Key establishment among multiple participants over an insecure channel is a widely adopted cryptographic operation. However, a quantum adversary can employ Shor's algorithm, compromising most key exchange protocols based on the discrete logarithm problem. Safeguarding against such quantum attacks requires transitioning to post-quantum key establishment protocols that incorporate quantum-resistant mathematical hardness assumptions. This thesis addresses the research gap on post-quantum key exchange for multiple participants and decentralized settings. It proposes the feasible solution, Multi-Party Key Exchange (MP-KEX) protocol, to derive a conference key, implemented and evaluated using OpenSSL and liboqs cryptographic libraries. The research evaluates four cryptographic algorithm combinations of key exchange and authentication, comparing their performance, identifying the protocol's bottleneck, and addressing the formulated research questions. This thesis demonstrates that the computational cost of MP-KEX protocol is largely dictated by digital signature algorithm used, with ML-DSA being inherently slower than ECDSA-P256. On the other hand, ML-KEM is computationally fast compared to X25519 for key exchange purpose. The main bottleneck of the protocol arises from the verification phase in the naive model, whose computation time is reduced by nearly 50 % with a quorum-based verification system when the group size is large. The findings demonstrate the feasibility of MP-KEX protocol, proposing novel post-quantum key exchange protocol that provides scalable performance and empirical comparison between classical and post-quantum approaches to contributory group key establishment.
Key establishment among multiple participants over an insecure channel is a widely adopted cryptographic operation. However, a quantum adversary can employ Shor's algorithm, compromising most key exchange protocols based on the discrete logarithm problem. Safeguarding against such quantum attacks requires transitioning to post-quantum key establishment protocols that incorporate quantum-resistant mathematical hardness assumptions. This thesis addresses the research gap on post-quantum key exchange for multiple participants and decentralized settings. It proposes the feasible solution, Multi-Party Key Exchange (MP-KEX) protocol, to derive a conference key, implemented and evaluated using OpenSSL and liboqs cryptographic libraries. The research evaluates four cryptographic algorithm combinations of key exchange and authentication, comparing their performance, identifying the protocol's bottleneck, and addressing the formulated research questions. This thesis demonstrates that the computational cost of MP-KEX protocol is largely dictated by digital signature algorithm used, with ML-DSA being inherently slower than ECDSA-P256. On the other hand, ML-KEM is computationally fast compared to X25519 for key exchange purpose. The main bottleneck of the protocol arises from the verification phase in the naive model, whose computation time is reduced by nearly 50 % with a quorum-based verification system when the group size is large. The findings demonstrate the feasibility of MP-KEX protocol, proposing novel post-quantum key exchange protocol that provides scalable performance and empirical comparison between classical and post-quantum approaches to contributory group key establishment.
This thesis investigates the current state of Post-quantum cryptography (PQC) in the industry, with a particular focus on its practical deployment, integration challenges, and performance implications.The study combines a structured analysis of academic literature, standardization efforts, and industry guidance with an experimental evaluation of PQC integration in widely used security protocols. The analysis shows that, while significant progress has been made in the standardization of quantum-resistant algorithms such as ML-KEM, ML-DSA, and SLH-DSA, real-world adoption remains in an early and transitional phase. Organizations primarily focus on evaluation and pilot implementations, as deployment is constrained by interoperability issues, implementation maturity, and the complexity of migrating existing cryptographic infrastructures.To complement the conceptual analysis, experimental measurements were conducted for TLS, SSH, and IPsec to evaluate the performance impact of hybrid post-quantum cryptographic mechanisms. The results indicate that performance overhead is not uniform across components. In particular, post-quantum signature schemes introduce significant computational and network overhead, mainly due to increased key and certificate sizes. In contrast, hybrid key exchange mechanisms show only moderate performance impact across all evaluated protocols.The findings highlight that the primary challenge of PQC adoption lies not in algorithm design but in practical integration and large-scale migration. Hybrid cryptographic approaches emerge as the most viable strategy for enabling a gradual transition, balancing improved security against quantum threats with operational feasibility.Overall, this thesis demonstrates that PQC is transitioning from a theoretical research field to a practical engineering challenge, with significant implications for the future design of secure communication systems.
The advent of quantum computing poses an existential threat to contemporary cryptographic standards, particularly those securing decentralized blockchain networks and cloud infrastructures.Classical public-key cryptosystems such as RSA, ECC, and DH, which rely on factorization and discrete logarithm problems, are rendered obsolete by Shor's algorithm, necessitating the transition toward post-quantum cryptographic (PQC) solutions.This study explores the integration of PQC algorithms, including lattice-based, hash-based, code-based, multivariate, and isogeny-based cryptographic mechanisms, within blockchain-ledger technologies and cloud architectures to ensure long-term security against quantum adversaries.A comparative analysis is conducted to evaluate computational efficiency, key size implications, communication overhead, and security resilience under quantum attack models.The research highlights the adaptation of PQC within blockchain consensus mechanisms, smart contract execution, and cryptographic primitives such as digital signatures, zero-knowledge proofs, and secure multi-party computation (MPC).Additionally, it examines the impact of PQC on cloud security, addressing challenges in quantum-safe key exchange protocols, homomorphic encryption for secure computations, and cross-platform interoperability within hybrid quantum-classical cloud ecosystems.Real-world implementations and benchmarking data provide insights into the feasibility of large-scale adoption, shedding light on standardization efforts by NIST and industry consortia.The study concludes with future directions, emphasizing the need for efficient PQC algorithm optimization, lightweight cryptographic frameworks for IoT-driven blockchain applications, and scalable post-quantum identity management systems.By establishing quantum-resistant security frameworks, this research underscores the imperative need for early adoption to mitigate cryptographic vulnerabilities in the impending post-quantum era.
