This work presents the implementation of a quantum-enabled Secure Multi-Party Computation (SMC) service applied to two medical use cases and demonstrated on a Quantum Key Distribution (QKD) network deployed in Aveiro, utilizing both research and commercial QKD devices. We show the integration of quantum resources into the execution of SMC protocols by using quantum-generated oblivious keys, and also an overview of the generic framework for deploying SMC services. At the end, the results demonstrate the feasibility of the proposed use cases, highlighting the need for continued research into the integration of quantum Oblivious Transfer (OT) and SMC services within QKD networks.
This work presents the implementation of a quantum-enabled Secure Multi-Party Computation (SMC) service applied to two medical use cases and demonstrated on a Quantum Key Distribution (QKD) network deployed in Aveiro, utilizing both research and commercial QKD devices. We show the integration of quantum resources into the execution of SMC protocols by using quantum-generated oblivious keys, and also an overview of the generic framework for deploying SMC services. At the end, the results demonstrate the feasibility of the proposed use cases, highlighting the need for continued research into the integration of quantum Oblivious Transfer (OT) and SMC services within QKD networks.
The development of an efficient quantum computer with enough qubits will benefit humanity, but it will also pose a threat to most public cryptography. Even information secured by public cryptography primitives before the advent of this quantum computer falls under this threat since large quantities of data can be eavesdropped and stored by a malicious actor in hopes of someday having access to a quantum computer that will enable the compromising of the data. PQC and QKD are the main answers to this threat. Even though PQC algorithms aim to transition the existing PKI to be quantum-safe, they still offer the same security guarantees as today’s algorithms offer under a classical setting but rely on a new set of mathematical problems believed not to be vulnerable to a quantum computer. PQC is considered by many to be the main solution for most use cases because its integration carries little to no monetary costs, it calls for no major infrastructure updates, and it can be applied to all applications of public cryptography such as key exchanges and digital signatures. On the other hand, QKD leverages the fundamental laws of quantum mechanics to securely distribute cryptographic keys between remote parties. This solution offers information theoretical security and enables perfect forward secrecy, but it demands the development of a whole new type of network, a QKDN, to normalize the generation, distribution, and usage of quantumgenerated symmetric and oblivious keys. This dissertation presents the approach, implementation, and discussion of two quantum-enabled hybrid services, one applied for secure communications, and the other for secure computations. While the main focus was on the integration of quantum-generated keys into these services, PQC, and classical cryptography were also leveraged as recommended by EU’s commission. Regarding secure communications, a key rotator was developed showing how an existing highly deployed VPN solution can be quantum-enabled in a non-intrusive manner with zero downtime and no performance impact. Regarding secure computations, it was explored how quantum-generated oblivious keys can be leveraged in existing OT-based SMC protocols, integrating the solution into an opensource SMC library, its usage in an SMC service infrastructure, and showcased in the scope of two use cases in the fields of medicine and defense. These services were used in the context of a 5-node test network deployed in Aveiro leveraging both research and commercial QKD Modules, demonstrating the viability of the solutions.
This paper presents a novel protocol for secure multi-party computation (SMC) leveraging quantum networks and quantum key distribution (QKD). The core idea is to utilize the inherent security properties of QKD and quantum states to construct a secure computational environment, safeguarding the privacy of participants during distributed calculations. The protocol, termed Quantum Network-Based SMC (QN-SMC), employs a layered approach combining a classical pre-processing phase with a quantum computation phase secured by QKD. We detail the protocol's architecture, mathematical formulations, and security guarantees. The key contributions of this work lie in the integration of QKD into the SMC framework, enabling computation on distributed quantum states while maintaining confidentiality and integrity. We explore the feasibility and potential impact of this approach for applications requiring secure distributed processing within a quantum network. The protocol's performance is analyzed in terms of key distribution rates, computational overhead, and security levels.
