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arXiv:2605.25728

Q-LEAK: Quantum-Based LEAKage Verification for Side-Channel Countermeasures

Walid El Maouaki, Alberto Marchisio, Muhammad Shafique

On Aqora:Muhammad ShafiqueMuhammad Shafique
quant-phSubmitted May 25, 2026• Announced May 26, 2026• 0 citations
v1 · May 25, 2026v2 · Oct 3, 2026
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Abstract

Formal verification of power side-channel leakage and its countermeasures in cryptographic algorithms is challenging, as SAT-based methods fail to scale on XOR-heavy, time-unrolled cryptographic circuits with realistic leakage models. We construct compact Conjunctive Normal Form (CNF) cases modeling one-bit leakage under two-trace conditions, linking key dependence and state evolution. Classical solvers quickly reach complexity limits, so we propose Q-LEAK, a quantum-based verification approach using Grover's algorithm, compiling each CNF into an oracle and applying amplitude amplification to search in O(sqrt(N)) oracle calls, with oracles that encode the two-trace leakage predicate and the CNF constraints. Benchmarking against classical SAT shows both potential gains and practical resource limits. In noiseless tests on 5-7 variable benchmarks, Q-LEAK consistently recovered a satisfying assignment within 1-4 tries, with marked bitstrings amplified clearly above the background distribution, exceeding 20 percent probability. The evaluation of Q-LEAK on real quantum hardware revealed at least one classically verified SAT assignment, despite the presence of noise. These results point to a potential path toward quantum-assisted verification of side-channel protections.

