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.
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.
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.
In today’s world more and more electronic devices are connected through the channel “internet”. To secure these devices, designers rely on cryptographic standards that provide encryption, authentication and data-integrity. However, future advances in quantum computing threaten the security of these standards as they are predicted to break the underlying hard mathematical problems. It is therefore of the utmost importance to find new standards that are safe against quantum computers. The design and analysis of such quantum-safe algorithms is studied in the field of many post-quantum encryption schemes are subject to decryption failures. This means that even after a proper execution of the algorithm, there is a (very small) chance that the message or key is not transmitted correctly. It simply led like that decryption failures lead to a new attack vector in which failing cipher texts are assembled and used to reconstruct the secret key. To secure the connected devices and data the method of Post Quantum Cryptography will plays a vital role. Post Quantum Cryptography improves the security proof bound on decryption failure attacks.
The development of quantum computers represents an important advancement in computing, using quantum mechanics to address problems that were previously difficult to solve. This technological advancement poses a challenge for cryptographic systems. While some methods are known to be vulnerable, the impact of quantum computing on symmetric cryptography has received less research attention, largely because the common advice is to simply double the key size. This paper explores how quantum computing affects symmetric cryptography, focusing on block cipher-based cryptography. It surveys existing literature on the quantum resilience of symmetric cryptographic primitives based on block ciphers and their security in various scenarios. Not all symmetric cryptographic functionalities are quantum-secure, and their security depends on the specific adversary model being considered. We provide an overview of the research conducted and pinpoint areas where further investigation is needed.
Recent developments in quantum computers pose an imminent threat to cryptography since many widely used cryptographic schemes will no longer be secure. This worrisome scenario motivated a growing interest in the field of post-quantum cryptography, which aims to design cryptosystems that are postquantum secure, i.e. secure against quantum-capable adversaries. While finding post-quantum computational hardness assumptions is pivotal to achieve this goal, an issue that is often overlooked is provable security. In fact, to prove that the post-quantum computational hardness necessarily implies post-quantum security of the derived cryptosystem, the reduction argument that establishes this implication also needs to be post-quantum. As such, many new methods have been devised in the last few years to handle this adaptation to the quantum setting. In particular, the quantum analogue of the Random Oracle Model has garnered special interest, as it is the foundation of many cryptographic schemes, from public-key encryption to digital signatures. It is also very problematic and usually the main culprit of the failure of security proofs when transitioning to the quantum setting. This work offers a comprehensive exposition on the most influential techniques developed in the last decade to enable or facilitate the construction of security proofs in the Quantum Random Oracle Model (QROM). Each presented technique offers an unique purpose and a solution to a problem provoked by the QROM, and, as such, as a whole, this works allows for an understanding of the most common strategies to construct these type of security proofs. This is accomplished by presenting and analyzing the security proof of three cryptographic schemes set in this model, which underlines the central role these techniques take in provable quantum security.
Abstract It is viewed as revolutionary technology, offering incredible potential in terms of computing power within different scientific and industrial sectors. Quantum computers provide remarkable computing power; however, they also present significant security risks to existing public-key cryptography systems used to secure digital communication, online banking systems, government, medical applications, cloud computing systems, and IoT systems. Security of commonly used encryption schemes like RSA, DH, and ECC depends on mathematical problems that are impossible for classical computers to solve but can be easily resolved with the help of powerful enough quantum computers by using Shor’s algorithm. Furthermore, Grover’s algorithm makes exhaustive search attacks much faster, thus effectively lowering the security level of symmetric encryption schemes since it provides the speed-up for brute-force attacks. Post-Quantum Cryptography (PQC) turned out to be an effective and scalable method to protect digital data from attacks using quantum computing. In contrast to quantum cryptography, which requires a special quantum communication channel, PQC uses classical cryptographic algorithms that cannot be broken down by either classical or quantum computer due to certain mathematical problems. This research paper offers an extensive exploration of post-quantum cryptography through the analysis of the development of quantum computing, weaknesses of current cryptographic techniques, and mathematics behind quantum-resistant algorithms. Moreover, this paper explores the major classes of PQC techniques such as lattice-based, code-based, hash-based, multivariate, and isogeny-based cryptography and provides details about their security and application. Moreover, the report gives an overview of the NIST Post-Quantum Cryptography Standardization Project and analyzes recent standardizations of quantum-proof algorithms to be utilized in future digital infrastructures. Keywords: Post-Quantum Encryption, Quantum Security, Quantum-Proof Public-Key Cryptography, Lattice-Based Security Protocols, ML-KEM Key Encapsulation Mechanism, ML-DSA Digital Signature Algorithm, NIST Post-Quantum Cryptography, Contemporary Cybersecurity, Secure Communications, Cryptographic Algorithms.
Cryptography has evolved from ancient substitution ciphers to modern mathematical algorithms including Rivest–Shamir–Adleman (RSA), elliptic curve cryptography (ECC), and advanced encryption standard (AES) that form the core of security systems, along with the major information security objectives: confidentiality, integrity, authenticity, availability, accountability, nonrepudiation, and privacy and their practical applications in protocols such as transport layer security (TLS), Internet Protocol Security (IPsec), and Secure/Multipurpose Internet Mail Extensions (S/MIME). The security of RSA, ECC, and symmetric-key ciphers has been threatened by quantum computers that exploit Shor’s and Grover’s algorithms. In response to this quantum threat, NIST has standardized post-quantum cryptographic PQC) algorithms: ML-KEM, a lattice-based key encapsulation mechanism and ML-DSA, a lattice-based digital signature scheme. This chapter surveys the development of cryptographic systems from transposition ciphers to post-quantum cryptography, examining their mathematical foundations, operational mechanisms, and respective security properties. In addition to these, the PQC algorithms have been implemented in TLS 1.3, and a comparative analysis has been performed. The study traces the history of cryptography while understanding post-quantum standards as the necessary foundation for long-term information security in the quantum era.