Software Defined Networking (SDN) is rapidly emerging as a new paradigm for managing and controlling the operation of networks ranging from the data center to the core, enterprise, and home. The logical centralization of network intelligence presents exciting challenges and opportunities to enhance security in such networks, including new ways to prevent, detect, and react to threats, as well as innovative security services and applications that are built upon SDN capabilities. In this paper, we undertake a comprehensive survey of recent works that apply SDN to security, and identify promising future directions that can be addressed by such research.

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Wearable wireless sensor devices are key components in the emerging technology of personalized healthcare monitoring. Medical data collected by these devices must be secured, especially on the wireless link to the gateway equipment. However, it is difficult to manage the required cryptographic keys, as users may lack the awareness or requisite skills for this task. Alternatively, recent work has shown that two communicating devices can generate secret keys derived directly from symmetrical properties of the wireless channel between them. This channel is also strongly dependent on positioning and movement and cannot be inferred in detail by an eavesdropper. Existing schemes, however, yield keys with mismatching bits at the two ends, requiring reconciliation mechanisms with high implementation and energy costs that are unsuitable for resource-poor body-worn devices.In this work we propose a secret-key generation mechanism which uses signal strength fluctuations caused by incidental motion of body-worn devices to construct shared keys with near-perfect agreement, thereby avoiding reconciliation costs. Our contributions are: (1) we analyse channel measurement asymmetries caused by non-simultaneous probing of the channel by the link end-points, (2) we propose a practical filtering scheme to minimize these asymmetries, dramatically improving signal correlation between the two ends without reducing entropy, and (3) we develop a method to restrict key generation to periods of channel fluctuation, ensuring near-perfect key agreement. To the best of our knowledge, this work is the first to demonstrate the feasibility of generating high quality secret keys with zero reconciliation cost in body-worn networks for healthcare monitoring.

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Abstract-In this paper, we investigate the feasibility of realtime derivation of cryptographic keys in body area networks using unique characteristics of the underlying wireless channel. We perform experiments to confirm that motion does indeed provide significant highly correlated randomness on either end of the wireless link between basestation and mobile mote to enable real-time key generation. Furthermore, we demonstrate that channel characteristics for a dynamic body area network consist of two different components, a fast and a slow component, each of which make a qualitatively different contribution to key generation. These components can be isolated to address specific needs of the application scenario: the fast component can yield high entropy keys at a fast rate between basestation and mobile mote with some bit disagreement between the two devices; the slow component generates keys at a lower rate but with very high level of bit agreement. Our experimental results highlight this tradeoff, and our key generation protocol details the key extraction process.