A Few Research Outputs

The following are some example research outputs from the research labs.

Blockchain Lab, University of Edinburgh

Ouroboros: A provably secure proof-of-stake blockchain protocol

Kiayias, A., Russell, A., David, B., & Oliynykov, R. (2017, July). Ouroboros: A provably secure proof-of-stake blockchain protocol. In Annual international cryptology conference (pp. 357-388). Cham: Springer International Publishing.

We present “Ouroboros”, the first blockchain protocol based on proof of stake with rigorous security guarantees. We establish security properties for the protocol comparable to those achieved by the bitcoin blockchain protocol. As the protocol provides a “proof of stake” blockchain discipline, it offers qualitative efficiency advantages over blockchains based on proof of physical resources (e.g., proof of work). We also present a novel reward mechanism for incentivizing Proof of Stake protocols and we prove that, given this mechanism, honest behavior is an approximate Nash equilibrium, thus neutralizing attacks such as selfish mining.

The bitcoin backbone protocol: Analysis and applications

Garay, J., Kiayias, A., & Leonardos, N. (2024). The bitcoin backbone protocol: Analysis and applications. Journal of the ACM, 71(4), 1-49.

Bitcoin is the first and most popular decentralized cryptocurrency to date. In this work, we extract and analyze the core of the Bitcoin protocol, which we term the Bitcoin backbone, and prove three of its fundamental properties which we call Common Prefix, Chain Quality, and Chain Growth in the static setting where the number of players remains fixed. Our proofs hinge on appropriate and novel assumptions on the “hashing power” of the protocol participants and their interplay with the protocol parameters and the time needed for reliable message passing between honest parties in terms of computational steps. A takeaway from our analysis is that, all else being equal, the protocol’s provable tolerance in terms of the number of adversarial parties (or, equivalently, their “hashing power” in our model) decreases as the duration of a message passing round increases.

Ouroboros praos: An adaptively-secure, semi-synchronous proof-of-stake blockchain

David, B., Gaži, P., Kiayias, A., & Russell, A. (2018). Ouroboros praos: An adaptively-secure, semi-synchronous proof-of-stake blockchain. In Advances in Cryptology–EUROCRYPT 2018: 37th Annual International Conference on the Theory and Applications of Cryptographic Techniques, Tel Aviv, Israel, April 29-May 3, 2018 Proceedings, Part II 37 (pp. 66-98). Springer International Publishing

We present “Ouroboros Praos”, a proof-of-stake blockchain protocol that, for the first time, provides security against fully-adaptive corruption in the semi-synchronous setting: Specifically, the adversary can corrupt any participant of a dynamically evolving population of stakeholders at any moment as long the stakeholder distribution maintains an honest majority of stake; furthermore, the protocol tolerates an adversarially-controlled message delivery delay unknown to protocol participants.

Blockpass ID Lab, Edinburgh Napier University

LEAGAN: A Decentralized Version-Control Framework for Upgradeable Smart ContractsYour Attractive Heading

Kumar, G., Saha, R., Conti, M., & Buchanan, W. J. (2025). LEAGAN: A Decentralized Version-Control Framework for Upgradeable Smart Contracts. IEEE Transactions on Services Computing, (99), 1-15.

Smart contracts are integral to decentralized systems like blockchains and enable the automation of processes through programmable conditions. However, their immutability, once deployed, poses challenges when addressing errors or bugs. Existing solutions, such as proxy contracts, facilitate upgrades while preserving application integrity. Yet, proxy contracts bring issues such as storage constraints and proxy selector clashes – along with complex inheritance management. This paper introduces a novel upgradeable smart contract framework with version control, named ”decentraLized vErsion control and updAte manaGement in upgrAdeable smart coNtracts (LEAGAN).” LEAGAN is the first decentralized updatable smart contract framework that employs data separation with Incremental Hash (IH) and Revision Control System (RCS).

Chaotic quantum encryption to secure image data in post quantum consumer technology

Khan, M. S., Ahmad, J., Al-Dubai, A., Pitropakis, N., Ghaleb, B., Ullah, A., … & Buchanan, W. J. (2024). Chaotic quantum encryption to secure image data in post quantum consumer technology. IEEE Transactions on Consumer Electronics.

The rapid advancement in consumer technology has led to an exponential increase in the connected devices, resulting in an enormous and continuous flow of data, particularly the image data. This data needs to be processed, managed, and secured efficiently, especially in the quantum-enabled consumer technology era. This paper, in this regards, presents a quantum image encryption scheme featuring a novel two-phase chaotic confusion-diffusion architecture. The proposed architecture consists of four distinct confusion-diffusion modules that perform a simultaneous qubit and pixel-level encryption on both the position and intensity of quantum encoded pixels. Moreover, quantum circuits for qubit-level chaotic transformation and chaos-based selective perfect shuffle operation have been implemented, which collectively enhance the encryption strength of the proposed scheme.

