A Unified Quantum Circuit Framework for Grover Search and Quantum Walks in NISQ Cryptanalysis
Published in ISCAS 2026, Shanghai, China, 2026
Recommended citation: L. Lavagna, G. Vittori, A. Rosato and M. Panella, "A Unified Quantum Circuit Framework for Grover Search and Quantum Walks in NISQ Cryptanalysis," 2026 IEEE International Symposium on Circuits and Systems (ISCAS), Shanghai, China, 2026, pp. 837-841 [https://ieeexplore.ieee.org/document/11562366](https://ieeexplore.ieee.org/document/11562366)
This paper explores the use of quantum search in symmetric cryptanalysis within the Noisy Intermediate-Scale Quantum (NISQ) regime, introducing a unified quantum circuit framework that expresses Grover’s algorithm as a coined quantum walk. This enables a direct comparison of the two approaches, previously treated separately, under a common model of circuital resources and noise. The framework is implemented and tested on cyclic permutations and AES-like primitives. Experiments show that, in the ideal case, the walk exhibits the familiar Grover amplification curve although, under realistic depolarizing and readout noise, the peaks are damped and the optimal number of steps falls below the theoretical value. In the AES examples, the probability of recovering the key remains negligible. Taken together, these results extend earlier analyses and suggest that symmetric encryption maintains classical-level security in the NISQ era of quantum circuits, while also providing a reproducible testbed for future studies.