Secure assisted quantum computation

Suppose Alice wants to perform some computation that could be done quickly on a quantum computer, but she cannot do universal quantum computation. Bob can do universal quantum computation and claims he is willing to help, but Alice wants to be sure that Bob cannot learn her input, the result of her calculation, or even the function she is trying to compute. We describe an efficient protocol by which Bob can help Alice perform the computation, but there is no way for him to learn anything about it. Furthermore, we show how Alice can efficiently detect whether Bob is honestly helping her or if he is introducing errors.