicates that the original system has achieved protection of secret information.

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

[0014] Accordingly, the expression for the automata model is specifically as follows:

[0015] G = (X, ∑, δ, X0, X) S );

[0016] Where X is a finite set of states, ∑ is a finite set of events, X0 is the initial set of states, and X S For a given set of secret states, δ: X×∑→2 X δ is a local transition function, used to describe the dynamic evolution behavior of the automaton G.

[0017] Accordingly, the expression for the non-secret subautomata model is specifically as follows:

[0018] Gdss =(X dss ,∑ dss δ dss ,X dss,0 );

[0019] Among them, X dss For a finite set of states, ∑ dss For a finite set of events, X dss,0 For the initial state set, For local transition functions, the δ dss Used to describe non-secret subautomata G dss The dynamic evolutionary behavior.

[0020] Accordingly, the process of performing state estimation on the non-secret sub-automaton model to obtain the state observer model of the non-secret sub-automaton is specifically as follows:

[0021]

[0022] in, It is a set of states. A considerable set of events, For the initial state set, For local transition functions, the Used to describe the observer Obs(G) dss The dynamic evolutionary behavior of ).

[0023] Accordingly, the expression for the concurrent synthesis automaton structure is specifically as follows:

[0024] Cc(G,Obs(G dss ))=(X CC , ∑ cc, δ cc X cc,0 )

[0025] Where Cc represents concurrent composition operation, For a finite set of states, ∑ cc ={(σ, σ): σ∈∑ o}∪{(σ,ε):σ∈∑ uo} is a finite set of events. For local transition functions, This is the initial state set.

[0026] Accordingly, the verification of whether the discrete event system under the condition of incomplete information to be determined has a state-based strong opacity property based on the concurrent synthesis automaton structure includes: the discrete event system under the condition of incomplete information to be determined has a state-based strong opacity property if and only if there is no corresponding secret state in the concurrent synthesis automaton structure, that is, in Cc(G,Obs(G) dss The form )) does not exist in The state where x∈X S .

[0027] Accordingly, the novel opacity enhancement mechanism includes: selecting a concurrent synthesis structure Cc(G,Obs(G) before the original system starts running. dss The last controllable transition in all operations that exposes the secret state fails (if it exists), thus protecting the secret information of the original system. The prerequisite for this opacity enhancement mechanism is that the structure of the original system is known and the transitions involving events are locally controllable. Attached Figure Description

[0028] Figure 1 A flowchart illustrating a method for determining and protecting information security in a discrete event system under incomplete information conditions, as provided in this application;

[0029] Figure 2 A schematic diagram of an automata model of a discrete event system under incomplete information conditions is provided for an embodiment of this application.

[0030] Figure 3 A schematic diagram of a non-secret subautomata model provided in an embodiment of this application;

[0031] Figure 4 A schematic diagram of a state observer model for a non-secret subautomata provided in this application embodiment;

[0032] Figure 5 This is a schematic diagram of a concurrent synthetic automaton structure provided in an embodiment of this application. Specific implementation methods

[0033] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0034] A discrete event system is modeled as a finite state automaton G = (X, ∑, δ, X0, X...) S ), where X is a finite set of states, ∑ is a finite set of events, and X0 is the initial set of states. Let δ be the set of secret states: X×∑→2 X Let be the local state transition function, used to describe the dynamic evolution behavior of the automaton: for states x, y ∈ X, event σ ∈ ∑, y ∈ δ(x, σ) indicates that when event σ occurs, the automaton's state x reaches state y after event σ. Due to the sensor limitations on the dependent system and the distributed nature of the system, an intruder can only observe 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), i.e., ∑ o ∪∑ uo =∑and Therefore, natural projection Recursion is defined as:

[0035]

[0036] Where, s∈∑ * And s∈∑. Such a system G is called a discrete-event system under incomplete information conditions. A run of system G is called non-secret if it does not pass through any secret states.

