Scenarios for securing content delivery in the DRM environment

In the DRM environment, content is usually distributed in an encrypted form. Typically,a secure encryption algorithm is utilized to accomplish such protection. However, executing this algorithm in an insecure environment may allow adversaries to compromise the system andobtain information about the decryption key. Keeping such a key secret is a major challenge for content distribution systems. We consider two solutions for securing content delivery. Thefirst solution involves modifying the algorithm in such a way as to make implementation unintelligible.The second solution involves setting a buyer-seller protocol to communicate the key securely. In addition, the protocol can be set to achieve security for the content provider and privacy protection for user. This paper describes a study of these scenarios for DRM applications w.r.t securing content delivery

White-box implementation to advantage DRM

Digital Rights Management (DRM) is a popular approach for secure content distribution. Typically, DRM encrypts the content before delivers it. Most DRM applications use secure algorithms to protect content. However, executing these algorithms in an insecure environment may allow adversaries to compromise the system and obtain the key. To withstand such attack, algorithm implementation is modified in such a way to make the implementation unintelligible, namely obfuscation approach. White-box cryptography (WBC) is an obfuscation technique intended to protect secret keys from being disclosed in a software implementation using a fully transparent methodology. This mechanism is appropriate for DRM applications and able to enhance security for the content provider. However, DRM is required to provide a balanced protection for the content provider and users. We construct a protocol on implementing WBC to improve DRM system. The system does not only provide security for the content provider but also preserves privacy for users

Fast Arithmetics Using Chinese Remaindering

In this paper, some issues concerning the Chinese remaindering representation are discussed. Some new converting methods, including an efficient probabilistic algorithm based on a recent result of von zur Gathen and Shparlinski \cite{Gathen-Shparlinski}, are described. An efficient refinement of the NC$^1$ division algorithm of Chiu, Davida and Litow \cite{Chiu-Davida-Litow} is given, where the number of moduli is reduced by a factor of $\log n$

Population and Environmental Correlates of Maize Yields in Mesoamerica: a Test of Boserup’s Hypothesis in the Milpa

Using a sample of 40 sources reporting milpa and mucuna-intercropped maize yields in Mesoamerica, we test Boserup’s (1965) prediction that fallow is reduced as a result of growing population density. We further examine direct and indirect effects of population density on yield. We find only mixed support for Boserupian intensification. Fallow periods decrease slightly with increasing population density in this sample, but the relationship is weak. Controlling for other covariates, fallow-unadjusted maize yields first rise then fall with population density. Fallow-adjusted maize yields peak at 390 kg/ha/yr for low population densities (8 persons / km2) and decline to around 280 kg/ha/yr for the highest population densities observed in our dataset. Fallow practices do not appear to mediate the relationship between population density and yield. The multi-level modeling methods we adopt allow for data clustering, accurate estimates of group-level variation, and they generate conditional predictions, all features essential to the comparative study of prehistoric and contemporary agricultural yields

NP is contained in DTIME(n^O(log^{gamma}))

We use existential Diophantine predicates carefully reinterpreted over the reals and the time complexity of Tarski algebra to show that 3-CNF SAT is in n^O(log^{gamma} n) time for an absolute positive constant gamma.Comment: This paper has been withdrawn due to a fatal flaw in the proof of Lemma

Computing a context-free grammar-generating series

The parallel complexity of computingcontext-freegrammargeneratingseries is investigated. It is known that this problem is in DIV, but in terms of nσ rather than n, where n is the index of the desired coefficient and σ is the grammar size. A new method is presented which is in DIV in terms of 22O(σ)·n. Evidence is provided that any direct application of elimination theory to this problem leads to a space and time resource factor that is nearly exponential in grammar size

Census algorithms for chinese remainder pseudorank

We investigate the density and distribution behaviors of the chinese remainder representation pseudorank. We give a very strong approximation to density, and derive two efficient algorithms to carry out an exact count (census) of the bad pseudorank integers. One of these algorithms has been implemented, giving results in excellent agreement with our density analysis out to 5189-bit integers

Additive Cellular Automata and Algebraic Series

Introduction A cellular automaton is a grid of elementary automata, each communicating only with a finite number of its neighbours. In the simplest models each elementary device, a cell or site, can take only two values and is updated at intervals according to a rule which expresses the actual value from its preceding value and that of its neighbours. Here the values are elements of a field K, finite or infinite. As O. Martin, A. Odlyzko and S. Wolfram [7] emphasized, the behaviour of a cellular automaton with a finite number of cells on a finite field is ultimately periodic. It is natural to consider also automata with cells in a line, which we call one dimensional automata. So a cell is indexed by an integer n 2 Z. At each time all the cells but a finite number are in state 0. Throughout the paper we make use of generating series and, from this point of view, a configuration is a Laure

Running the line: Linedrawing using runs and runs of runs

The efficiency of linedrawing algorithms underwrites the performance of many rendering and visualisation systems. Therefore to significantly improve the process of linedrawing, techniques have been developed to draw the line not pixel by pixel but by using higher order primitives such as runs and run length slices. In this paper we present a linedrawing algorithm based on runs of runs, which is the next step in this progression. We will also discuss a number of special cases in the structure of runs and runs of runs within the line that can be used to short circuit the drawing process. These special cases can be used to help counter a common criticism that run-based techniques are less applicable for very short lines. In fact we will argue that the use of higher order primitives provides additional structural information that can be used to accelerate secondary processes within the graphics system, such as within the raster memory management