Tweakable block ciphers are more flexible than traditional block ciphers and widely used in modes of operation such as MAC and authenticated encryption. With the development of quantum computing, the threat of quantum algorithms to the security of cryptosystems is increasing. Research shows that some classical secure symmetric cryptographic constructions or schemes become vulnerable to the quantum attacks based on Simon's algorithm. This paper studies the security of tweakable block cipher constructions under quantum attacks based on Simon's algorithm, summarizes the quantum attack methods of Simon's algorithm and quantum-resistant constructions, and provides methods to enhance the quantum security of tweakable block ciphers.
Tweakable block ciphers are more flexible than traditional block ciphers and widely used in modes of operation such as MAC and authenticated encryption. With the development of quantum computing, the threat of quantum algorithms to the security of cryptosystems is increasing. Research shows that some classical secure symmetric cryptographic constructions or schemes become vulnerable to the quantum attacks based on Simon's algorithm. This paper studies the security of tweakable block cipher constructions under quantum attacks based on Simon's algorithm, summarizes the quantum attack methods of Simon's algorithm and quantum-resistant constructions, and provides methods to enhance the quantum security of tweakable block ciphers.
Recent results on quantum cryptanalysis show that some symmetric key schemes can be broken in polynomial time even if they are proven to be secure in the classical setting. Liskov, Rivest, and Wagner showed that secure tweakable block ciphers can be constructed from secure block ciphers in the classical setting. However, Kaplan et al. showed that their scheme can be broken by polynomial time quantum superposition attacks, even if underlying block ciphers are quantum-secure. Since then, it remains open if there exists a mode of block ciphers to build quantum-secure tweakable block ciphers. This paper settles the problem in the reduction-based provable security paradigm. We show the first design of quantum-secure tweakable block ciphers based on quantum-secure block ciphers, and present a provable security bound. Our construction is simple, and when instantiated with a quantum-secure n-bit block cipher, it is secure against attacks that query arbitrary quantum superpositions of plaintexts and tweaks up to O(2n/6) quantum queries. Our security proofs use the compressed oracle technique introduced by Zhandry. More precisely, we use an alternative formalization of the technique introduced by Hosoyamada and Iwata.
Block ciphers are versatile cryptographic ingredients that are used in a wide range of applications ranging from secure Internet communications to disk encryption. While post-quantum security of public-key cryptography has received significant attention, the case of symmetric-key cryptography (and block ciphers in particular) remains a largely unexplored topic. In this work, we set the foundations for a theory of post-quantum security for block ciphers and associated constructions. Leveraging our new techniques, we provide the first post-quantum security proofs for the key-length extension scheme FX, the tweakable block ciphers LRW and XEX, and most block cipher encryption and authentication modes. Our techniques can be used for security proofs in both the plain model and the quantum ideal cipher model. Our work takes significant initial steps in establishing a rigorous understanding of the post-quantum security of practical symmetric-key cryptography.
With the development of quantum technology, quantum computing has an increasingly significant impact on cryptanalysis. Several quantum algorithms, such as Simon’s algorithm, Grover’s algorithm, the Bernstein–Vazirani algorithm, Shor’s algorithm, and the Grover-meets-Simon algorithm, have been proposed successively. However, almost all cryptanalysis is based on the quantum chosen-plaintext attack (qCPA) model. This paper focuses on a powerful cryptanalytic model, quantum related-key attack (qRKA), and proposes a strategy of qRKAs against symmetric ciphers using Simon’s algorithm. We construct a periodic function to efficiently recover the secret key of symmetric ciphers if the attacked symmetric ciphers satisfy Simon’s promise, and present the complexity analysis on specific symmetric ciphers. Then, we apply qRKA to the Even–Mansour cipher and SoEM construction, recover their secret keys, and show their complexity comparison in the distinct attack models. This work is of great significance for the qRKA cryptanalysis of existing provably secure cryptographic schemes and the design of future quantum secure cryptographic schemes.
Recent advances in cryptography aim to address threats posed by quantum computers. However, these advances have focused disproportionately on asymmetric schemes, while symmetric primitives like block ciphers have received less attention. The common assumption is that doubling block cipher key sizes provides adequate quantum resistance, but this oversimplifies the challenge. This paper provides a systematic examination of block cipher security in the quantum computing era. The paper first establishes a formal framework for understanding block cipher security, covering their mathematical foundations and essential security properties. Building on this foundation, we examine how quantum computing fundamentally challenges these security assumptions, going beyond the simple impact on key lengths. Our review of recent research reveals that quantum attacks can exploit structural vulnerabilities in block ciphers and their modes of operation, requiring more comprehensive defenses than key length adjustments alone. We analyze emerging approaches in quantum-resistant design and identify critical areas requiring further research to ensure block cipher security in a post-quantum world.
Cryptography has long been an essential tool in safeguarding digital communication and securing sensitive information. As technology has progressed, so has the complexity of the methods used to protect our data. In the wake of quantum computing's rise, traditional cryptographic systems face serious challenges, demanding a new understanding of how quantum algorithms could both undermine and enhance security. Chapter 1 deals with the Basics of Cryptography lays the groundwork by introducing classical cryptography, tracing its evolution from ancient ciphers to modern cryptosystems. In Chapter 2, readers are introduced to Quantum Algorithms, the principles of quantum mechanics relevant to computing, including qubits, superposition, and entanglement. The Chapter 3 focuses on Shor’s algorithm, a landmark quantum algorithm that threatens the security of widely used public-key cryptosystems like RSA and ECC. In Chapter 4 Grover’s Algorithm is examined in the context of brute-force attacks on symmetric key cryptography. Chapter 5 focusing on Simon’s Algorithm and its role in breaking cryptographic primitives through structure exploitation. In Chapter 6 a broader discussion about Cryptographic Implications of Quantum Computing is given on how quantum computing affects modern cryptographic systems. Finally, in Chapter 7, the future of cryptography in the quantum era is discussed.
Cryptography, the practice of concealing messages for private exchange, has evolved significantly to address the challenges posed by new communication methods. In today`s digital world, cryptography has become the cornerstone of cybersecurity, using advanced mathematics like number theory and computational complexity to protect digital information through algorithms. The upcoming arrival of quantum computers poses a serious threat to traditional cryptographic methods, especially those based on asymmetric key cryptography. Quantum Safe Cryptography (QSC) represents the next step in information security, designed to develop cryptographic systems that can withstand attacks from both quantum and classical computers. As quantum computing moves from theory to reality, it`s becoming clear that current cryptographic methods based on integer factorization and discrete logarithm problems are vulnerable to quantum algorithms like Shor`s algorithm. This study highlights the security risks that quantum computing poses to existing encryption methods and proposes a comprehensive approach to quantum-safe cryptography. The transition to quantum-resistant algorithms involves replacing vulnerable cryptographic systems with alternatives that can resist quantum computational attacks. Current analysis shows that while asymmetric key cryptography faces immediate vulnerability, symmetric key algorithms and hash functions remain relatively secure in the near term with appropriate adjustments. Quantum cryptography, which directly uses quantum mechanical principles, offers highly secure encryption mechanisms, notably Quantum Key Distribution (QKD). This research aims to enhance the security of digital infrastructure against quantum threats by evaluating hybrid cryptographic implementations that combine classical and quantum-resistant approaches for optimal security.