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Formal verification of power side-channel leakage and its countermeasures in cryptographic algorithms is challenging, as SAT-based methods fail to scale on XOR-heavy, time-unrolled cryptographic circuits with realistic leakage models. We construct compact Conjunctive Normal Form (CNF) cases modeling one-bit leakage under two-trace conditions, linking key dependence and state evolution. Classical solvers quickly reach complexity limits, so we propose Q-LEAK, a quantum-based verification approach using Grover's algorithm, compiling each CNF into an oracle and applying amplitude amplification to search in O(sqrt(N)) oracle calls, with oracles that encode the two-trace leakage predicate and the CNF constraints. Benchmarking against classical SAT shows both potential gains and practical resource limits. In noiseless tests on 5-7 variable benchmarks, Q-LEAK consistently recovered a satisfying assignment within 1-4 tries, with marked bitstrings amplified clearly above the background distribution, exceeding 20 percent probability. The evaluation of Q-LEAK on real quantum hardware revealed at least one classically verified SAT assignment, despite the presence of noise. These results point to a potential path toward quantum-assisted verification of side-channel protections.
The use of Boolean Satisfiability (SAT) solver for hardware verification incurs exponential runtime in several instances. In this work, we have proposed an efficient quantum SAT (qSAT) solver for equivalence checking of Boolean circuits employing Grover’s algorithm. The Exclusive-Sum-of-Product (ESOP)-based generation of the Conjunctive Normal Form (CNF) equivalent clauses demands less qubits and minimizes the gates and depth of quantum circuit interpretation. The consideration of reference circuits for verification affecting Grover’s iterations and quantum resources are also presented as a case study. Experimental results are presented assessing the benefits of the proposed verification approach using open source Qiskit platform and IBM quantum computer.
Physical implementations of cryptographic algorithms leak information, which makes them vulnerable to so-called side-channel attacks.Cryptography is now used in an ever-increasing variety of scenarios, and the assumption that the execution of cryptosystems is physically insulated is often not realistic.The field of leakage resilience proposes to mitigate side-channel attacks by designing protocols that are secure even if information leaks during execution.In this work, we study leakage-resilient computation, which concerns the problem of performing secure universal computation in the presence of leakage.Fault-tolerant quantum computation is concerned with the problem of noise in quantum computers.Since it is very hard to insulate quantum systems from noise, fault tolerance proposes schemes for performing computations correctly even if some noise is present.It turns out that there exists a connection between leakage resilience and fault tolerance.In this work, we show that leakage in a classical circuit is a form of noise, when the circuit is interpreted as quantum.We then prove that for an arbitrary leakage model, there exists a corresponding noise model in which a circuit that is fault-tolerant against the noise model is also resilient against the given leakage model.We also show how to use constructions for fault tolerance to implement classical circuits that are secure in specific leakage models.This is done by establishing criteria in which quantum circuits can be converted into classical circuits in such a way that the leakage resilience property is preserved.Using these criteria, we convert an implementation of universal fault-tolerant quantum computation into a classical leakageresilient compiler, i.e., a scheme that compiles an arbitrary circuit into a circuit of the same functionality that is leakage-resilient.vi 4.9 (a): Circuito de codificação para |0 no código de Steane.O circuito que codifica |+ é o mesmo, com a diferença de que alvos e controles são revertidos, e estados |0 são revertidos em |+ e vice-versa.(b):
Satisfiability (SAT) is a central problem in computer science, and advances in SAT-solving algorithms have a far-reaching impact across many fields. Recent works have proposed quantum SAT solvers based on Grover's algorithm, a quantum search technique. However, Grover-based approaches face a key limitation: they typically require prior knowledge of the number of satisfying assignments of the target Boolean formula. This information is unavailable in most practical settings. Quantum counting can be used to estimate this quantity, but it incurs a computational overhead that is several orders of magnitude higher than Grover search. In this paper, we propose a novel quantum SAT solver based on entanglement and equivalence checking. Our method does not assume prior knowledge of the number of solutions and is computationally more efficient than quantum counting. Although the worst case time complexity is inevitably exponential, we prove that the expected time complexity of our approach is only constant time O(1) over random Boolean functions. Experimental results also support our theoretical claim.
Side-channel attacks on block ciphers rarely recover the key outright: they leave a residual key space ordered by subkey posteriors, and evaluation laboratories report the key rank of the true key against thresholds near 2^48 and 2^60. No evaluation framework models an adversary who collects traces classically and finishes the search on a quantum computer, although quantum search with advice provides exactly that. We give such an adversary a cost model and a metric. For a device whose key has rank r, any quantum algorithm with classical access to the posteriors needs Omega(sqrt(r)) cipher evaluations, and block search achieves O(sqrt(r)); the per-instance advantage is exactly quadratic, and the super-quadratic exponents reported for search with advice are averages over the prior that apply to no single device. Under the NIST MAXDEPTH budget D and a Grover iteration of g gates and depth d, the quadratic advantage holds only for ranks up to (4D/(pi d))^2 and collapses to a constant factor beyond; with the best published AES-128 oracle and D = 2^40 the window closes near rank 2^58.6. We define the quantum-aware key rank, the classical rank of equal cost, computable from the rank estimators laboratories already run, and derive the classical rank a device must retain to keep a given threshold against each depth budget. Block search and amplitude amplification from the product-form posterior state are within a factor of two to four of each other on Hamming-weight posteriors, so the cost of coherent indexing decides between them. Experiments on simulated leakage and a toy cipher confirm the predicted window: at SNR 0.125 a depth-limited quantum adversary is worth about 22 traces to a classical one, however large its gate budget.
Post-quantum cryptography (PQC) is designed to be secure against attacks from quantum computers, yet it remains vulnerable to classic side-channel attacks (SCAs), which exploit physical implementation leaks. This manuscript examines the various SCAs used to evaluate PQC schemes, focusing on non-invasive techniques such as timing, power, and electromagnetic analysis. We provide a detailed account of the execution of these attacks against diverse PQC algorithms and identify common vulnerabilities and weaknesses. Our study reveals that, while various countermeasures have been proposed to protect PQC implementations, they are not entirely effective against sophisticated attacks. Stronger and more resilient countermeasures are needed, especially in IoT environments. The review highlights the weaknesses in the current defenses, including the necessity for more robust masking techniques, adequate security countermeasures tailored to IoT constraints, and methods to generalize SCAs across diverse hardware platforms. These issues must be addressed to enhance the practical security of PQC schemes in real-world scenarios.
The K-SAT problem is a fundamental challenge in computational theory, widely used in artificial intelligence, cryptography, and optimization. Classical algorithms struggle with exponential time complexity, making them inefficient for large-scale instances. In this research, we propose an efficient quantum computing approach based on Grover’s algorithm to enhance the search process for satisfiable solutions in K-SAT problems. Our implementation leverages quantum superposition and amplitude amplification to explore multiple possible solutions simultaneously, reducing the search complexity from O (2ⁿ) in classical methods to O(√2ⁿ) in quantum computing. We design a quantum oracle that encodes the K-SAT clauses and integrates it into Grover’s iterative search framework. The performance is evaluated through Qiskit simulations, demonstrating a significant improvement in search efficiency compared to classical brute-force techniques. The results highlight the potential of quantum algorithms in solving complex combinatorial problems with enhanced speed and accuracy. This study contributes to the development of quantum-accelerated optimization methods, paving the way for real-world applications in machine learning, cryptanalysis, and large-scale data processing.