  Offloading of computation, e.g., to the cloud, is today a major task in
distributed systems. Usually, consumers which apply offloading have to trust
that a particular functionality offered by a service provider is delivering
correct results. While redundancy (i.e., offloading a task to more than one
service provider) or (partial) reprocessing help to identify correct results,
they also lead to significantly higher cost.
  Hence, within this paper, we present an approach to verify the results of
offchain computations via the blockchain. For this, we apply zero-knowledge
proofs to provide evidence that results are correct. Using our approach, it is
possible to establish trust between a service consumer and arbitrary service
providers. We evaluate our approach using a very well-known example task, i.e.,
the Traveling Salesman Problem.
