Conditional payments for computing markets

Abstract

The problem of outsourcing computations in distributed environments has several security challenges. These challenges stem from the lack of trust between the outsourcer and a worker. Previous work has extensively considered one side of the trust problem - the efficient verification of the completion of the outsourced computation. We believe this to be the first work that simultaneously addresses the other side of trust - ensuring valid remuneration for the work. We propose a solution in which the outsourcer embeds a verifiable payment token into the computation to be performed. With high probability, the worker can verify that if it completes the computation it will retrieve the payment, and the outsourcer is convinced that if the worker retrieves the payment then it has completed the computation. We also discuss the robustness of our scheme against two possible attacks that target the desired security properties, and possible extensions to our scheme. © 2008 Springer Berlin Heidelberg.