With sensitive data being increasingly stored on mobile devices and laptops, hard disk encryption is more important than ever. In particular, being able to plausibly deny that a hard disk contains certain information is a very useful and interesting research goal. However, it has been known for some time that existing "hidden volume" solutions, like TrueCrypt, fail in the face of an adversary who is able to observe the contents of a disk on multiple, separate occasions. In this work, we explore more robust constructions for hidden volumes and present HIVE, which is resistant to more powerful adversaries with multiple-snapshot capabilities. In pursuit of this, we propose the first security definitions for hidden volumes, and prove HIVE secure under these definitions. At the core of HIVE, we design a new write-only Oblivious RAM. We show that, when only hiding writes, it is possible to achieve ORAM with optimal O(1) communication complexity and only poly-logarithmic user memory. This is a significant improvement over existing work and an independently interesting result. We go on to show that our writeonly ORAM is specially equipped to provide hidden volume functionality with low overhead and significantly increased security. Finally, we implement HIVE as a Linux kernel block device to show both its practicality and usefulness on existing platforms.

In this paper we investigate the resiliency to jamming of data protocols, such as IP, over WLAN. We show that, on existing WLAN, an adversary can successfully jam data packets at a very low energy cost. Such attacks allow a set of adversary nodes disseminated over an area to prevent communication, partition an ad hoc network, or force packets to be routed over adversary chosen paths. The ratio of the jamming pulses duration to the transmission duration can be as low as 10--4. We investigate and analyze the performance of using various coding schemes to improve the robustness of wireless LANs for IP packets transmission. A concatenated code that is simple to decode and can maintain a low Frame Error Rate (FER) under a jamming effort ratio of 15%. We argue that LDPC codes will be very suitable to prevent this type of jamming. We investigate the theoretical limits by analyzing the performance derived from upper bounds on binary error-control codes. We also propose an efficient anti-jamming technique for IEEE802.11b.

We introduce a notion of universality in the context of optimization problems with partial information. Universality is a framework for dealing with uncertainty by guaranteeing a certain quality of goodness for all possible completions of the partial information set. Universal variants of optimization problems can be defined that are both natural and well-motivated. We consider universal versions of three classical problems: TSP, Steiner Tree and Set Cover.We present a polynomial-time algorithm to find a universal tour on a given metric space over

In this paper, we investigate the resiliency to jamming of data protocols, such as IP, over WLAN. We show that, on existing WLAN, an adversary can successfully jam data packets at a very low energy cost. Such attacks allow a set of adversary nodes disseminated over an area to prevent communication, partition an ad hoc network or force packets to be routed over adversary chosen paths. The ratio of the jamming pulses duration to the transmission duration can be as low as 10−4. We investigate and analyze the performance of combining a cryptographic interleaver with various coding schemes to improve the robustness of wireless LANs for IP packets transmission 1. A concatenated code that is simple to decode and can maintain a low frame error rate (FER) under a jamming effort ratio of 15%. We argue that LDPC codes will be very suitable to prevent this type of jamming. We investigate the theoretical limits by analyzing the performance derived from upper bounds on binary error‐control codes. We also propose an efficient anti‐jamming technique for IEEE802.11b based on Reed–Solomon codes. Copyright © 2004 John Wiley & Sons, Ltd.

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