Certifiably Robust Policy Learning against Adversarial Communication in Multi-agent Systems
This addresses safety issues for deploying communicative agents in real-world applications where attackers may manipulate messages, though it is incremental as it builds on existing MARL frameworks.
The paper tackles the problem of adversarial communication in multi-agent reinforcement learning by proposing a certifiable defense that aggregates ablated message sets, ensuring agents benefit from benign communication while remaining robust to attacks, with experiments showing significant robustness improvements.
Communication is important in many multi-agent reinforcement learning (MARL) problems for agents to share information and make good decisions. However, when deploying trained communicative agents in a real-world application where noise and potential attackers exist, the safety of communication-based policies becomes a severe issue that is underexplored. Specifically, if communication messages are manipulated by malicious attackers, agents relying on untrustworthy communication may take unsafe actions that lead to catastrophic consequences. Therefore, it is crucial to ensure that agents will not be misled by corrupted communication, while still benefiting from benign communication. In this work, we consider an environment with $N$ agents, where the attacker may arbitrarily change the communication from any $C<\frac{N-1}{2}$ agents to a victim agent. For this strong threat model, we propose a certifiable defense by constructing a message-ensemble policy that aggregates multiple randomly ablated message sets. Theoretical analysis shows that this message-ensemble policy can utilize benign communication while being certifiably robust to adversarial communication, regardless of the attacking algorithm. Experiments in multiple environments verify that our defense significantly improves the robustness of trained policies against various types of attacks.