Post-Quantum Cryptography Without Public Keys: Symmetric Trust Models and Smart Cards

Vasiliki Diamantopoulou, Κωνσταντίνος Μαλιάτσος, Stefanos Vasileiadis +3 more

Akinori Hosoyamada

Abdullah Aydeger, Engin Zeydan, Awaneesh Kumar Yadav +1 more

The impending threat posed by quantum-capable adversaries necessitates a secure and practical transition of Public Key Infrastructures (PKIs) to support post-quantum cryptography (PQC). This paper addresses the multifaceted challenges of integrating PQC into existing PKI ecosystems by examining novel cryptographic combiners and hybrid certificate designs that can provide quantum-resistant security. We assess the performance, compatibility, and security of these hybrid certificates across standard communication protocols such as TLS, considering variations in root and intermediate certification paths. In addition, we introduce key management procedures that cover signature generation, validation, and lifecycle considerations under both software and hardware constraints. Beyond X.509, alternative trust models and certificate mechanisms are also analyzed for specialized domains, including IoT, firmware signing, and smart cards.

光倫 細山田, Akinori Hosoyamada

Neha W. Bandabuche, Tanaya U. Manjre

ABSTARCT The rapid proliferation of smart home Internet of Things (IoT) technologies has transformed residential environments through intelligent automation, remote monitoring, and data driven decision making. Alongside these benefits, security risks have intensified due to advances in large scale quantum computing, which threaten the cryptographic foundations of current IoT systems. Widely deployed public key algorithms such as RSA and Elliptic Curve Cryptography are vulnerable to quantum attacks enabled by Shor’s algorithm, raising serious concerns regarding long term confidentiality, authentication, and trust in smart home ecosystems. To address this challenge, two major quantum resilient security paradigms have emerged: Post Quantum Cryptography (PQC) and Quantum Key Distribution (QKD). This paper presents a structured comparative study of PQC and QKD within smart home IoT environments, evaluating architectural compatibility, computational and energy constraints, scalability, deployment cost, communication models, and security guarantees. Realistic smart home scenarios including smart locks, surveillance cameras, and resource constrained sensor networks are examined to assess practical feasibility. The analysis demonstrates that while QKD offers information theoretic security under ideal conditions, its reliance on specialized quantum hardware and dedicated infrastructure makes it unsuitable for consumer smart homes. In contrast, PQC provides a scalable, software based, and cost effective approach that integrates seamlessly. Keywords: Post-Quantum Cryptography, Quantum Key Distribution, Smart Home IoT, Quantum Security, IoT Cryptography.

Tooba Qasim, Vasilios A. Siris, Izak Oosthuizen +2 more

Biometric authentication has become integral to digital identity systems, particularly in smart cities where it enables secure access to services across governance, transportation, and public infrastructure. Centralised architectures, though widely used, pose privacy and scalability challenges due to the aggregation of sensitive biometric data. Decentralised identity frameworks offer better data sovereignty and eliminate single points of failure but introduce new security concerns, particularly around mutual trust among distributed devices. In such environments, biometric sensors and verification agents must authenticate one another before sharing sensitive biometric data. Existing authentication schemes rely on classical public key infrastructure, which is increasingly susceptible to quantum attacks. This work addresses this gap by proposing a quantum-secure communication protocol for decentralised biometric systems, built upon an enhanced Quantum Key Distribution (QKD) system. The protocol incorporates quantum-resilient authentication at both the classical and quantum layers of QKD: post-quantum cryptography (PQC) is used to secure the classical channel, while authentication qubits verify the integrity of the quantum channel. Once trust is established, QKD generates symmetric keys for encrypting biometric data in transit. Qiskit-based simulations show a key generation rate of 15 bits/sec and 89% efficiency. This layered, quantum-resilient approach offers scalable, robust authentication for next-generation smart city infrastructures.