Blockchains, Volume 2, Issue 2 (June 2024) – 5 articles

The decentralized nature of blockchain enables data traceability, transparency, and immutability as complementary security features to the existing Internet of Things (IoT) systems. These Blockchain-based IoT (BIoT) systems aim to mitigate security risks such as malicious control, data leakage, and dishonesty often found in traditional cloud-based, vendor-specific IoT networks. As we steadily advance into the era of situation-aware IoT, the use of machine learning (ML) techniques has become essential for synthesizing situations based on sensory contexts. However, the challenge to integrate learning-based situation awareness with BIoT systems restricts the full potential of such integration. This is primarily due to the conflicts between the deterministic nature of smart contracts and the non-deterministic nature of machine learning, as well as the high costs of conducting machine learning on blockchain. To address the challenge, we propose a framework named Situ-Oracle. With the framework, a computation oracle of the blockchain ecosystem is leveraged to provide situation analysis as a service, based on Recurrent Neural Network (RNN)-based learning models tailored for the Situ model, and specifically designed smart contracts are deployed as intermediary communication channels between the IoT devices and the computation oracle. We used smart homes as a case study to demonstrate the framework design. Subsequently, system-wide evaluations were conducted over a physically constructed BIoT system. The results indicate that the proposed framework achieves better situation analysis accuracy (above 95%) and improves gas consumption as well as network throughput and latency when compared to baseline systems (on-chain learning or off-chain model verification). Overall, the paper presents a promising approach for improving situation analysis for BIoT systems, with potential applications in various domains such as smart homes, healthcare, and industrial automation. Full article

As blockchain becomes more widely used, a growing number of application fields are becoming interested in blockchain to benefit from its decentralised nature, invariability, security, transparency, quick transaction capabilities, and cost-effectiveness. Blockchain has a wide range of applications and uses in healthcare. Distributed ledger technology facilitates the secure transfer of patient medical records, manages the medicine supply chain, and creates an efficient, transparent, safe, and effective way of communicating data across global healthcare. The organ transplantation process (OTP) is one of the healthcare areas that benefit from the use of such technology to make its process more secure and transparent. In this article, we put forward a systematic literature review analysis on the application of blockchain to the OTP. Additionally, we address and highlight the barriers and challenges that arise while using blockchain technology for the OTP. We also offer some suggestions for future developments that would enhance blockchain’s implementation in the OTP domain. Full article

Practical Byzantine Fault Tolerance (PBFT) is the protocol of choice for many applications that require distributed consensus between a number of participant nodes. While PBFT assumes a single voting committee, many applications recognize different groups of participants that need to reach a consensus separately before accepting a proposal. To this end, we propose to count the votes by separate groups or committees of participating nodes, instead of all together as in the original PBFT. We then investigate the performance impact of this approach on the mean time to accept a data block and the number of nodes involved in making the final decision. Our results indicate that the proposed solutions impose a slight performance penalty which may be countermanded by reducing the quorum numbers needed in different subsets of the original committee. Full article

Blockchain technology is increasingly being recognized for its pivotal role in enhancing security, immutability, and transparency across government sectors, notably in land registration (LR) processes. This research emphasizes the need for contextually adapted blockchain technology solutions, particularly in resource-constrained and culturally diverse settings. Utilizing the elaborated action design research method, this study presents a Hyperledger-based blockchain technology system tailored for Sudan’s LR, addressing technical challenges, evaluation frameworks, privacy measures, and deployment strategies. This system not only facilitates secure and transparent land transactions from planning to certificate issuance, but also integrates the management of land sales, significantly reducing the need for intermediaries. By providing a detailed exploration of the system’s goals, technical hurdles, and practical deployment insights, this research contributes valuable knowledge to the implementation of blockchain technology in LR, with findings that are applicable to similar contexts globally. This study underscores the importance of customizing blockchain solutions to meet the unique requirements of different environments, thereby advancing digital government in resource-constrained settings. Full article

Many Blockchain-based approaches have been published in the field of health data management applications (HDMAs). However, no comprehensive guideline exists to guide the multiple and interdependent design decisions to develop such systems. This paper aims to support the HDMA system design processes by introducing a novel decision model. The model considers all relevant requirements, from regulatory context to user needs and trust considerations. To generate the decision model, we define a taxonomy that organizes previously published approaches by their technical design features and combines it with the trust assumptions of the participating actors according to the STRIDE method. The model aims to support a cohesive overall system design by addressing Blockchain type, off-chain storage, identity and access management, security decisions, and the specific use case of data donation. A group of experts evaluated the decision tree and its utility is demonstrated in three representative use cases. Special attention is paid to the use case of data donation via a data trustee, which is examined in detail. Full article