Quantum-secure Software Network Environments for Telco Operators
Rubén B. Méndez, Mattin Antartiko Elorza Forcada, Andrés Ruiz-Chamorro, Grazzia D'Onghia, Ramon Querol, Javier Faba, Victor Hernando Fernandez, Luis F. Gonzalez Blazquez, Juan Pedro Brito Méndez, Vicente Martin, Antonio Pastor Perales
The transition towards quantum-safe secure communications requires current network infrastructures to support the coexistence of multiple cryptographic technologies. In this context, crypto-agility becomes a key requirement, enabling the coordinated use of Quantum Key Distribution (QKD), Post-Quantum Cryptography (PQC), and classical cryptographic mechanisms during a progressive migration process. This paper presents a general, standards-based architecture for crypto-agile IPsec service provisioning in Software-Defined Networking (SDN) environments. The proposal combines modular functional blocks that support the integration of QKD-, PQC-,and classical-derived key material under a common operational framework. The architecture builds on existing specifications, including RFC 9061 and ETSI GS QKD 004. Rather than focusing on implementation details or performance evaluation, this work describes the needs addressed by the architecture, its main components, and the operational workflows supporting secure tunnel establishment, rekeying, and attestation-related actions.
The transition towards quantum-safe secure communications requires current network infrastructures to support the coexistence of multiple cryptographic technologies. In this context, crypto-agility becomes a key requirement, enabling the coordinated use of Quantum Key Distribution (QKD), Post-Quantum Cryptography (PQC), and classical cryptographic mechanisms during a progressive migration process. This paper presents a general, standards-based architecture for crypto-agile IPsec service provisioning in Software-Defined Networking (SDN) environments. The proposal combines modular functional blocks that support the integration of QKD-, PQC-,and classical-derived key material under a common operational framework. The architecture builds on existing specifications, including RFC 9061 and ETSI GS QKD 004. Rather than focusing on implementation details or performance evaluation, this work describes the needs addressed by the architecture, its main components, and the operational workflows supporting secure tunnel establishment, rekeying, and attestation-related actions.
The transition towards quantum-safe secure communications requires current network infrastructures to support the coexistence of multiple cryptographic technologies. In this context, crypto-agility becomes a key requirement, enabling the coordinated use of Quantum Key Distribution (QKD), PostQuantum Cryptography (PQC), and classical cryptographic mechanisms during a progressive migration process. This paper presents a general, standards-based architecture for crypto-agile IPsec service provisioning in Software-Defined Networking (SDN) environments. The proposal combines modular functional blocks that support the integration of QKD-, PQC-, and classical-derived key material under a common operational framework. The architecture builds on existing specifications, including RFC 9061 and ETSI GS QKD 004. Rather thanfocusing on implementation details or performance evaluation, this work describes the needs addressed by the architecture, its main components, and the operational workflows supporting secure tunnel establishment, rekeying, and attestation-related actions.
The growing dependence on digital communications underscores the need to protect data as it travels through the network. Internet Protocol Security (IPsec) plays a central role, providing a robust framework to ensure the confidentiality, integrity, and authenticity of transmitted data. However, advances in Quantum Computing pose a significant threat to current public-key cryptographic schemes by enabling efficient solutions to factoring and discrete logarithm problems. A promising solution also arises from the quantum domain. Quantum Key Distribution (QKD) provides a security layer immune to any computational attacks, whether quantum or classical. While the rapid adoption of quantum-safe technologies is highly desirable, it is equally important to ensure the resilience of existing trusted infrastructures, as the introduction of novel technologies may also entail unforeseen challenges. Enabling an evolutionary path that brings our current security infrastructure to a quantum-safe one, protected against both present and future threats, is thus very important. This work proposes a solution that integrates emerging quantum technologies into the existing security and communications infrastructure to ensure long-term protection. We focus on IPsec —one of the most widely deployed security protocols— and combine it with Software-Defined Networking (SDN) and QKD to construct a novel network security infrastructure that is resilient against both classical and quantum computational threats. Building upon recent standardization initiatives and operational tools for QKD integration, we demonstrate advanced capabilities -including rekeying and secure key transport- on a field deployed QKD network operating within a shared quantum-classical production infrastructure.
Cloud infrastructures moving toward post-quantum cryptography present both opportunities and risks since safe workload interoperability is made more difficult by disparate providers' uneven key management. In this study, a crypto-agile zero-trust access architecture for multi-cloud environments is presented, utilizing software-defined networking (SDN) to coordinate quantum key distribution (QKD) and post-quantum cryptography (PQC) for session security. The architecture incorporates a policy-driven controller that uses programmable data planes for micro-segmentation and continuous verification to dynamically choose ML-KEM or QKD-derived keys for each transaction. The system includes automated failover between PQC and QKD to guarantee resilience, preserving secure connectivity in the event of link failure or resource exhaustion. QKD-PQC failover under adversarial stress, flow-level path enforcement via P4, and TLS 1.3 handshakes with PQC are all demonstrated using a simulation prototype. The results demonstrate that SDN-based orchestration can maintain performance and uphold zero-trust principles, while also highlighting the viability of quantifying PQC overhead in real-time cloud scenarios. This establishes the framework as a workable route to multi-cloud security that is quantum robust.
