How can we ensure the security and privacy of multi-agent systems in adversarial settings?

1 Threat models

The first step to design secure and private MAS is to identify and analyze the possible threat models that they may encounter. A threat model is a representation of the capabilities, objectives, and strategies of an adversary that can harm the MAS or its agents. For example, an adversary may try to intercept, modify, or block the communication between agents, to gain access to their data or resources, to influence their behavior or decisions, or to disrupt their functionality or performance. Depending on the nature and level of the threat, different security and privacy requirements and countermeasures may be needed.

2 Communication security

One of the most important aspects of MAS security is to ensure the confidentiality, integrity, and availability of the communication between agents. Confidentiality means that only authorized agents can access the messages exchanged by the MAS, integrity means that the messages are not altered or corrupted by the adversary, and availability means that the messages are delivered without delays or losses. To achieve communication security, MAS can use techniques such as encryption, authentication, digital signatures, and secure routing protocols. These techniques can prevent or detect attacks such as eavesdropping, tampering, spoofing, or denial-of-service.

4 Agent security

A third aspect of MAS security is to ensure the safety and reliability of the agents themselves. Agent security means that the agents can resist or recover from attacks that target their hardware, software, or logic. For example, an adversary may try to hack, damage, or compromise an agent, to inject malicious code or data, to alter its configuration or parameters, or to manipulate its beliefs or goals. To achieve agent security, MAS can use techniques such as intrusion detection and prevention, self-healing and adaptation, verification and validation, or trust and reputation. These techniques can help the agents to identify and respond to attacks such as malware, sabotage, or subversion.

5 Coordination security

A fourth aspect of MAS security is to ensure the effectiveness and efficiency of the coordination mechanisms that they use to achieve their goals. Coordination security means that the agents can cooperate, negotiate, or compete with each other in a fair and rational way, without being deceived or exploited by the adversary. For example, an adversary may try to disrupt, interfere, or influence the coordination protocols, to create conflicts or coalitions, to cheat or lie, or to free-ride or defect. To achieve coordination security, MAS can use techniques such as game theory, mechanism design, contract theory, or social choice theory. These techniques can help the agents to design and implement secure and robust coordination schemes.

6 Privacy-preserving learning

A fifth aspect of MAS security is to ensure the privacy of the learning processes that they use to improve their performance and adapt to changing environments. Privacy-preserving learning means that the agents can learn from their own or other agents' data or experiences, without revealing sensitive or confidential information to the adversary. For example, an adversary may try to access, analyze, or modify the data or models that the agents use to learn, to infer their strategies or weaknesses, to bias their outcomes, or to steal their intellectual property. To achieve privacy-preserving learning, MAS can use techniques such as homomorphic encryption, secure multiparty computation, federated learning, or differential privacy. These techniques can enable the agents to learn securely and collaboratively.