[0037] In a discrete event system based on a finite state automaton model, given the system's distributed nature and the unpredictable nature of certain events, the system event set is divided into a controllable event set ∑. c and uncontrollable event set ∑ uc That is, ∑=∑ c ∪∑ uc Specifically, the controller can fail. c Controllable events in a system can be used to constrain its behavior (if feasible) and force it to perform predetermined legal actions, thereby achieving effective control over the system's behavior. However, uncontrollable events are those that cannot be prevented from occurring by the monitor; in other words, the controller cannot prevent them from happening through failures. uc Events in the system are used to limit system behavior.

[0038] In one example implementation, the state-based strong opacity property is characterized as strong current state opacity, which is formally defined as follows:

[0039] Given a discrete event system G = (X, ∑, δ, X0, X...) under conditions of incomplete information. S and observable event set The natural projection P, if for any running 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 strong current state opacity.

[0040] See Figure 1 This figure is a flowchart illustrating a method for determining and protecting information security in a discrete event system under incomplete information conditions, as provided in an embodiment of this application. The method includes the following steps:

[0041] Step S1: An automata model for a discrete event system under incomplete information conditions is given;

[0042] G = (X, ∑, δ, X0, X) S ),

[0043] Where X is a finite set of states, ∑ is a finite set of events, X0 is the initial set of states, and X S For a given set of secret states, δ: X×∑→2 X δ is a local transition function used to describe the dynamic evolution behavior of system G.

[0044] Step S2: The non-mist automaton model of system G is given:

[0045] G dss =(X dss , ∑ dss δ dss X dss,0 ),

[0046] Among them, X dss For a finite set of states, ∑ dss For a finite set of events, X dss,0 For the initial state set, For local transition functions, δ dss It is used to describe the dynamic evolutionary behavior of non-secret subautomata.

[0047] Step S3: A state observer for the non-secret subautomaton was constructed:

[0048]

[0049] in, It is a set of states. A considerable set of events, As a unique initial state, This is a local transition function used to describe the dynamic evolution behavior of the state observer.

[0050] Step S4: Define the state observer Obs(G) of the system G and the non-secret subautomata. dss Concurrent composition operations:

[0051] Cc(G,Obs(G dss ))=(X CC , ∑ cc δ cc X cc,0 )

[0052] in, For a finite set of states, ∑ cc ={(σ, σ): σ∈∑ o}∪{(σ,ε):σ∈∑ uo} is a finite set of events. For local transition functions, This is the initial state set.

[0053] Based on the concurrent synthesis structure Cc(G,Obs(G) dss Step S5 gives the necessary and sufficient condition for whether a discrete event system under incomplete information conditions has a strong state-based opacity: the system G has strong state-based opacity if and only if the concurrent composition structure Cc(G, Obs(G)) is equal to the state-based structure Cc(G, Obs(G)). dss There is no leaked secret state in the process. The process ends when the system has strong state-based opacity; otherwise, proceed to step S6.

[0054] In step S6, the concurrent synthesis structures Cc(G, Obs(G) are selected. dss The last controllable transition in all operations that expose the secret state fails, thereby cutting off all operations that violate the strong opacity property based on state, thus protecting the secret information of the original system.

[0055] In one example implementation, according to flowchart step S1, the discrete event system under incomplete information conditions is as follows: Figure 2 As shown. In Figure 2 In the given information, X0 = {0, 1}, X S ={1, 5, 9}, ∑ o ={a, b}, ∑ uo ={u,v},∑ c ={a,u,v},∑ uc ={b}.

[0056] Based on step S2 of the flowchart, construct... Figure 2 The non-secret subautomata model of the system shown

[0057] G dss =(X dss ,∑ dssδ dss ,X dss，0 )

[0058] like Figure 3 As shown. In Figure 3 In the middle, X dss,0 ={0}, ∑ dss = {a, b, u}.

[0059] According to step S3 of the flowchart, the non-secret subautomaton G is obtained. dss State observer

[0060]

[0061] like Figure 4 As shown.

[0062] According to step S4 of the flowchart, the original system G and the non-secret subautomaton observer Obs(G) are connected. dss Perform concurrent composition operations to obtain the concurrent composition structure.

