The security of conventional public-key cryptography schemes is based on mathematical problems which are considered to be infeasible to solve by classical computers in a reasonable amount of time. However, the rise of quantum computers might break this security in the future. Post-quantum cryptography (PQC) aims to achieve secure schemes which are resistant against attacks assisted by quantum computers. Public-key cryptography refers to asymmetric cryptography in which encryption is done with a public key and decryption is done with a private key. Characteristic properties of public-key cryptography include the possibility to derive the private key from public information by solving some presumably hard problem. The hardness of the problem constitutes the basis for the system's security. In the post-quantum era, the security must be based on problems that are too hard to solve even for quantum computers. In this thesis, we will study lattice-based cryptography which is believed to serve as a good candidate for secure post-quantum public-key cryptography. Our main attention is in the problem of learning with errors, which is in the base of some lattice-based schemes and is linked to the hard problem of finding short vectors in a lattice.
The security of conventional public-key cryptography schemes is based on mathematical problems which are considered to be infeasible to solve by classical computers in a reasonable amount of time. However, the rise of quantum computers might break this security in the future. Post-quantum cryptography (PQC) aims to achieve secure schemes which are resistant against attacks assisted by quantum computers. Public-key cryptography refers to asymmetric cryptography in which encryption is done with a public key and decryption is done with a private key. Characteristic properties of public-key cryptography include the possibility to derive the private key from public information by solving some presumably hard problem. The hardness of the problem constitutes the basis for the system's security. In the post-quantum era, the security must be based on problems that are too hard to solve even for quantum computers. In this thesis, we will study lattice-based cryptography which is believed to serve as a good candidate for secure post-quantum public-key cryptography. Our main attention is in the problem of learning with errors, which is in the base of some lattice-based schemes and is linked to the hard problem of finding short vectors in a lattice.
The imminent threat posed by the development of cryptographically relevant quantum computers necessitates a paradigm shift in public-key cryptography. Traditional cryptosystems like RSA and Elliptic Curve Cryptography (ECC), which underpin global digital security, are vulnerable to quantum algorithms such as Shor's algorithm. This vulnerability mandates a proactive migration to post-quantum cryptography (PQC) to secure long-term sensitive data. Among the various candidates for post-quantum security, lattice-based cryptography has emerged as a particularly promising and robust solution. This paper explores the fundamental principles of lattice-based cryptography, detailing its security foundations rooted in the presumed hardness of lattice problems like the Short Integer Solution (SIS) and Learning With Errors (LWE) problems. We review the significant progress in the field, including its selection as a primary candidate in the NIST Post-Quantum Cryptography standardization process. We discuss its advantages in terms of provable security, versatility, and potential for efficient implementation across diverse platforms, from cloud infrastructure to the Internet of Things (IoT). We also address the practical implications and challenges of its deployment, asserting its indispensable role in fortifying public-key security against future quantum attacks, thereby establishing it as a post-quantum imperative.
The advent of quantum computing poses a significant existential threat to current public-key cryptographic systems, most notably RSA and Elliptic Curve Cryptography (ECC), which rely on the presumed hardness of integer factorization and discrete logarithm problems. Shor's algorithm, a quantum algorithm, can efficiently solve these problems, rendering classical asymmetric primitives insecure. This paper addresses the imperative need for post-quantum cryptography (PQC) by exploring lattice-based constructs as robust alternatives for asymmetric primitives. We provide a comprehensive overview of the fundamental mathematical problems underlying lattice-based cryptography, such as the Shortest Vector Problem (SVP), Closest Vector Problem (CVP), Learning With Errors (LWE), and Ring Learning With Errors (RLWE). The paper surveys prominent lattice-based schemes, including NTRU, CRYSTALS-Kyber, and CRYSTALS-Dilithium, analyzing their security foundations, performance characteristics, and the extent to which they offer a viable "post-quantum RSA." We delve into the methodology of constructing these primitives, discuss their resilience against both classical and quantum attacks, and evaluate their practical implications for key sizes, computational efficiency, and deployment challenges. Our analysis highlights that lattice-based cryptography, particularly the NIST-standardized schemes, presents a strong candidate for securing digital communications in the quantum era, offering provable security rooted in worst-case to average-case reductions for lattice problems.