Secure Multiparty Computation (SMC) allows multiple individuals, each having their own private data, to perform a computation task without unveiling their data to others. SMC has a wide range of real-life use cases, including machine learning, vehicular networks, banking, defense, and healthcare. However, classical SMC implementations face significant challenges related to both security and efficiency. Classical SMC protocols rely on public-key cryptographic methods, which introduce substantial computational and communication costs. Additionally, these protocols are vulnerable to quantum computer attacks that have the potential to break certain types of cryptographic ciphers, notably those used in RSA. In this thesis, we tackle these challenges by enhancing the security and efficiency of SMC implementations through quantum communication and quantum computing. Quantum communication contributes to enhancing security, while quantum computing, by leveraging quantum processors, offers the potential to significantly improve efficiency. In the quantum communication approach, we propose a Quantum SMC (QSMC) framework that leverages three advanced quantum communication technologies - Quantum Random Number Generation (QRNG), Quantum Key Distribution (QKD), and Quantum Oblivious Key Distribution (QOKD)—in conjunction with a Key Management System (KMS) and the Faster Malicious Arithmetic Secure Computation with Oblivious Transfer (MASCOT) protocol. Exploiting the proposed framework, we implement two essential SMC use cases: Safe Route Departure (SRD) and Drug Solubility Prediction (DSP), applied to vehicular networks and drug discovery, respectively. The SRD facilitates secure vehicular communication, allowing vehicles to safely change lanes and exit routes without compromising sensitive information. We achieved a 97% improvement in efficiency by significantly reducing communication costs, while incurring a moderate 42% increase in computational cost. The DSP, on the other hand, empowers pharmaceutical companies to collaboratively train a Graph Convolutional Network (GCN) to predict the solubility of drug molecules while fully safeguarding their private datasets. During training, the loss function across all parties averaged 0.0046, while the Mean Squared Error (MSE) on the test set is 1.2, indicating effective model learning. Afterwards, exploiting the quantum computing approach, we propose two novel SMC protocols for Boolean function computation resorting to the Measurement Based Quantum Computing (MBQC) approach and single qubits. We implement the proposed schemes on the IBM Qiskit platform and validate their feasibility.
Nowadays the need of securely transmitting information has become crucial due to the increasing threat of cyberattacks. Quantum Key Distribution (QKD) guarantees information-theoretic security in the transmission of secure keys between two trusted parties, leveraging the laws of quantum mechanics. In more general mistrustful communication scenarios, alternative protocols, often referred to as beyond-QKD protocols, are employed [1]. A notable example is oblivious transfer, a cryptographic primitive that supports secure multiparty computation (SMC).
We analyze the use of a Quantum Key Distribution (QKD) system to generate and distribute oblivious keys. Oblivious keys can be used to implement secure multiparty computation services. After defining oblivious keys, we show how they can be reduced to symmetric keys and used to implement secure links, and how they can also be used to implement secure computation services. Oblivious keys can also be reversed. In this context, we analyze the advantages of using quantum resources to generate oblivious keys. Particularly, we analyze a protocol to generate oblivious keys, considering both the efficiency and security of the process. We show that by using QKD, we can simultaneously obtain an efficient and quantum-resistant solution to generate and distribute oblivious keys. Finally, we discuss a field trial where a quantum secure multiparty computation service for calculating phylogenetic trees was implemented in the Quantum Madrid Network.
We analyse a Secure Multiparty Computation (SMC) system assisted with quantum communication technologies. This SMC system is designed to compute phylogenetic trees of SARS-CoV-2 genomes. It adapts a distance-based method known as the Unweighted Pair Group Method with Arithmetic mean (UPGMA) algorithm into a private setting where the sequences owned by each party are not disclosed to the other members present in the protocol. Our main contribution lies on the integration of two quantum communication systems (quantum oblivious transfer and quantum key distribution) with libScapi implementation of the Yao secure computation protocol. This system significantly improves security when compared to its classical implementation since both quantum oblivious transfer and quantum key distribution modules are robust under a quantum computer attack. This system is designed to be compatible with current quantum networks.