In peer-to-peer systems, nodes rely on other nodes to route and forward messages to their destinations. If peer-to-peer technology is to be used in a business context, intermediary nodes might have an incentive not to adhere to the specified routing protocol if there is a benefit to be gained from doing so. We address the problem of rationality and self-interest in this context by hiding the content and the originator of messages from intermediary peer nodes. Consequently, rational nodes cannot selectively discriminate against messages originating from particular senders or messages with a specific content. Our proposal is based on the concept of split knowledge, where a message is split into two parts at its origin and these parts are then routed to the destination via two disjoint paths. We present a method of how this concept can be implemented in the CHORD peer-to-peer system. We propose a simple modification to the CHORD routing protocol that allows finding multiple path between two CHORD nodes with a low degree of overlap. Simulation results and analytical approximations demonstrate the performance of the proposed method.