Modal Logic for Distributed Trust

TL;DR

This paper introduces a modal logic framework for reasoning about trust in multi-agent distributed systems, enabling formal analysis of communication, trust assumptions, and their propagation across networks.

Contribution

It develops a modal logic language for modeling trust and communication in multi-agent systems, including trust chains and adaptable proof systems.

Findings

Formal modal logic for trust reasoning in networks

Modeling trust propagation through nested modalities

Application to public key infrastructure and distributed protocols

Abstract

We propose a method for reasoning about trust in multi-agent systems, specifying a language for describing communication protocols and making trust assumptions and derivations. This is given an interpretation in a modal logic for describing the beliefs and communications of agents in a network. We define how information in the network can be shared via forwarding, and how trust between agents can be generalized to trust across networks. We give specifications for the modal logic which can be readily adapted into a lambda calculus of proofs. We show that by nesting modalities, we can describe chains of communication between agents, and establish suitable notions of trust for such chains. We see how this can be applied to trust models in public key infrastructures, as well as other interaction protocols in distributed systems.