José D. P. Rolim

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Collecting sensory data using a mobile data sink has been shown to drastically reduce energy consumption at the cost of increasing delivery delay. Towards improved energy-latency trade-offs, we propose a biased, adaptive sink mobility scheme, that adjusts to local network conditions, such as the surrounding density, remaining energy and the number of past(More)
Summary form only given. We study the problem of energy-balanced data propagation in wireless sensor networks. The energy balance property guarantees that the average per sensor energy dissipation is the same for all sensors, during the entire execution of the protocol. This property is important since it prolongs the network's lifetime by avoiding early(More)
In this paper we study and compare the performance of FPGA-based implementations of the ve nal AES candidates (MARS, RC6, Rijndael, Serpent, and Two sh). FPGAs seem to match extremely well with the operations required by the nal candidates. Among the various time-space implementation tradeo s, we focused primarily on time performance. The time performance(More)
Architectures that implement the Internet Protocol Security (IPSec) standard have to meet the enormous computing demands of cryptographic algorithms. In addition, IPSec architectures have to be flexible enough to adapt to diverse security parameters. This paper proposes an FPGAbased Adaptive Cryptographic Engine (ACE) for IPSec architectures. By taking(More)
We show that <italic>quick hitting set generators</italic> can replace <italic>quick pseudorandom generators</italic> to derandomize any probabilistic <italic>two-sided error</italic> algorithms. Up to now <italic>quick hitting set generators</italic> have been known as the general and uniform derandomization method for probabilistic <italic>one-sided(More)
We propose an algorithm to compute the optimal parameters of a probabilistic data propagation algorithm for wireless sensor networks (WSN). The probabilistic data propagation algorithm we consider was introduced in previous work, and it is known that this algorithm, when used with adequate parameters, balances the energy consumption and increases the(More)
We show how to simulate any BPP algorithm in polynomial time by using a weak random source of r bits and min-entropy r for any γ > 0. This follows from a more general result about sampling with weak random sources. Our result matches an information-theoretic lower bound and solves a question that has been open for some years. The previous best results were(More)