Quantum implementation of SLIM and its Grover cryptanalysis
H O Cildiroglu, Oğuz Yayla · Physica Scripta · 2025
Abstract We present a novel quantum implementation of SLIM, a lightweight 32/80-bit Feistel cipher. By inverting its Key addition-Substitution-Permutation (KSP) layers without ancillary qubits, we construct the full quantum circuit using 112 qubits with quantum cost 30,404 and depth 4,066. To assess quantum resilience, we implement Grover’s algorithm with three plaintext-ciphertext pairs (r = 3; 337 qubits), yielding an attack cost of 2 111 under NIST’s MAXDEPTH constraints—below the Level-1 threshold 2 170 . While SLIM falls short of NIST’s security threshold for near-term quantum attacks, among other lightweight BCs, its efficient architecture retains practical advantages for constrained applications.