[0063] Cc(G,Obs(G dss ))=(X CC , ∑ cc ,δ cc ,X cc,0 )

[0064] like Figure 5 As shown in (a).

[0065] According to step 5 of the flowchart, using Figure 5 (a) shows the concurrent synthesis structure Cc(G, Obs(G) dss )),determination Figure 2 Does the system shown have a strong current state opacity property?

[0066] 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. Proceed to step S6.

[0067] According to step 6 of the flowchart, in order to prevent Cc(G, Obs(G) from being blocked... dss The state of leakage in )) Generate, select from the initial state (0, {0, 2}) to reach the leak state. The last controllable transition in operation Failure is equivalent to the failure of the controllable transitions of the original system G. In this way, a new concurrent synthesis structure can be obtained. like Figure 5As shown in (b). Similarly, in order to prevent The state of leakage in Generate (i.e. prevent system G) 1 (Secret state 5 leaked), selectable failure controllable transition and Obtain concurrent synthesis structure if Figure 5 As shown in (c). In In, there is no form of (where x∈X) S This prevents the leakage of the secret state of the original system G. Therefore, the protection of the secret state information of the original system G is achieved.

[0068] In this embodiment, the information security determination and protection of discrete event systems under incomplete information conditions is realized based on the concurrent synthesis operator technology.

Claims

1. A method for determining and protecting system information security based on concurrent composition operators, characterized in that, Based on concurrent synthesis technology, the method includes: The discrete event system under incomplete information conditions to be determined is modeled as an automaton model. The discrete event system under incomplete information conditions to be determined contains secret information that needs to be protected. The secret information refers to the secret state in the automaton model. By removing the secret states and their associated labeled event transitions from the automaton model, a non-secret subautomaton model of the discrete event system under the condition of incomplete information is obtained. The specific expression of the non-secret subautomaton model is as follows: G dss =(X dss ,S dss ,d dss ,X dss,0 ); Among them, X dss For a finite set of states, Σ dss For a finite set of events, X dss,0 For the initial state set, For local transition functions, the δ dss Used to describe non-secret subautomata G dss The dynamic evolutionary behavior; State estimation is performed on the non-secret subautomaton model to obtain the state observer model of the non-secret subautomaton. The specific expression of the state observer model of the non-secret subautomaton is as follows: in, It is a set of states. A considerable set of events, For the initial state set, For local transition functions, the Used to describe the observer Obs(G) dss The dynamic evolutionary behavior of ); Concurrent synthesis operations are performed on the automaton model and the state observer model of the non-secret subautomaton to obtain the concurrent synthesis automaton structure; Based on the concurrent synthetic automata structure, it is verified whether the discrete event system under the condition of incomplete information to be determined has a state-based strong opacity property. If the discrete event system under the condition of incomplete information has a strong state-based opacity, it indicates that the secret information of the discrete event system is secure. If the discrete event system under the condition of incomplete information does not have a strong state-based opacity, a new opacity enhancement mechanism is proposed, which disables certain controllable transitions before the original system starts running, thereby protecting the security of the secret information of the discrete event system.

2. The method according to claim 1, characterized in that, The specific expression for the automata model is as follows: G=(X,∑,δ,X0,X S ); Where X is a finite set of states, ∑ is a finite set of events, X0 is the initial set of states, and X S For the specified set of secret states, δ: X×∑→2 X δ is a local transition function, used to describe the dynamic evolution behavior of the automaton G.

3. The method according to claim 1, characterized in that, The specific structural expression of the concurrent synthetic automaton is as follows: Cc(G,Obs(G dss ))=(X CC ,S cc ,d cc ,X cc,0 ) Where Cc represents concurrent composition operation, For a finite set of states, Σ cc ={(σ,σ):σ∈Σ o }∪{(σ,∈):σ∈Σ uo } is a finite set of events. For local transition functions, This is the initial state set.

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

5. The method according to claim 1, characterized in that, The state-based strong opacity protection method described above is based on a novel reinforcement 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 exposes the secret state in the process fails, thereby protecting the secret information of the original system; wherein, the prerequisite for 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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