The development of quantum computers has been progressing rapidly in recent years based on principles fundamentally different from those of conventional computers.It is known that they can be used to break many of the encryption schemes that are now in actual use.To counter this threat, there is a need for "postquantum cryptography" that cannot be broken even by quantum computers.In this interview, we asked NTT Distinguished Researcher Takashi Yamakawa to tell about his research in solving such social issues using cryptography.
The development of quantum computers has been progressing rapidly in recent years based on principles fundamentally different from those of conventional computers.It is known that they can be used to break many of the encryption schemes that are now in actual use.To counter this threat, there is a need for "postquantum cryptography" that cannot be broken even by quantum computers.In this interview, we asked NTT Distinguished Researcher Takashi Yamakawa to tell about his research in solving such social issues using cryptography.
Quantum computing is a distinct field of computational science that uses principles from quantum mechanics to tackle problems that traditional computing struggles with in speed, size, and complexity. Classical cryptography relies on the complexity of mathematical problems such as large-number factorization, but quantum systems can solve them much faster. This threat necessitates the development and implementation of cryptographic methods resistant to attacks from both classical and quantum systems, known as Post-Quantum Cryptography (PQC). Strong cryptographic algorithms are crucial to counter vulnerabilities in pre-quantum systems. This paper reviews the challenges and solutions for securing communication amid advances in quantum computing. It stresses the urgent need to shift from classical cryptographic systems, which are susceptible to quantum threats, to PQC. The discussion includes theoretical frameworks and practical implementations, covering quantum principles, Quantum Key Distribution (QKD), and standard PQC algorithms. Additionally, it briefly introduces Number Theoretic Transform (NTT) concepts, which enhance polynomial multiplication speed—an essential operation in PQC—by reducing computational complexity from O( n 2 ) to O( nlogn ) . The paper demonstrates the NTT/Inverse Number Theoretic Transform (INTT) hardware core in Python, focusing on its application to ML-KEM Polynomial arithmetic. Results indicate that NTT outperforms INTT in execution time and throughput. The paper concludes with an overview of security assumptions, cryptanalysis, and the current status of standardization.
Cryptographic technology based on fundamental theories that are unshakeable even in the era of quantum computers -Could you tell us about your current research?I became an NTT Fellow in 2022, and am research-ing cryptography under the new structure of the Abe Research Laboratory.Research on cryptography atNTT is roughly categorized into three areas based on periods in chronological order: "present," "near future," and "distant future" (Fig. 1).The critical points concerning these categorizations are whether the period is before or after the advent of general-purpose Pursuing Fundamental Theory and Applied Technology of Cryptography That Is Secure in an Environment in Which Quantum Computers Are WidespreadFront-line Researchers
Triggered by the case that a government employee successfully forged a bank card in 1982, NTT established the first research group on cryptography around the same time.NTT Secure Platform Laboratories has contributed to building a firm theoretical ground for cryptography while developing cryptographic technologies that can respond to the changes in evolving communication and computing environments.In this article, research activities of NTT Secure Platform Laboratories on cryptography and information security technologies-in preparation for the emergence of rapidly developing quantum computers-are discussed.
The threats are existential to the traditional cryptosystems of public keys, including RSA, Diffie-Hellman, and elliptic curve cryptography (ECC), due to the rapid progress in quantum computing. Such algorithms as the Shor and Grover algorithms prove that as soon as large scale quantum computers are achieved, these classical cryptographic protocols will not provide any privacy and integrity to online communication. This has created an emergency to find post-quantum cryptography (PQC), or quantum-safe cryptography, which will resist attacks by both classical and quantum attackers. The paper is a review of the latest research and development in post-quantum cryptographic algorithms and their implementation in current security systems. We organize quantum-safe methods into significant organizations such as lattice-based, hash-based, multivariate polynomial-based and code-based encrypted communications. Each type has been evaluated critically based on computational efficiency, key sizes, speed of encryption/decryption and security proofs. The survey also examines the current standardization activities happening in the world and especially the U.S. National Institute of Standards and Technology (NIST) PQC competition, which lists candidate algorithms that have advanced to standard adoption. Besides this, the paper addresses hybrid cryptographic designs that use both classical and post-quantum bases in ensuring a seamless migration in the transition phase. Internet security protocols like TLS, VPNs and blockchain consensus as applications of PQC are examined in detail. Lastly, we pinpoint open research issues, which include creating lightweight PQC to support resource-constrained IoT devices, balancing performance and strong security assurances, and interoperability between the new PQC algorithms and existing infrastructures. Through detailed survey we inform the future of researchers, practitioners, and policymakers on the preparation of the post-quantum era of secure digital communications.
As quantum computing progresses towards practical realization, the security of existing cryptographic protocols, such as RSA and Elliptic Curve Cryptography (ECC), faces unprecedented risks. Quantum algorithms like Shor's Algorithm threaten to undermine the security of these widely used encryption schemes, necessitating the development of quantum-resistant alternatives. This paper explores the vulnerabilities of current cryptographic protocols in the quantum era and investigates quantum-safe cryptographic techniques such as lattice-based, hash-based, and code-based cryptography. Additionally, we delve into Quantum Key Distribution (QKD), a method that leverages the principles of quantum mechanics to securely distribute cryptographic keys, ensuring secure communication even in the presence of quantum adversaries. The integration of QKD with post-quantum cryptographic algorithms is proposed as a robust approach to future-proofing cybersecurity. The paper concludes with a discussion of practical challenges in implementing quantum-safe systems and highlights future research directions to strengthen cryptographic resilience against quantum threats.
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.