The emergence of Cryptographically Relevant Quantum Computers (CRQCs) presents a critical threat to classical cryptographic systems, particularly widely adopted protocols such as RSA, Diffie-Hellman (DH), and Elliptic Curve Cryptography (ECC). Given their extensive use in the financial sector, the advent of quantum adversaries compels banking institutions to proactively develop and adopt quantum-safe communication mechanisms. This paper introduces a hybrid quantum-safe architecture, orchestrated via Software-Defined Networking (SDN) key distribution. The proposed framework enables the early integration of Classical Cryptography (CC), Quantum Key Distribution (QKD), and Post-Quantum Cryptography (PQC) within a Dynamic Multipoint Virtual Private Network (DMVPN) environment, providing highly scalable, full-mesh, site-to-site encrypted communications for enterprise networks. This is particularly relevant at a time when PQC algorithms have not yet been incorporated into finalized IPsec standards. The architecture has been validated across a five-node testbed comprising three physical nodes within a campus network in Madrid and two private-cloud nodes located in the north of Spain and Mexico. The deployment leverages a heterogeneous mix of physical and virtual devices, diverse technology providers, Discrete Variable QKD (DV-QKD) and Continuous Variable QKD (CV-QKD) implementations, and mutually incompatible key-delivery interfaces (ETSI004, ETSI014 and Cisco SKIP), demonstrating flexibility, scalability, and interoperability across environments. Through this framework, we demonstrate that quantum-safe communication in financial networks is not only technically feasible but also scalable, interoperable, and resilient. The proposed architecture establishes a robust, flexible, and future-proof foundation for secure financial communications in the era of quantum computing.
Shor's algorithm efficiently solves factoring and discrete logarithm problems using quantum computers, compromising all public key schemes used today. These schemes rely on assumptions on their computational complexity, which quantum computers can easily bypass. The solutions have to come from new algorithms - called Post-Quantum Cryptography (PQC) - or from new methods, such as Quantum Key Distribution (QKD). The former replicate the computational security ideas of classical public key algorithms, while the latter recurs to use the quantum properties of nature, which also brings a mathematical security proof, potentially offering Information-Theoretic Security. To secure data in the future, we must adopt these paradigms. With the speed of quantum computing advancements, the transition to quantum-safe cryptography within the next decade is critical. Delays could expose long-lived confidential data, as current encryption may be broken before its value expires. However, the shift must balance the adoption of new technologies with maintaining proven systems to protect against present and future threats. In this work, we have selected Transport Layer Security, one of the most widely used protocols, as the foundation to hybridize classical, quantum, and post-quantum cryptography in a way suitable for broad adoption in Software-Defined Networking, the most flexible networking paradigm that has been used to deploy integrated quantum-classical networks. To this end, we use standards for QKD key extraction and SDN integration. The purposed implementation is based on the latest version of TLS and demonstrates advanced capabilities such as rekeying and key transport across a large QKD network, while supporting crypto-agility and maintaining backward compatibility through the use of ciphersuites. The performance of this approach has been demonstrated using a deployed production infrastructure.
Abstract: This study advances a unifying systems perspective on quantum-safe network security by synthesizing recent progress in quantum cryptography with practical integration patterns across carrier-grade infrastructures. Concept analysis distinguishes the roles of quantum key distribution (QKD), device-independent variants, quantum authentication, and post-quantum cryptography (PQC) within zero-trust architectures. Building on this, a layered framework—spanning physical/entanglement resources, key management, crypto-agility, control plane orchestration, and policy/compliance—is articulated to support end-to-end, composable guarantees. The problem addressed is the realization of verifiable, quantum-resilient security under operational constraints involving latency, key-rate variability, and heterogeneous trust assumptions. Methodology combines a structured literature synthesis with formal composability mapping to universal composability principles, adversarial threat modeling for quantum-enabled attackers, and testbed/simulation evaluation of hybrid QKD–PQC pipelines across L2–L3 segments and 5G/6G backhaul scenarios. Key results indicate that (i) selective QKD deployment on high-value links coupled with PQC at endpoints enhances resilience while preserving crypto-agility; (ii) automated key-lifecycle orchestration reduces exposure windows; and (iii) device-independent assurances strengthen guarantees where trust relaxation is necessary. The impact is a deployment-ready reference architecture, measurable integration metrics, and guidance aligned with emerging standards for critical infrastructure and national networks. The implications extend to procurement, compliance, and roadmap planning for quantum-era network security. Keywords: quantum-safe cryptography, quantum key distribution (QKD), post-quantum cryptography (PQC), hybrid QKD–PQC, composable security, device-independent QKD, zero-trust networks, key management and orchestration, 5G/6G backhaul, network security architecture, standards and interoperability