Abstract
The growing demand for everyday data insights drives the pursuit of more sophisticated infrastructures and artificial intelligence algorithms. When combined with the growing number of interconnected devices, this originates concerns about scalability and privacy. The main problem is that devices can detect the environment and generate large volumes of possibly identifiable data. Public cloud-based technologies have been proposed as a solution, due to their high availability and low entry costs. However, there are growing concerns regarding data privacy, especially with the introduction of the new General Data Protection Regulation, due to the inherent lack of control caused by using off-premise computational resources on which public cloud belongs. Users have no control over the data uploaded to such services as the cloud, which increases the uncontrolled distribution of information to third parties. This work aims to provide a modular approach that uses cloud-of-clouds to store persistent data and reduce upfront costs while allowing information to remain private and under users' control. In addition to storage, this work also extends focus on usability modules that enable data sharing. Any user can securely share and analyze/compute the uploaded data using private computing without revealing private data. This private computation can be training machine learning (ML) models. To achieve this, we use a combination of state-of-the-art technologies, such as MultiParty Computation (MPC) and K-anonymization to produce a complete system with intrinsic privacy properties.

Abstract
The increasing pervasiveness of the Internet of Things is resulting in a steady increase of cyberattacks in all of its facets. One of the most predominant attack vectors is related to its identity management, as it grants the ability to impersonate and circumvent current trust mechanisms. Given that identity is paramount to every security mechanism, such as authentication and access control, any vulnerable identity management mechanism undermines any attempt to build secure systems. While digital certificates are one of the most prevalent ways to establish identity and perform authentication, their provision at scale remains open. This provisioning process is usually an arduous task that encompasses device configuration, including identity and key provisioning. Human configuration errors are often the source of many security and privacy issues, so this task should be semi-autonomous to minimize erroneous configurations during this process. In this paper, we propose an identity management (IdM) and authentication method called YubiAuthIoT. The overall provisioning has an average runtime of 1137.8 ms +/- 65.11+delta. We integrate this method with the FIWARE platform, as a way to provision and authenticate IoT devices.

Abstract
Byzantine fault tolerant (BFT) protocols are designed to increase system dependability and security. They guarantee liveness and correctness even in the presence of arbitrary faults. However, testing and validating BFT systems is not an easy task. As is the case for most concurrent and distributed applications, the correctness of these systems is not solely dependant on algorithm and protocol correctness. Ensuring the correct behaviour of BFT systems requires exhaustive testing under real-world scenarios. An approach is to use fault injection tools that deliberate introduce faults into a target system to observe its behaviour. However, existing tools tend to be designed for specific applications and systems, thus cannot be used generically. We argue that more advanced and powerful tools and frameworks are needed for testing the security and safety of distributed applications in general, and BFT systems in particular. Specifically, a fault injection framework that can be integrated into both client and server side applications, for testing them exhaustively. We present ZERMIA, a modular and extensible fault injection framework, designed for testing and validating concurrent and distributed applications. We validate ZERMIA’s principles by conduction a series of experiments on a distributed applications and a state of the art BFT library, to show the benefits of ZERMIA for testing and validating applications. © 2021, Springer Nature Switzerland AG.

Abstract
With the rising popularity of the cloud, companies lose control of both the hardware and the operating system responsible for hosting their software and data. This means that companies are at risk of losing confidential data when these are utilized in components controlled by a third-party cloud vendor. Secure enclaves can help solve this problem by creating a secure environment where code can be executed securely, guaranteeing that no unwanted parties read or modify the data inside this secure environment. While the use of secure enclaves has been focused on small footprints software, such as the implementation of trusted computing base for distributed protocols, we analyze the strengths and shortcoming of current tools in an effort to further expand the applicability of their use. Given the importance of web servers and their inherent greater exposure to attacks, we explore the hardening of Apache web server through the use of secure enclaves. This was accomplished by making the necessary modifications to further protect its private key from both the operating system and hypervisor. We also provide a performance assessment to quantify the overhead associated with the use of secure enclaves, namely, Intel SGX.

Abstract
Purpose The aim of this paper is to evaluate the use of blockchain for identity management (IdM) in the context of the Internet of things (IoT) while focusing on privacy-preserving approaches and its applications to healthcare scenarios. Design/methodology/approach The paper describes the most relevant IdM systems focusing on privacy preserving with or without blockchain and evaluates them against ten selected features grouped into three categories: privacy, usability and IoT. Then, it is important to analyze whether blockchain should be used in all scenarios, according to the importance of each feature for different use cases. Findings Based on analysis of existing systems, Sovrin is the IdM system that covers more features and is based on blockchain. For each of the evaluated use cases, Sovrin and UniquID were the chosen systems. Research limitations/implications This paper opens new lines of research for IdM systems in IoT, including challenges related to device identity definition, privacy preserving and new security mechanisms. Originality/value This paper contributes to the ongoing research in IdM systems for IoT. The adequacy of blockchain is not only analyzed considering the technology; instead the authors analyze its application to real environments considering the required features for each use case.

Abstract
Byzantine Fault tolerant (BFT) protocols are implemented to guarantee the correct system/application behavior even in the presence of arbitrary faults (i.e., Byzantine faults). Byzantine Fault tolerant State Machine Replication (BFT-SMR) is a known software solution for masking arbitrary faults and malicious attacks (Liu et al., 2020). In this survey, we present and discuss relevant BFT-SMR protocols, focusing on deterministic and probabilistic approaches. The main purpose of this paper is to discuss the characteristics of proposed works for each approach, as well as identify the trade-offs for each different approach.& COPY; 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )