Automatic Fair Exchanges

TL;DR

This paper introduces MuAC, a policy language enabling automated, fair resource exchanges in decentralized systems, ensuring mutual satisfaction and preventing cheating, demonstrated through a blockchain NFT exchange application.

Contribution

The paper presents MuAC, a novel policy language for automated fair exchanges that guarantees mutual agreement and can enforce honest behavior in decentralized environments.

Findings

MuAC ensures only mutually satisfying exchanges occur.

Implementation of MuAC as a blockchain smart contract for NFT trading.

MuAC effectively prevents cheating in resource exchanges.

Abstract

In a decentralized environment, exchanging resources requires users to bargain until an agreement is found. Moreover, human agreements involve a combination of collaborative and selfish behavior and often induce circularity, complicating the evaluation of exchange requests. We introduce MuAC, a policy language that allows users to state in isolation under which conditions they are open to grant their resources and what they require in return. In MuAC, exchange requests are evaluated automatically with the guarantee that the only exchanges that will take place are those that mutually satisfy users' conditions. Moreover, MuAC can be used as an enforcement mechanism to prevent users from cheating. As a proof of concept, we implement a blockchain smart contract that allows users to exchange their non-fungible tokens.