If large-scale quantum computers capable of running quantum algorithms are developed, it is expected that powerful quantum cryptanalysis will become possible. To establish secure quantum-resistant encryption systems, it is necessary to evaluate the quantum security of cryptographic algorithms. As a result, various quantum cryptanalysis research studies have been published, and implementation techniques that minimize the resources required for analyzing encryption have been proposed. In this paper, we present an efficient quantum circuit implementation of Classic McEliece, which is one of the candidate algorithms in the NIST Post-Quantum Cryptography Standardization Round 4. We optimize the encoding, and decoding operations of Classic McEliece on quantum circuits, with a specific focus on binary field arithmetic, linear operations, and the Berlekamp-Massey decoding quantum circuit.
If large-scale quantum computers capable of running quantum algorithms are developed, it is expected that powerful quantum cryptanalysis will become possible. To establish secure quantum-resistant encryption systems, it is necessary to evaluate the quantum security of cryptographic algorithms. As a result, various quantum cryptanalysis research studies have been published, and implementation techniques that minimize the resources required for analyzing encryption have been proposed. In this paper, we present an efficient quantum circuit implementation of Classic McEliece, which is one of the candidate algorithms in the NIST Post-Quantum Cryptography Standardization Round 4. We optimize the encoding, and decoding operations of Classic McEliece on quantum circuits, with a specific focus on binary field arithmetic, linear operations, and the Berlekamp-Massey decoding quantum circuit.
Code-based cryptosystems are a promising option for Post-Quantum Cryptography, as neither classical nor quantum algorithms provide polynomial time solvers for their underlying hard problem. Indeed, to provide sound alternatives to lattice-based cryptosystems, U.S. National Institute of Standards and Technology (NIST) advanced all round 3 code-based cryptosystems to round 4 of its Post-Quantum standardization initiative. We present a complete implementation of a quantum circuit based on the Information Set Decoding (ISD) strategy, the best known one against code-based cryptosystems, providing quantitative measures for the security margin achieved with respect to the quantum-accelerated key recovery on AES, targeting both the current state-of-the-art approach and the NIST estimates. Our work improves the state-of-the-art, reducing the circuit depth by 2 19 to 2 30 for all the parameters of the NIST selected cryptosystems, mainly due to an improved quantum Gauss–Jordan elimination circuit with respect to previous proposals. We show how our Prange’s-based quantum ISD circuit reduces the security margin with respect to its classical counterpart. Finally, we address the concern brought forward in the latest NIST report on the parameters choice for the McEliece cryptosystem, showing that its parameter choice yields a computational effort slightly below the required target level.
Quantum computers have shown their capability to outperform the world's fastest supercomputers despite their nascent stage. This poses questions about the security of existing encryption schemes and offers exciting new possibilities to the field of cryptography. Extension of existing cryptographic algorithms and development of novel cryptographic protocols exploiting the physics of the quantum realm are unique prospects for the industry moving forward. This work implemented a hybrid classical-quantum AES-128 circuit on the open-source Qiskit simulator and explored the possibilities of reducing the qubit count necessary for implementing the same. Multiple classical bits were encoded into a single qubit for processing, and a machine learning model was trained to decode the output data back to classical bits. The circuit size was halved by changing the encoding form of classical bits into qubits. Our hybrid circuit also achieved significant speed up over the existing hybrid circuit for AES encryption and decryption.
Providing strong security margins against cryptanalytic attackers equipped with quantum computers is a major research direction fostered by the US National Institute of Standards and Technology (NIST) Post-quantum Cryptography Standardization process. Among the viable candidates, code-based asymmetric cryptosystems are one of the prominent approaches. In this work, we propose the first fully detailed quantum circuit to compute the solution to the Information Set Decoding problem, the main cryptanalytic tool against such cryptosystems. We evaluate the cryptanalytic effort with our circuit design on actual parameters from cryptosystems admitted to the final stage of the NIST standardization process and compare it with the previous conservative asymptotic estimates. We show that the actual computational effort of our solution is smaller than the one estimated via asymptotics by a factor of 24. We also perform a comparison of our results with the quantum-computational effort of breaking the AES cipher, following the guidelines of the US NIST in evaluating the security of the ciphers. To do this, we translate our design on gates of the Clifford+T gate set only, one of the most promising candidate for fault-tolerant quantum computation, and report that the parameter choices for Classic McEliece and BIKE, two candidates admitted to the final round of the NIST standardization process provide an adequate security margin with respect to our ISD solution technique.