This study reviews post-quantum cryptographic algorithms for secure communication, focusing on standardized lattice-based schemes and their practical deployment implications. Classical public-key systems such as RSA and elliptic curve cryptography remain central to secure communication, but their long-term security is threatened by quantum algorithms capable of solving factorization and discrete logarithm problems. The study adopts a hybrid approach combining literature-based review with dataset-driven performance analysis. The empirical evaluation compares ML-KEM and ML-DSA with RSA-4096 and ECDSA-P256 using CPU benchmarking and network simulation metrics. Results indicate that ML-KEM provides substantial computational advantages over RSA-4096, making it suitable for latency-sensitive key establishment. ML-DSA also demonstrates competitive performance, especially in verification, but introduces larger signature sizes than ECDSA-P256. The analysis shows that the main deployment challenge is not computational feasibility but increased communication overhead caused by larger keys, ciphertexts, and signatures. These findings suggest that post-quantum migration requires more than direct algorithm replacement. Effective deployment should involve protocol optimization, crypto-agility, hybrid transition strategies, and context-specific parameter selection. Although the dataset focuses mainly on lattice-based algorithms, the study confirms the practical relevance of standardized post-quantum schemes for future secure communication infrastructure and identifies directions for broader evaluation across additional PQC families, including code-based, hash-based, multivariate approaches, real-world networks, and implementation-level security testing in practice contexts.
The advent of quantum computing presents a paradigm shift in modern cybersecurity, threatening the foundations of classical cryptographic systems such as RSA, ECC, and Diffie–Hellman key exchange. Quantum algorithms like Shor’s and Grover’s can efficiently break these schemes, rendering existing encryption mechanisms vulnerable and obsolete. This growing risk necessitates the development of quantum-resilient or post-quantum cryptographic (PQC) solutions that can safeguard data and computation in the era of quantum networks. Secure Multi-Party Computation (SMPC), a cornerstone of privacy-preserving computation, enables multiple entities to jointly compute a function over their private inputs without revealing them. However, its traditional security assumptions are also undermined by quantum threats. This research aims to explore and evaluate quantum-safe cryptographic protocols for integrating PQC into SMPC frameworks, thereby ensuring both confidentiality and correctness even in the presence of quantum-capable adversaries. The study focuses on lattice-based, hash-based, and code-based cryptographic primitives, analyzing their resilience, efficiency, and scalability when applied to distributed systems. A comparative framework is proposed to assess the performance and security trade-offs of different post-quantum SMPC implementations under realistic network conditions. The findings are expected to contribute to the design of a new class of cryptographic protocols capable of resisting quantum attacks, supporting the secure functioning of next-generation networks, and guiding policymakers and technologists toward practical post-quantum standardization. Ultimately, this research strengthens the bridge between theoretical cryptography and real-world cybersecurity readiness in the post-quantum era.
Group authenticated key exchange protocols (GAKE) are cryptographic tools enabling a group of several users communicating through an insecure channel to securely establish a common shared high-entropy key. In the last years, the need to design cryptographic tools which provide security in the presence of attackers with access to quantum resources has become unquestionable; the field dealing with these types of protocols is usually referred to as Post-Quantum Cryptography. The U.S. National Institute for Standards and Technology (NIST) launched in 2017 an open call to find suitable post-quantum public-key algorithms for standardization. In this work, we design a GAKE that can be instantiated with any key encapsulation mechanism (KEM) that satisfies the strong security notion IND-CCA, matching NIST’s requirements for this primitive. We have implemented our GAKE with the four finalist KEMs from the NIST process: Classic McEliece, Kyber, NTRU, and Saber, making use of the open-source library LibOQS where these algorithms are provided. We have conducted a detailed comparative performance analysis of the resulting GAKE protocols, taking into account all the parameter sets proposed in the submissions. We have also made a performance analysis of all the involved building pieces, including the four finalist KEMs. Finally, we also compare our GAKE with a previous proposal implemented with Kyber.
This paper introduces a novel Distributed Key Generation (DKG) protocol based on the Commutative Supersingular Isogeny Diffie-Hellman (CSIDH) framework for secure multi-party cryptography. Our proposed protocol is designed to address scalability and security concerns, particularly in post-quantum cryptographic systems. The main contributions include the introduction of Piecewise Verifiable Proofs (PVPs) for non-interactive zero-knowledge verification of secret shares, and the provision of rigorous security analysis, including resistance to quantum adversaries via Shor’s and Grover’s algorithms. We analyze the protocol’s efficiency, ensuring low computational overhead even in large-scale systems, and compare it with other distributed cryptographic protocols such as RSA-based and lattice-based schemes. Through mathematical proofs and complexity analysis, we demonstrate that our protocol offers enhanced security, efficiency, and scalability in a post-quantum environment. The results presented in this paper provide a strong foundation for implementing secure multi-party computations in quantum-resistant systems.