Constantinos Patsakis

This work provides a systematic literature review of blockchain-based applications across multiple domains. The aim is to investigate the current state of blockchain technology and its applications and to highlight how specific characteristics of this disruptive technology can revolutionise “business-as-usual” practices. To this end, the theoretical underpinnings of numerous research papers published in high ranked scientific journals during the last decade, along with several reports from grey literature as a means of streamlining our assessment and capturing the continuously expanding blockchain domain, are included in this review. Based on a structured, systematic review and thematic content analysis of the discovered literature, we present a comprehensive classification of blockchain-enabled applications across diverse sectors such as supply chain, business, healthcare, IoT, privacy, and data management, and we establish key themes, trends and emerging areas for research. We also point to the shortcomings identified in the relevant literature, particularly limitations the blockchain technology presents and how these limitations spawn across different sectors and industries. Building on these findings, we identify various research gaps and future exploratory directions that are anticipated to be of significant value both for academics and practitioners.

The new era of mobile health ushered in by the wide adoption of ubiquitous computing and mobile communications has brought opportunities for governments and companies to rethink their concept of healthcare. Simultaneously, the worldwide urbanization process represents a formidable challenge and attracts attention toward cities that are expected to gather higher populations and provide citizens with services in an efficient and human manner. These two trends have led to the appearance of mobile health and smart cities. In this article we introduce the new concept of smart health, which is the context-aware complement of mobile health within smart cities. We provide an overview of the main fields of knowledge that are involved in the process of building this new concept. Additionally, we discuss the main challenges and opportunities that s-Health would imply and provide a common ground for further research.

Upon the General Data Protection Regulation's (GDPR) application on 25 May 2018 across the European Union, new legal requirements for the protection of personal data will be enforced for data controllers operating within the EU territory. While the principles encompassed by the GDPR were mostly welcomed, two of them, namely the right to withdraw consent and the right to be forgotten, caused prolonged controversy among privacy scholars, human rights advocates and business world due to their pivotal impact on the way personal data would be handled under the new legal provisions and the drastic consequences of enforcing these new requirements in the era of big data and internet of things. In this work, we firstly review all controversies around the new stringent definitions of consent revocation and the right to be forgotten in reference to their implementation impact on privacy and personal data protection, and secondly, we evaluate existing methods, architectures and state-of-the-art technologies in terms of fulfilling the technical practicalities for the implementation and effective integration of the new requirements into current computing infrastructures. The latter allow us to argue that such enforcement is indeed feasible provided that implementation guidelines and low-level business specifications are put in place in a clear and cross-platform manner in order to cater for all possible exceptions and complexities.

Recent advances in hardware and telecommunications have enabled the development of low cost mobile devices equipped with a variety of sensors. As a result, new functionalities, empowered by emerging mobile platforms, allow millions of applications to take advantage of vast amounts of data. Following this trend, mobile health applications collect users health-related information to help them better comprehend their health status and to promote their overall wellbeing. Nevertheless, health-related information is by nature and by law deemed sensitive and, therefore, its adequate protection is of substantial importance. In this paper we provide an in-depth security and privacy analysis of some of the most popular freeware mobile health applications. We have performed both static and dynamic analysis of selected mobile health applications, along with tailored testing of each application's functionalities. Long term analyses of the life cycle of the reviewed apps and our general data protection regulation compliance auditing procedure are unique features of the present paper. Our findings reveal that the majority of the analyzed applications do not follow well-known practices and guidelines, not even legal restrictions imposed by contemporary data protection regulations, thus jeopardizing the privacy of millions of users.

Despite common arguments about the prevalence of blockchain technology, in terms of security, privacy, and immutability, in reality, several attacks can be launched against them. This paper provides a systematic literature review on long-range attacks for proof of stake protocols. If successful, these attacks may take over the main chain and partially, or even completely, rewrite the history of transactions that are stored in the blockchain. To this end, we describe how proof of stake protocols work, their fundamental properties, their drawbacks, and their attack surface. After presenting long-range attacks, we discuss possible countermeasures and their applicability.