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Vibration-base key exchange among multiple smart devices on the desk

Arno A., Toyoda K., Watanabe Y., Sasase I., Mathiopoulos P. T.

Image Processing & Communications

2016

Vol. 21, no. 2

33--42

Eavesdropping is a real concern in mobile NFC (Near Filed Communication) pay- ment and data sharing applications. Although DH (Diffie-Hellman) scheme has been widely used in key exchange for secure communica- tions, it may fail in an indoor environment due to the vulnerability against man-in-the-middle attack. In this paper, we propose a vibration- based key exchange among multiple smart de- vices on the desk. In our scheme, devices are assumed to be placed next to each other and each device vibrates with patterns converted from a key to be exchanged and measures them with accelerometer to recover it. Then, each key is recovered from measured acceleration. We implement our scheme with Android smart- phones to show the effectiveness of the pro- posed scheme.

Log-MAP Decoding of Turbo Codes and Turbo Trellis-Codec Modulation Using Piecewise-Linear Approximations of the max* Operator

Sybis M., Tyczka P., Papaharalabos S., Mathiopoulos P. T., Masera G., Martina M.

Electronics and Telecommunications Quarterly

2009

Vol. 55, No 3

435-451

A novel approach for approximating the max* operator, used in the Log-MAP decoding algorithm, is presented. In this approximation it is not necessary to use any additional correction term, as previous approximation methods require. Several decoding algorithms are obtained for both turbo and turbo trellis-coded modulation (TTCM) codes with optimal and near-optimal bit error rate (BER) performance depending on a single parameter, namely the number of piecewise-linear (PWL) approximation terms used. The decoding complexity is estimated, showing the practical implementation advantages of the proposed method against the Log-MAP algorithm.