ARA: a robust audit to prevent free-riding in P2P networks

A number of solutions have been proposed to address the free-riding problem in peer-to-peer file sharing systems. The solutions are either imperfect-they allow some users to cheat the system with malicious behavior, or expensive-they require human intervention, require servers, or incur high mental transaction costs. The authors proposed a method to address these weaknesses. Specifically, a utility function was introduced to capture contributions made by a user and an auditing scheme to ensure the integrity of a utility function´s values. The method enabled to reduce cheating by a malicious peer: it is shown that this approach can efficiently detect malicious peers with a probability over 98%.