Motivated by Shor’s algorithm and its attractive features, the milestone results in quantum cryptanalysis were the discovery of quantum differential and linear cryptanalysis. In quantum cryptanalysis, quantum distinguishers imitate the classical setting. Details differ; however, as the distinguisher in the quantum setting can take maximum coset superposition of all possible subsets of plaintext pairs. Using quantum measurements, the winning gap of the game is exploited so that a distinguisher can still guess the secret key perfectly with a constant probability. Symmetric primitives also suffer reduced ideal security in the quantum world, but this security reduction is less drastic than for most asymmetric primitives. Stream ciphers, block ciphers, and cryptographic hash functions are primitives that are believed to resist quantum attacks. Analogs to Shor’s algorithm may say how hard it is to build a quantum computer, but devising quantum algorithms to outperform the best classical attacks for widely-used cryptographic primitives is probably outside the reach of current even if exponentially growing noisy intermediate-scale quantum (NISQ) computers.
Motivated by Shor’s algorithm and its attractive features, the milestone results in quantum cryptanalysis were the discovery of quantum differential and linear cryptanalysis. In quantum cryptanalysis, quantum distinguishers imitate the classical setting. Details differ; however, as the distinguisher in the quantum setting can take maximum coset superposition of all possible subsets of plaintext pairs. Using quantum measurements, the winning gap of the game is exploited so that a distinguisher can still guess the secret key perfectly with a constant probability. Symmetric primitives also suffer reduced ideal security in the quantum world, but this security reduction is less drastic than for most asymmetric primitives. Stream ciphers, block ciphers, and cryptographic hash functions are primitives that are believed to resist quantum attacks. Analogs to Shor’s algorithm may say how hard it is to build a quantum computer, but devising quantum algorithms to outperform the best classical attacks for widely-used cryptographic primitives is probably outside the reach of current even if exponentially growing noisy intermediate-scale quantum (NISQ) computers.
Quantum computers, that may become available one day, would impact many scientific fields, most notably cryptography since many asymmetric primitives are insecure against an adversary with quantum capabilities. Cryptographers are already anticipating this threat by proposing and studying a number of potentially quantum-safe alternatives for those primitives. On the other hand, symmetric primitives seem less vulnerable against quantum computing: the main known applicable result is Grover’s algorithm that gives a quadratic speed-up for exhaustive search. In this work, we examine more closely the security of symmetric ciphers against quantum attacks. Since our trust in symmetric ciphers relies mostly on their ability to resist cryptanalysis techniques, we investigate quantum cryptanalysis techniques. More specifically, we consider quantum versions of differential and linear cryptanalysis. We show that it is usually possible to use quantum computations to obtain a quadratic speed-up for these attack techniques, but the situation must be nuanced: we don’t get a quadratic speed-up for all variants of the attacks. This allows us to demonstrate the following non-intuitive result: the best attack in the classical world does not necessarily lead to the best quantum one. We give some examples of application on ciphers LAC and KLEIN. We also discuss the important difference between an adversary that can only perform quantum computations, and an adversary that can also make quantum queries to a keyed primitive.
Quantum computers, that may become available one day, would impact many scientific fields, most notably cryptography since many asymmetric primitives are insecure against an adversary with quantum capabilities. Cryptographers are already anticipating this threat by proposing and studying a number of potentially quantum-safe alternatives for those primitives. On the other hand, symmetric primitives seem less vulnerable against quantum computing: the main known applicable result is Grover's algorithm that gives a quadratic speed-up for exhaustive search. In this work, we examine more closely the security of symmetric ciphers against quantum attacks. Since our trust in symmetric ciphers relies mostly on their ability to resist cryptanalysis techniques, we investigate quantum cryptanalysis techniques. More specifically, we consider quantum versions of differential and linear cryptanalysis. We show that it is usually possible to use quantum computations to obtain a quadratic speed-up for these attack techniques, but the situation must be nuanced: we don't get a quadratic speed-up for all variants of the attacks. This allows us to demonstrate the following non-intuitive result: the best attack in the classical world does not necessarily lead to the best quantum one. We give some examples of application on ciphers LAC and KLEIN. We also discuss the important difference between an adversary that can only perform quantum computations, and an adversary that can also make quantum queries to a keyed primitive.
The advent of quantum computing presents a paradigm shift in the field of cryptanalysis, challenging the security of classical encryption schemes that underpin modern digital communications. This study explores the capabilities of quantum algorithms, particularly Shor's algorithm and Grover's algorithm, in undermining widely used cryptographic systems. Shor's algorithm poses a direct threat to publickey cryptosystems such as RSA and ECC by enabling efficient integer factorization and discrete logarithm computation, which are computationally infeasible for classical computers. Meanwhile, Grover's algorithm provides a quadratic speedup for bruteforce attacks on symmetric-key cryptosystems like AES, significantly reducing their effective security. Through theoretical analysis and simulation-based evaluation, this paper highlights the vulnerabilities of classical encryption in the face of quantum advances and underscores the urgent need for post-quantum cryptographic solutions. The findings emphasize the critical importance of transitioning to quantum-resistant algorithms to ensure long-term data confidentiality in a future dominated by quantum technologies.
The advent of quantum computing poses an existential threat to classical cryptographic systems. Shor’s algorithm (1994) can factor large integers and compute discrete logarithms in polynomial time, breaking widely used schemes like RSA, ECC, and Diffie-Hellman. This paper surveys the state-of-the-art in quantum cryptanalysis, examining its impact on symmetric and asymmetric cryptography, recent progress in quantum attacks, and defenses via post-quantum cryptography (PQC). We analyze key quantum algorithms (Shor’s, Grover’s), their real-world feasibility given current hardware (NISQ-era limitations), and emerging PQC standards (NIST’s CRYSTALS-Kyber, Dilithium). We also discuss novel attack vectors (e.g., hybrid quantum-classical cryptanalysis) and future research directions.
This paper investigates the potential impact of quantum computing on the security of currently deployed cryptographic algorithms. The core premise is that the advent of powerful quantum computers, leveraging algorithms like Shor's algorithm and Grover's algorithm, poses a significant threat to widely used public-key cryptosystems and symmetric-key algorithms. We present a theoretical analysis of several key algorithms – RSA, ECC, and AES – examining their vulnerabilities when subjected to quantum attacks. Specifically, we explore the exponential speedup offered by Shor's algorithm for factoring large numbers, the impact on the key size of ECC, and the Grover's algorithm's influence on symmetric key search. Our work highlights the urgency of transitioning to post-quantum cryptography standards to mitigate the risks posed by this technological advancement. The goal is to provide a comprehensive understanding of the landscape of quantum cryptanalysis and its implications for the future of secure communication.
Quantum computing poses a fundamental threat to modern cryptographic protocols by exploiting quantum algorithms that surpass classical computational limits. Shor’s algorithm can efficiently factor large integers, breaking RSA and other public-key cryptosystems, while Grover’s algorithm accelerates brute-force attacks against symmetric encryption. As quantum hardware advances, traditional cryptographic schemes risk obsolescence, necessitating the development of quantum-resistant cryptographic techniques. This paper explores the theoretical foundations of quantum cryptanalysis, examining key algorithms, their implications for cybersecurity, and the current state of post-quantum cryptographic solutions. By analyzing resource estimates for quantum attacks and potential mitigation strategies, this study provides a comprehensive overview of the evolving cryptographic landscape in the quantum era.