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Mobile users share the same expectations as wired users: they want to communicate with other people, they ex-pect the communication to be secure, and it should all be easy. However, mobility poses many challenges for security. Communication is often ad hoc, and the infras-tructure may be untrusted. Secure communication relies on the distribution of au-thentic information among the communicating parties’ devices. This is a challenging problem because devices generally do not share pre-existing secrets. Current secu-rity protocols for distributing initial authentic informa-tion fail to consider the human element. Many protocols do not scale beyond a pair of devices, although people often need to communicate with a group. The few exist-ing group protocols assume that users will always count the number of members and verify the list of members correctly. However, as group size increases, implemen-tations of these protocols become more prone to human error. We present GAnGS, a fully-implemented system for exchanging authentic information between mobile de-vices when they are physically present in the same lo-cation. GAnGS is scalable, appropriate for two or more devices. We implement two user-friendly variants of GAnGS on Nokia N70 camera phones. The first vari-ant, GAnGS-P, is based on an untrusted communication hub. The second variant, GAnGS-T, needs no infrastruc-ture. Both variants use Bluetooth for peer-to-peer wire-less communication during the information exchange. 1

the work on various conferences, for which I thank him. I would also like to thank Prof. Dr. Roger Wattenhofer, responsible for the Koreferat of this work. Also, Prof. Dr. Oscar Nierstrasz who was willing to be the co-examinator of this work deserves many thanks. Many thanks go to my colleagues of the RVS

A particularly important sector for the stability of financial systems is the banking sector. Banks play a central role in the money creation process and in the payment system. Moreover, bank credit is an important factor in the financing of investment and growth. Faltering banking systems have

of the signal complexity. In practice, this enables lower sampling rates that can be more easily achieved by current hardware designs. The primary bottleneck that limits ADC sam-pling rates is quantization, i.e., higher bit-depths impose lower sampling rates. Thus, the decreased sampling rates of CS ADCs

April 29, 2011Für UnsShe had never before seen a rabbit with either a waistcoat-pocket, or a watch to take out of it, and burning with curiosity, she ran across the field after it Lewis CarrollThe following document, written under the supervision of Dr. reviewed by:

ACKNOWLEDGMENTS I would like to give many thanks to Dr. Shengli Fu and Dr. Yan Huang as my advi-

ii iii CHRISTOPHER CHARLES WEIGLE: Displays for Exploration and Comparison of Nested

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An approach based on Extreme Value Theory as a measure to quantify market risk of equity securities and portfolios