Date of Award

9-16-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Computer Science

First Advisor

Shucheng Yu

Abstract

In wireless wearable system such as body area network (BAN), device authentication and secret key extraction are essential for trustworthy and reliable gathering and delivery of user’s critical health information. Traditional authentication solutions depend on prior trust among nodes whose establishment would require either key pre-distribution or non-intuitive participation by inexperienced users. Most existing non-cryptographic authentication schemes require advanced hardware or significant modifications to the system software, which are impractical for BANs. Recently, most wireless network security schemes merely based on physical layer characteristics tackle device authentication and secret key extraction, but separately. It remains an open problem to simultaneously achieve device authentication and fast secret key extraction merely using wireless physical layer characteristics, without the help of advanced hardware or out-of-band channel. In the dissertation, I propose several security schemes exploiting physical layer characteristics naturally arising from the multi-path wireless environment, which do not depend on prior-trust among nodes, advanced hardware and out-of-band channels. First, I introduce BANA, a lightweight authentication in BAN, which utilizes the distinct received signal strength (RSS) variations among on-body and off-body channels. Clustering is adopted to differentiate the signals from an attacker and a legitimate node. Furthermore, to perform device authentication and fast secret key extraction at the same time, we propose MASK-BAN, a lightweight fast authenticated secret key extraction scheme for intra-BAN communication. Based on RSS measurements, MASK-BAN achieves authentication through multi-hop stable channels and key extraction through dynamic channels. Especially, key extraction between two on-body devices with multi-hop relay nodes is modeled as a max-flow problem, and a novel collaborative secret key generation algorithm is introduced to maximize the key generation rate. Besides, channel state information (CSI), also measured from PHY-layer of wireless channels, is exploited to facilitate device authentication in Wi-Fi environments. Effectiveness and efficiency of the proposed schemes are validated by simulations and experiments on real sensor platforms under various scenarios.

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