QUANTUM-ENHANCED SYMMETRICAL CRYPTOANALYSIS OF S-AES

Objective of the study: to study the possibility of reducing quantum resource requirements for Grover's algorithm attack on block ciphers. Simplified-AES is considered as an example. To investigate the possibilities of using a partial key leakage. To estimate the required resources and to simulate a quantum attack on S-AES with reduced requirements. Research methods: algebraic analysis, numerical simulation. Research results: we have demonstrated the possibility of significantly reducing the number of qubits required to attack Simplified-AES by optimizing Grover's oracle. The resource requirements are reduced sufficiently, allowing to study quantum attack on Simplified-AES using numerical simulation on a PC with 400 MB of RAM in about 30 minutes (depending on the CPU configuration). A numerical simulation of a quantum attack on S-AES has been carried out for the case of an ideal leakage configuration, taking into account the elementary quantum noises. Scientific novelty: a new quantum attack algorithm for Simplified-AES cipher with significantly reduced requirements for the qubits number is proposed. Numerical simulation of the attack using this algorithm is carried out, which was practically impossible for previously known approaches. The results illustrate that our ideas about the resource requirements for a quantum attack and, as a consequence, the possible time of its practical implementation can be significantly incorrect if an alternative method for implementing even an already known asymptotically unimprovable quantum attack algorithm is found.