Obfuscating Quantum Hybrid-Classical Algorithms for Security and Privacy

Abstract

As quantum computing gains popularity, it’s crucial to tackle security and privacy issues upfront. One major concern is the involvement of third-party tools and hardware. With more quantum computing services available, even from less reputable sources, users might be drawn in by lower costs and easier access. However, usage of untrusted hardware could present the risk of intellectual property (IP) theft. For instance, popular algorithms like Quantum Approximate Optimization Algorithm (QAOA) encode graph properties in parameterized quantum circuits, opening the door to potential risks. For mission critical applications like power grid optimization, the graph structure can reveal the power grid and their connectivity (an IP that should be protected). To mitigate this risk, we propose an edge pruning obfuscation method for QAOA along with a split iteration methodology. The basic idea is to, (i) create two flavors of QAOA circuit each with few distinct edges eliminated from the problem graph for obfuscation, (ii) iterate the circuits alternately during optimization process to uphold the optimization quality, and (iii) send the circuits to two different untrusted hardware provider so that the adversary has access to partial graph protecting the IP. We demonstrate that combining edge pruning obfuscation with split iteration on two different hardware secures the IP and increases the difficulty of reconstruction while limiting performance degradation to a maximum of 10% ($\approx 5$% on average) and maintaining low overhead costs (less than 0.5X for QAOA with single layer implementation).