In recent years, traceability systems have been developed as practical tools for improving supply chain (SC) transparency and visibility, especially in health and safety-sensitive sectors like food and pharmaceuticals. Blockchain-related SC traceability research has received significant attention during the last several years, and arguably blockchain is currently the most promising technology for providing traceability-related services in SC networks. This paper provides a systematic literature review of the various technical implementation aspects of blockchain-enabled SC traceability systems. We apply different drivers for classifying the selected literature, such as (a) the various domains of the available blockchain-enabled SC traceability systems and relevant methodologies applied; (b) the implementation maturity of these traceability systems along with technical implementation details; and (c) the sustainability perspective (economic, environmental, social) prevalent to these implementations. We provide key takeaways regarding the open issues and challenges of current blockchain traceability implementations and fruitful future research areas. Despite the significant volume and plethora of blockchain-enabled SC traceability systems, academia has so far focused on unstructured experimentation of blockchain-associated SC traceability solutions, and there is a clear need for developing and testing real-life traceability solutions, especially taking into account feasibility and cost-related SC aspects.

The Internet of Medical Things (IoMT) couples IoT technologies with healthcare services in order to support real-time, remote patient monitoring and treatment. However, the interconnectivity of critical medical devices with other systems in various network layers creates new opportunities for remote adversaries. Since most of the communication protocols have not been specifically designed for the needs of connected medical devices, there is a need to classify the available IoT communication technologies in terms of security. In this paper we classify IoT communication protocols, with respect to their application in IoMT. Then we describe the main characteristics of IoT communication protocols used at the perception, network and application layer of medical devices. We examine the inherent security characteristics and limitations of IoMT-specific communication protocols. Based on realistic attacks we identify available mitigation controls that may be applied to secure IoMT communications, as well as existing research and implementation gaps.

The health care ecosystem involves various interconnected stakeholders with different, and sometimes conflicting security and privacy needs. Sharing medical data, sometimes generated by remote medical devices, is a challenging task. Although several solutions exist in the literature covering functional requirements such as interoperability and scalability, as well as security & privacy requirements such as fine-grained access control and data privacy, balancing between them is not a trivial task as off-the-shelf solutions do not exist. On one hand, centralized cloud architectures provide scalability and interoperable access, but make strong trust assumptions. On the other, decentralized blockchain based solutions favor data privacy and independent trust management, but typically do not support dynamic changes of the underlying trust domains. To cover this gap, in this paper, we present a novel hierarchical multi expressive blockchain architecture. At the top layer, a proxy blockchain enables independently managed trust authorities to interoperate. End-users from different health care domains, such as hospitals or device manufacturers are able to access and securely exchange medical data, provided that a commonly agreed domain-wise access policy is enforced. At the bottom layer, one or more domain blockchains allow each domain (e.g. a hospital or device manufacturer) to enforce their policy and allow fine-grained access control with attribute-based encryption. This architecture is designed to provide the autonomous management of trusted medical data/devices and the transactions of mutually untrusted stakeholders, as well as an inherent forensics mechanism tailored for granular auditing. Smart contracts are used to enforce decentralized policies. Ciphertext-policy attribute based encryption (CP-ABE) is used to distribute the decryption process among end users and the system, as well as support an efficient credential revocation mechanism. We demonstrate the efficiency of the proposed architecture through a proof of concept implementation. Finally we analyse the major security and performance characteristics.