Application of Randomness for Security and Privacy in Multi-Party Computation

Saha, R., Kumar, G., Geetha, G., Conti, M., & Buchanan, W. J. (2024). Application of Randomness for Security and Privacy in Multi-Party Computation. IEEE Transactions on Dependable and Secure Computing.

A secure Multi-Party Computation (MPC) is one of the distributed computational methods, where it computes a function over the inputs given by more than one party jointly and keeps those inputs private from the parties involved in the process. Randomization in secret sharing leading to MPC is a requirement for privacy enhancements; however, most of the available MPC models use the trust assumptions of sharing and combining values. Thus, randomization in secret sharing and MPC modules is neglected. As a result, the available MPC models are prone to information leakage problems, where the models can reveal the partial values of the sharing secrets. In this paper, we propose the first model of utilizing a random function generator as an MPC primitive.

Trustworthy Connected Systems Lab, University of Glasgow

A Scalable Multi-layer PBFT Consensus for Blockchain

Li, W., Feng, C., Zhang, L., Xu, H., Cao, B., & Imran, M. A. (2020). A scalable multi-layer PBFT consensus for blockchain. IEEE Transactions on Parallel and Distributed Systems, 32(5), 1146-1160.

Practical Byzantine Fault Tolerance (PBFT) consensus mechanism shows a great potential to break the performance bottleneck of the Proof-of-Work (PoW)-based blockchain systems, which typically support only dozens of transactions per second and require minutes to hours for transaction confirmation. However, due to frequent inter-node communications, PBFT mechanism has a poor node scalability and thus it is typically adopted in small networks. To enable PBFT in large systems such as massive Internet of Things (IoT) ecosystems and blockchain, in this article, a scalable multi-layer PBFT-based consensus mechanism is proposed by hierarchically grouping nodes into different layers and limiting the communication within the group. We first propose an optimal double-layer PBFT and show that the communication complexity is significantly reduced.

When Internet of Things Meets Blockchain: Challenges in Distributed Consensus

Cao, B., Li, Y., Zhang, L., Zhang, L., Mumtaz, S., Zhou, Z., & Peng, M. (2019). When Internet of Things meets blockchain: Challenges in distributed consensus. Ieee Network, 33(6), 133-139.

Blockchain has been regarded as a promising technology for IoT, since it provides significant solutions for decentralized networks that can address trust and security concerns, high maintenance cost problems, and so on. The decentralization provided by blockchain can be largely attributed to the use of a consensus mechanism, which enables peer-to-peer trading in a distributed manner without the involvement of any third party. This article starts by introducing the basic concept of blockchain and illustrating why a consensus mechanism plays an indispensable role in a blockchain enabled IoT system. Then we discuss the main ideas of two famous consensus mechanisms, PoW and PoS, and list their limitations in IoT. Next, two mainstream DAG based consensus mechanisms, the Tangle and Hashgraph, are reviewed to show why DAG consensus is more suitable for IoT system than PoW and PoS.

Wireless distributed consensus in vehicle to vehicle networks for autonomous driving

Feng, C., Xu, Z., Zhu, X., Klaine, P. V., & Zhang, L. (2023). Wireless distributed consensus in vehicle to vehicle networks for autonomous driving. IEEE Transactions on Vehicular Technology, 72(6), 8061-8073.

Vital societal and industrial autonomous components are increasingly interconnected through communication networks to complete critical tasks cooperatively. However, as the reliability and trust requirements for connected autonomous systems continue to grow, the centralized communication and decision approaches that are in use today are reaching their limits. Focusing on autonomous driving applications, this paper proposes a resilient and trustworthy framework on wireless distributed consensus networks, where the communication links are less reliable or are even in the presence of incorrect local sensor readings/decisions. To accomplish that, a novel three stages consensus mechanism is proposed based on the practical Byzantine fault tolerance (PBFT), where the veto collection and gossip stages are designed to meet the stringent and complex requirements for a vehicle’s maneuvers. A plan tree synthesis is also proposed to make consensus on a series of decisions while adopting network members’ decision preferences. A detailed protocol including the distributed consensus, plan tree synthesis, dynamic grouping, etc. is proposed. Simulation results show that the proposed consensus mechanism is able to be reached and propagated through the network under poor wireless communication conditions and the presence of faulty vehicles with incorrect sensor readings.