Quantum linear cryptanalysis on a toy cipher

A quantum version of the linear cryptanalysis technique is presented in this paper. So far, only a certain part of some classical cryptanalysis techniques was converted for quantum processing to gain speed-up while analysing a symmetric primitive. However, none of the quantum version of these attacks, including linear cryptanalysis, completely uses quantum computing for all the steps. We developed a quantum version for all the steps of the linear cryptanalysis. The proposed quantum linear cryptanalysis is applied on the quantum version of a toy cipher. Performance analysis shows that the quantum version of the linear cryptanalysis offers quadratic speed-up in different steps of the attack. It can be used to attack any cipher that is vulnerable against linear cryptanalysis.