Proactive Antifragility: A New Paradigm for NextGeneration Cyber Defence at the Edge Recent advances in the Internet of Things (IoT) and, more generally, distributed computing research have given rise to various edgeoriented computing paradigms including Edge, Fog, and Mobile CloudComputing. Systems adhering to these paradigms exhibit a number of characteristics such as high levels of heterogeneity and dynamicity, leading to high complexity, that exacerbate the problems associated with traditional cyber defence. These problems are further exacerbated when edgeoriented systems operate in adversarial environments, e.g. the Internet of Battle Things (IoBT). Current generations of cyber defence approaches straddling attack prevention, detection, response and tolerance are arguably insufficient for edgeoriented systems operating in IoBT environments, especially given the constant increase in cyber attack sophistication. In this paper, we propose proactive antifragility as a new paradigm for the next generation of cyber defence approaches capable of taking into account the aforementioned system characteristics and environmental challenges. We propose a conceptualization of proactive antifragility, and then outline associated challenges and research directions indicating which existing approaches can be reused or advanceddeveloped further in order for proactive antifragility to be achieved at the edge.

Towards a Threat Model for Fog Computing In recent years, the addition of billions of Internet of Thing (IoT) device spawned a massive demand for computing service near the edge of the network. Due to latency, limited mobility, and location awareness, cloud computing is not capable enough to serve these devices. As a result, the focus is shifting more towards distributed platform service to put ample computing power near the edge of the networks. Thus, paradigms such as Fog and Edge computing are gaining attention from researchers as well as business stakeholders. Fog computing is a new computing paradigm, which places computing nodes in between the Cloud and the end user to reduce latency and increase availability. As an emerging technology, Fog computing also brings newer security challenges for the stakeholders to solve. Before designing the security models for Fog computing, it is better to understand the existing threats to Fog computing. In this regard, a thorough threat model can significantly help to identify these threats. Threat modeling is a sophisticated engineering process by which a computerbased system is analyzed to discover security flaws. In this paper, we applied two popular security threat modeling processes  CIAA and STRIDE  to identify and analyze attackers, their capabilities and motivations, and a list of potential threats in the context of Fog computing. We posit that such a systematic and thorough discussion of a threat model for Fog computing will help security researchers and professionals to design secure and reliable Fog computing systems.