Trading-off security and performance in barrier slicing for remote software entrusting

Network applications often require that a trust relationship is established between a trusted host (e.g., the server) and an untrusted host (e.g., the client). The remote entrusting problem is the problem of ensuring the trusted host that whenever a request from an untrusted host is served, the requester is in a genuine state, unaffected by malicious modifications or attacks. Barrier slicing helps solve the remote entrusting problem. The computation of the sensitive client state is sliced and moved to the server, where it is not possible to tamper with it. However, this solution might involve unacceptable computation and communication costs for the server, especially when the slice to be moved is large. In this paper, we investigate the trade-off between security loss and performance overhead associated with moving only a portion of the barrier slice to the server and we show that this trade-off can be reduced to a multi-objective optimization problem. We describe how to make decisions in practice with reference to a case study, for which we show how to choose among the alternative options.