Impact of the malicious input data modification on the efficiency of quantum spatial search

In this paper, we demonstrate that the efficiency of quantum spatial search can be significantly altered by malicious manipulation of the input data in the client–server model. We achieve this by exploiting exceptional configuration effect on Szegedy spatial search and proposing a framework suitable for analysing efficiency of attacks on quantum search algorithms. We provide the analysis of proposed attacks for different models of random graphs. The obtained results demonstrate that quantum algorithms in general are not secure against input data alteration.