Pairing computation on hyperelliptic curves of genus 2

Bilinear pairings have been recently used to construct cryptographic schemes with new and novel properties, the most celebrated example being the Identity Based Encryption scheme of Boneh and Franklin. As pairing computation is generally the most computationally intensive part of any painng-based cryptosystem, it is essential to investigate new ways in which to compute pairings efficiently. The vast majority of the literature on pairing computation focuscs solely on using elliptic curves. In this thesis we investigate pairing computation on supersingular hyperelliptic curves of genus 2 Our aim is to provide a practical alternative to using elliptic curves for pairing based cryptography. Specifically, we illustrate how to implement pairings efficiently using genus 2 curves, and how to attain performance comparable to using elliptic curves. We show that pairing computation on genus 2 curves over F2m can outperform elliptic curves by using a new variant of the Tate pairing, called the r¡j pairing, to compute the fastest pairing implementation in the literature to date We also show for the first time how the final exponentiation required to compute the Tate pairing can be avoided for certain hyperelliptic curves. We investigate pairing computation using genus 2 curves over large prime fields, and detail various techniques that lead to an efficient implementation, thus showing that these curves are a viable candidate for practical use

Extracting scene feature vectors through modeling, volume 3

The remote estimation of the leaf area index of winter wheat at Finney County, Kansas was studied. The procedure developed consists of three activities: (1) field measurements; (2) model simulations; and (3) response classifications. The first activity is designed to identify model input parameters and develop a model evaluation data set. A stochastic plant canopy reflectance model is employed to simulate reflectance in the LANDSAT bands as a function of leaf area index for two phenological stages. An atmospheric model is used to translate these surface reflectances into simulated satellite radiance. A divergence classifier determines the relative similarity between model derived spectral responses and those of areas with unknown leaf area index. The unknown areas are assigned the index associated with the closest model response. This research demonstrated that the SRVC canopy reflectance model is appropriate for wheat scenes and that broad categories of leaf area index can be inferred from the procedure developed

Formal Methods Specification and Analysis Guidebook for the Verification of Software and Computer Systems

This guidebook, the second of a two-volume series, is intended to facilitate the transfer of formal methods to the avionics and aerospace community. The 1st volume concentrates on administrative and planning issues [NASA-95a], and the second volume focuses on the technical issues involved in applying formal methods to avionics and aerospace software systems. Hereafter, the term "guidebook" refers exclusively to the second volume of the series. The title of this second volume, A Practitioner's Companion, conveys its intent. The guidebook is written primarily for the nonexpert and requires little or no prior experience with formal methods techniques and tools. However, it does attempt to distill some of the more subtle ingredients in the productive application of formal methods. To the extent that it succeeds, those conversant with formal methods will also nd the guidebook useful. The discussion is illustrated through the development of a realistic example, relevant fragments of which appear in each chapter. The guidebook focuses primarily on the use of formal methods for analysis of requirements and high-level design, the stages at which formal methods have been most productively applied. Although much of the discussion applies to low-level design and implementation, the guidebook does not discuss issues involved in the later life cycle application of formal methods

A cybernetic development of epistemology and observation applied to objects in space and time (as seen in architecture)

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This Thesis proposes a new epistemological ontology which has two peculiar characteristics: Objects in its Universe are formulated as being self-observers (i. e. reflexive); and the nature of observation of Objects by others is shown to contain the logic for computing relationships between Objects in the Universe. This Universe is non-hierarchical, and permits of mutually contradictory beliefs about its Objects to be simultaneously held by different observers. The logic by which observers construct hierarchies in the Universe is shown to need only one variable in order to operate, and to operate from the oscillatory nature of the self-observing Objects producing. a sense of local time in both observer, and observed Objects; the times of which must temporarily come together for observations to be made. Using these notions of Objects and observations, a means, based on the potential for observers to construct 0 hierarchies, is found for analysing arguments, and (potentially) for the improvement of computer performance. A way is described for the representation of observations of Objects to be made, and a conversational idiom is established to account for communication between different observers. The views put forward in this Thesis are demonstrated by various experiments, stories, and references

Developing a catalogue of errors and evaluating its impact on software development

The development of quality software is of paramount importance, yet this has been and continues to be an elusive goal for software engineers. Delivered software often fails due to errors that are injected during its development. Correcting these errors early in the development or preventing them altogether can, therefore, be considered as one way to improve software quality. In this thesis, the development of a Catalogue of Errors is described. Field studies with senior software engineering students are used to confirm that developers using the Catalogue of Errors commit fewer errors in their development artifacts. The impact of the Catalogue of Errors on productivity is also examined

Accounting Historians Journal, 1992, Vol. 19, no. 2 [whole issue]

December issu

Objectworlds : a class of computer-based discovery learning environments

It is possible to discern a class of Computer-Based Discovery Learning Environments which centre on novel, concept rich,simulated objects and which include simple but general functions with which the objects may be manipulated. This thesis provides a history of this class of environments, which we call objectworlds, and we also give them a strict definition. We describe Gravitas, a new objectworld we have built, which allows learners to work with objects that behave like gravitating masses moving in a two dimensional space.Gravitas contains a powerful programmable interface to the objects, in the form of a set of Logo commands, and a functionally equivalent but easier to use graphical interface which is controlled by the mouse. We show that the combination of interfaces helps learners to explore the world of these objects more effectively.We contrast the educational experiences learners are afforded by objectworlds with those offered by two closely related kinds of Discovery Learning Environment: Simulations and Modelling Systems. We also describe a psychological framework which provides a useful way of thinking about the construction of computer simulated objects for discovery learning applications

An entropy maximization approach to the description of urban spatial organization

Bibliography: leaves [173]-190