Quantum search algorithms, such as Grover's algorithm, will soon pose a threat to current encryption standards as quantum computing advances toward practical implementation. These algorithms rely on quantum circuits that map cryptographic algorithms into appropriate Hilbert spaces, thus linking algorithmic inputs and outputs through quantum superposition. However, implementing and testing such circuits on existing quantum simulators, such as Qiskit, encounters significant memory and computational bottlenecks that limit research progress. To address these simulation constraints, we present a resource-optimized quantum circuit implementation of a complete two-round Mini-AES encryption algorithm. Our approach systematically converts the cipher's algebraic structure using algebraic normal form (ANF) equations, mapping XOR operations to CNOT gates and AND operations to Toffoli gates. To reduce memory overhead, we implement an ancilla-reuse strategy utilizing mid-circuit measurements and resets. Additionally, we introduce an automated procedure that generates Qiskitcompatible quantum circuits for arbitrary S-boxes and cryptographic primitives, streamlining the development of quantum cryptanalysis implementations. Our implementation achieves full encryption and decryption in a quantum circuit with modest gate requirements that can be achieved by the current or near-future state of the art quantum computers. In addition, we provide system utilization metrics to validate our resource-constrained implementation. This compact and pedagogically accessible implementation establishes a practical foundation for quantum cryptanalysis research and post-quantum cryptographic analysis.
The advance of quantum computing poses significant risks to traditional cryptographic systems, including RSA and ECC, due to algorithms such as Shor's, prompting an urgent need for robust post-quantum cryptography (PQC) solutions. This paper presents a systematic review of PQC algorithms, encompassing lattice-based, code-based, multivariate polynomial, hash-based, and supersingular isogeny-based cryptography. By evaluating recent publications and NIST standardization efforts, we assess these approaches in terms of quantum resistance, computational efficiency, scalability, and implementation challenges. Lattice-based schemes, notably CRYSTALS-Kyber, excel in quantum-secure encryption and performance, whereas codebased systems like McEliece are hindered by large key sizes. Hash-based signatures, such as SPHINCS+, and isogeny-based protocols, including SIDH, provide promising alternatives but require further optimization to reduce computational overhead. Our analysis highlights the potential of hybrid PQC methods and lightweight hardware implementations for securing emerging domains like IoT, blockchain, and financial systems. The review serves as a foundational resource for researchers and practitioners, advocating the adoption of quantum-resistant cryptography to preserve data confidentiality, integrity, and authenticity in the quantum era.
Quantum computing has advanced rapidly in recent decades, driven by developments across the technology stack, including quantum error-correcting codes and efficient quantum algorithms. Among these, quantum arithmetic circuits serve as fundamental building blocks for various promising algorithms. Despite their crucial role, the design of quantum arithmetic circuits faces challenges arising from the no-cloning theorem, qubit limitations, and circuit depth constraints, which significantly impact the efficiency of large-scale quantum computing. We provide an overview of quantum arithmetic circuits in the context of public-key cryptanalysis, with particular emphasis on optimization strategies such as measurement-based uncomputation and conditionally clean ancilla. We review state-of-the-art designs for essential arithmetic operations in public-key cryptanalysis such as addition, multiplication, and modular exponentiation. We also present an overview of the techniques used for fault-tolerant runtime and resource estimation in quantum cryptanalysis. In brief, this chapter emphasizes strategies for designing resource-efficient quantum arithmetic circuits, providing a basis for realistic evaluations of quantum cryptanalytic capabilities.