The advent of large-scale quantum computers poses a profound and imminent threat to the security foundations of modern cryptography. Widely deployed public-key cryptosystems, such as RSA and Elliptic Curve Cryptography (ECC), rely on problems like integer factorization and discrete logarithms, which Shor's algorithm can efficiently solve. This necessitates a proactive transition to post-quantum cryptography (PQC). Among leading candidates, lattice-based cryptography stands out due to its robust security guarantees, based on hard problems lacking known efficient quantum solutions, and structural properties facilitating efficient implementation. This paper explores the fundamental principles of lattice-based cryptography, detailing underlying mathematical hard problems such as the Shortest Vector Problem (SVP) and Learning With Errors (LWE). We review the evolution of lattice-based schemes, from early constructions to contemporary candidates like Kyber and Dilithium, emphasizing their suitability for Key Encapsulation Mechanisms (KEMs) and Digital Signature Schemes (DSS). Furthermore, we analyze their performance characteristics, security assumptions, and resilience against classical and quantum attacks, providing a critical comparison with other PQC families. This comprehensive overview, structured through a systematic critical analysis framework, highlights the ascendancy of lattice-based cryptography as a cornerstone for future quantum-resistant security infrastructure, offering theoretical underpinnings, practical implications, and actionable future research directions for a post-quantum world.
The advent of quantum computing poses a significant threat to the security of current asymmetric cryptographic systems, which underpin much of modern digital communication and security. These systems, predominantly RSA and Elliptic Curve Cryptography (ECC), rely on the computational hardness of mathematical problems such as integer factorization and the discrete logarithm problem. Shor's algorithm, a quantum algorithm, demonstrates the ability to efficiently solve these problems, rendering classical public-key cryptography vulnerable to attacks by sufficiently powerful quantum computers. This paper argues for and thoroughly examines the strategic imperative of transitioning from these classical cryptographic foundations to a new paradigm based on lattices, which are believed to be resistant to quantum attacks. We delve into the fundamental mathematical problems underlying lattice-based cryptography, such as the Shortest Vector Problem (SVP) and the Learning With Errors (LWE) problem, whose worst-case hardness is leveraged to achieve cryptographic security. A comprehensive literature review is provided, tracing the evolution of quantum threats and the emergence of lattice-based schemes. The methodology details the construction principles of prominent lattice-based cryptosystems. Results demonstrate their theoretical security against quantum adversaries and highlight their practical attributes, including compact key sizes and competitive performance. The discussion section contextualizes lattice-based cryptography within the broader landscape of post-quantum candidates, examining their strengths, weaknesses, and the ongoing standardization efforts by organizations like NIST. We conclude that lattice-based cryptography offers a robust and promising foundation for building resilient asymmetric cryptographic systems in the post-quantum era, ensuring the long-term security of digital information through a necessary re-architecture of cryptographic primitives.
The imminent threat posed by the advent of quantum computers to contemporary public-key cryptographic schemes, such as RSA and Elliptic Curve Cryptography (ECC), necessitates a fundamental shift in cryptographic paradigms. Shor's algorithm, specifically, presents a catastrophic vulnerability to these foundational security protocols, underpinning global digital communication and commerce. This paper provides a comprehensive exploration into lattice-based cryptography as a robust and promising candidate for a post-quantum cryptographic future. We delve into the mathematical underpinnings of lattices, elucidating the computational hardness of problems like the Shortest Vector Problem (SVP) and the Learning With Errors (LWE) problem, which form the bedrock of their security. The paper reviews the historical development of lattice-based schemes, their theoretical advantages, and their practical implications, particularly in the context of the ongoing NIST Post-Quantum Cryptography standardization process. We analyze the construction of key encapsulation mechanisms (KEMs) and digital signature schemes from lattice problems, comparing their performance characteristics and security guarantees against classical methods. The work argues that lattice-based cryptography offers a compelling alternative to RSA, providing not only quantum resistance but also presenting attractive features in terms of efficiency, design simplicity, and versatility for various cryptographic primitives. The discussion extends to implementation challenges, security analysis, and the broader implications for the global migration towards a quantum-secure cryptographic infrastructure.
Cryptography is important for data confidentiality, integrity, and authentication. Public key cryptosystems allow for the encryption and decryption of data using two different keys, one that is public and one that is private. This is beneficial because there is no need to securely distribute a secret key. However, the development of quantum computers implies that many public-key cryptosystems for which security depends on the hardness of solving math problems will no longer be secure. It is important to develop systems that have harder math problems which cannot be solved by a quantum computer. In this project, two public-key cryptosystems which are candidates for quantum-resistance were implemented using Rust. The security of the McEliece system is based on the hardness of decoding a linear code which is an NP-hard problem, and the security of the Regev system is based off of the Learning with Errors problem which is as hard as several worst-case lattice problems [1], [2]. Tests were run to verify the correctness of the implemented systems and experiments were run to analyze the cost of replacing pre-quantum systems with post- quantum systems.