Solving fair exchange with mobile agents

Mobile agents have been advocated to support electronic commerce over the Internet. While being a promising paradigm, many intricate problems need to be solved to make this vision reality. The problem of fair exchange between two agents is one such fundamental problem, Informally speaking, this means to exchange two electronic items in such a way that neither agent suffers a disadvantage. We study the problem of fair exchange in the mobile agent paradigm. We show that while existing protocols for fair exchange can be substantially simplified in the context of mobile agents, there are still many problems related to security which remain difficult to solve. We propose three increasingly flexible solutions to the fair exchange problem and show how to implement them using existing agent technology. The basis for ensuring the security properties of fair exchange is a tamper-proof hardware device called a trusted processing environment.