In this chapter, we show how to guarantee correctness when applying multiparty computation in outsourcing scenarios. Specifically, we consider how to guarantee the correctness of the result when neither the parties supplying the input nor the parties performing the computation can be trusted. Generic techniques to achieve this are too slow to be of practical use. However, we show that it is possible to achieve practical performance for specific problems by exploiting the existence of certificates proving that a computation result is correct.