Abstract Secure Multiparty Computation (SMC) enables multiple parties to cooperate securely without compromising their privacy. SMC has the potential to offer solutions for privacy obstacles in vehicular networks. However, classical SMC implementations suffer from efficiency and security challenges. To address this problem, two quantum communication technologies, Quantum Key Distribution (QKD) and Quantum Oblivious Key Distribution were utilised. These technologies supply symmetric and oblivious keys respectively, allowing fast and secure inter‐vehicular communications. These quantum technologies are integrated with the Faster Malicious Arithmetic Secure Computation with Oblivious Transfer (MASCOT) protocol to form a Quantum Secure Multiparty Computation (QSMC) platform. A lane change service is implemented in which vehicles broadcast private information about their intention to exit the highway. The proposed QSMC approach provides unconditional security even against quantum computer attacks. Moreover, the communication cost of the quantum approach for the lane change use case has decreased by 97% when compared to the classical implementation. However, the computation cost has increased by 42%. For open space scenarios, the reduction in communication cost is especially important, because it conserves bandwidth in the free‐space radio channel, outweighing the increase in computation cost.
Abstract Secure Multiparty Computation (SMC) enables multiple parties to cooperate securely without compromising their privacy. SMC has the potential to offer solutions for privacy obstacles in vehicular networks. However, classical SMC implementations suffer from efficiency and security challenges. To address this problem, two quantum communication technologies, Quantum Key Distribution (QKD) and Quantum Oblivious Key Distribution were utilised. These technologies supply symmetric and oblivious keys respectively, allowing fast and secure inter‐vehicular communications. These quantum technologies are integrated with the Faster Malicious Arithmetic Secure Computation with Oblivious Transfer (MASCOT) protocol to form a Quantum Secure Multiparty Computation (QSMC) platform. A lane change service is implemented in which vehicles broadcast private information about their intention to exit the highway. The proposed QSMC approach provides unconditional security even against quantum computer attacks. Moreover, the communication cost of the quantum approach for the lane change use case has decreased by 97% when compared to the classical implementation. However, the computation cost has increased by 42%. For open space scenarios, the reduction in communication cost is especially important, because it conserves bandwidth in the free‐space radio channel, outweighing the increase in computation cost.
Quantum Secure Multiparty Computation (QSMC) is a technology that takes the advantage of quantum features allowing multiple parties to communicate in a secure and efficient manner while preserving their privacy. Using QSMC technology, we implement a collision warning use case in which vehicles can freely broadcast information while preserving the privacy of their confidential data. We integrate two quantum technologies namely Quantum Key Distribution (QKD) and Quantum Oblivious Key Distribution (QOKD) with the Malicious Arithmetic Secure Computation with Oblivious Transfer (MASCOT) protocol to implement a secure and efficient QSMC platform. This quantum approach significantly improves efficiency and security when we compare it with the classical implementation as both used quantum technologies (QKD and QOKD) are robust against quantum computer attacks.
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.
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.
Many cryptographic techniques have been proposed to conceive a secure and privacy-oriented vehicular ad hoc network (VANET) for its practical deployment. The security of these techniques requires a common secret key to be shared between the communicating entities or depend upon the premise that some mathematical problems are computationally hard. However, because of the open nature of the wireless medium, the communication cannot be kept confidential and is prone to eavesdropping. Furthermore, with the arrival of quantum computers, these techniques are prone to quantum attacks—the time complexity of the assumed hard problem gets reduced from millions of years to a few seconds. In this paper, we propose a conditional privacy-preserving authentication scheme based on a quantum key distribution protocol for vehicle-to-infrastructure (V2I) communication. Our scheme inherits the properties of the quantum key distribution protocol. It does not require a secret authentication key to be transmitted conventionally and is resistant to quantum attacks. Apart from protecting VANETs against generic security threats, including node impersonation, message tampering, and repudiation, our scheme defends VANETs against man-in-the-middle attacks, replay attacks, etc. Besides, our protocol ensures message unlinkability, vehicle-identity privacy, and vehicle traceability if a vehicle misbehaves. The results obtained from the performance evaluation of our scheme confirm reasonable values of information leakage, key length, bit error probability, etc.
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).