Design and implementation of a secure multi-agent marketplace

A multi-agent marketplace, MAGNET (Multi AGent Negotiation Testbed), is a promising solution for conducting online combinatorial auctions. The trust model of MAGNET is somewhat different from other on-line auction systems, since the marketplace, which mediates all communications between agents, acts as a partiallytrusted third party. In this paper, we identify the security vulnerabilities of MAGNET and present a solution that overcomes these weaknesses. Our solution makes use of three different existing technologies with standard cryptographic techniques: a publish/subscribe system to provide simple and general messaging, time-release cryptography to provide guaranteed nondisclosure of the bids, and anonymous communication to hide the identity of the bidders until the end of the auction. By doing so, we successfully minimize the trust on the market as well as increase the security of the whole system. The protocol that we have developed can be adapted for use by other agent-based auction systems, which use a third party to mediate transactions.