Security model for a multi-agent marketplace

A multi-agent marketplace, MAGNET (Multi AGent Negotiation Testbed), is a promising solution to conduct online combinatorial auctions. The trust model of MAGNET is somewhat different from other on-line auction systems: the mediated marketplace is a partially-trusted 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 other standard cryptographic techniques: publish/subscribe systems that provide simple and more 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.