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Showing papers by "Michael T. Goodrich published in 2003"


Book ChapterDOI
13 Apr 2003
TL;DR: It is demonstrated that the Micali-Sidney scheme is a special case of this general framework for shared generation of pseudo-random function using cumulative maps, and an upper and a lower bound for d are derived.
Abstract: In Crypto '95, Micali and Sidney proposed a method for shared generation of a pseudo-random function f(ċ) among n players in such a way that for all the inputs x, any u players can compute f(x) while t or fewer players fail to do so, where 0 ≤ t < u ≤ n. The idea behind the Micali-Sidney scheme is to generate and distribute secret seeds S = {s1, ..., sd} of a poly-random collection of functions, among the n players, each player gets a subset of S, in such a way that any u players together hold all the secret seeds in S while any t or fewer players will lack at least one element from S. The pseudo-random function is then computed as f(x) = ⊕i=1d fsi (x), where fsi (ċ)'s are poly-random functions. One question raised by Micali and Sidney is how to distribute the secret seeds satisfying the above condition such that the number of seeds, d, is as small as possible. In this paper, we continue the work of Micali and Sidney.We first provide a general framework for shared generation of pseudo-random function using cumulative maps. We demonstrate that the Micali-Sidney scheme is a special case of this general construction.We then derive an upper and a lower bound for d. Finally we give a simple, yet efficient, approximation greedy algorithm for generating the secret seeds S in which d is close to the optimum by a factor of at most u ln 2.

97 citations


Book
12 Feb 2003
TL;DR: This book presents even the most difficult mathematical concepts clearly, and emphasizes the practical application of the latest software engineering practices.
Abstract: * Presents a consistent object-oriented perspective* Recursion emphasized throughout, particularly in chapters 2 and 4* Design patterns provide clear approaches for developing programs* Offers a unique multimedia format for learning the fundamentals of data structures and algorithms* A robust set of end-of-chapter problems are arranged by purpose - reinforcement problems assess understanding; creativity problems require students to apply concepts to writing "classes" (portions of a program); projects require students to write entire programs* Outstanding writing style presents even the most difficult mathematical concepts clearly* "Visual Proofs" helps students better understand complex analytic concepts* Animations on the text's Web site clearly illustrate data structures and algorithms* Exercises offer numerous opportunities for hands-on learning* Emphasizes the practical application of the latest software engineering practices

67 citations


Book ChapterDOI
21 Sep 2003
TL;DR: In this article, the authors present several challenging and interesting open problems in graph drawing, and the goal of the listing in this paper is to stimulate future research on graph drawing problems.
Abstract: In this manuscript, we present several challenging and interesting open problems in graph drawing. The goal of the listing in this paper is to stimulate future research in graph drawing.

60 citations


Proceedings ArticleDOI
12 Jan 2003
TL;DR: This paper presents an efficient method for interpolating a piecewise-linear surface between two parallel slices, each consisting of an arbitrary number of (possibly nested) polygons that define 'material' and 'nonmaterial' regions.
Abstract: In this paper we present an efficient method for interpolating a piecewise-linear surface between two parallel slices, each consisting of an arbitrary number of (possibly nested) polygons that define 'material' and 'nonmaterial' regions. This problem has applications to medical imaging, geographic information systems, etc. Our method is fully automatic and is guaranteed to produce non-self-intersecting surfaces in all cases regardless of the number of contours in each slice, their complexity and geometry, and the depth of their hierarchy of nesting. The method is based on computing cells in the overlay of the slices, that form the symmetric difference between them. Then, the straight skeletons of the selected cells guide the triangulation of these cells. Finally, the resulting triangles are lifted up in space to form an interpolating surface. We provide some experimental results on various complex examples to show the good and robust performance of our algorithm.

51 citations


Book ChapterDOI
28 May 2003
TL;DR: While the motivation here is the dissemination of credential status data from multiple credential issuers, applications of this technology also include time stamping of documents, document version integrity control, and multiple-CA certificate revocation management, to name just a few.
Abstract: We describe several schemes for efficiently populating an authenticated dictionary with fresh credentials. The thrust of this effort is directed at allowing for many data authors, called sources, to collectively publish information to a common repository, which is then distributed throughout a network to allow for authenticated queries on this information. Authors are assured of their contributions being added to the repository based on cryptographic receipts that the repository returns after performing the updates sent by an author. While our motivation here is the dissemination of credential status data from multiple credential issuers, applications of this technology also include time stamping of documents, document version integrity control, and multiple-CA certificate revocation management, to name just a few.

37 citations


Journal Article
TL;DR: In this article, a technique called confluent drawing is proposed to visualize non-planar graphs in a planar way, which allows groups of edges to be merged together and drawn as tracks (similar to train tracks).
Abstract: We introduce a new approach for drawing diagrams. Our approach is to use a technique we call confluent drawing for visualizing non-planar graphs in a planar way. This approach allows us to draw, in a crossing-free manner, graphs-such as software interaction diagrams-that would normally have many crossings. The main idea of this approach is quite simple: we allow groups of edges to be merged together and drawn as tracks (similar to train tracks). Producing such confluent diagrams automatically from a graph with many crossings is quite challenging, however, so we offer two heuristic algorithms to test if a non-planar graph can be drawn efficiently in a confluent way. In addition, we identify several large classes of graphs that can be completely categorized as being either confluently drawable or confluently non-drawable.

29 citations


01 Dec 2003
TL;DR: It is proved that a malicious adversary which attacks the algorithm during the process of construction of a k-system cannot learn anything more than if it had attacked the k- system once it was built.
Abstract: We propose a bandwidth-efficient algorithmic solution for perfectly-secure communication in the absence of secure infrastructure. Our solution involves connecting vertex pairs by a set of k edge-disjoint paths (a structure we call a k-system) where k is a parameter determined by the connectivity of the network. This structure is resilient to adversaries with bounded eavesdropping capability. To ensure that bandwidth is efficiently used we consider connection requests as inputs to the k-Edge Disjoint Path Coloring Problem (k-EDPCOL), a generalization of the Path Coloring Problem, in which each vertex pair is connected by a k-system, and each k-system is assigned a color such that two overlapping k-systems do not have the same color. The objective is to minimize the number of colors. We give a distributed and competitive online algorithm for k-EDPCOL. Additionally, since security applications are our focus we prove that a malicious adversary which attacks the algorithm during the process of construction of a k-system cannot learn anything more than if it had attacked the k-system once it was built.

18 citations


Journal ArticleDOI
TL;DR: This paper presents a novel approach for cluster-based drawing of large planar graphs that maintains planarity and produces a clustering which satisfies the conditions for compound-planarity (c- Planarity).
Abstract: In this paper we present a novel approach for cluster-based drawing of large planar graphs that maintains planarity. Our technique works for arbitrary planar graphs and produces a clustering which satisfies the conditions for compound-planarity (c-planarity). Using the clustering, we obtain a representation of the graph as a collection of O(log n) layers, where each succeeding layer represents the graph in an increasing level of detail. At the same time, the difference between two graphs on neighboring layers of the hierarchy is small, thus preserving the viewer's mental map. The overall running time of the algorithm is O(n log n), where n is the number of vertices of graph G.

16 citations


Book ChapterDOI
01 Oct 2003
TL;DR: In this paper, the authors proposed a bandwidth-efficient algorithm for perfectly secure communication in the absence of secure infrastructure, which involves connecting vertex pairs by a set of k edge-disjoint paths, where k is a parameter determined by the connectivity of the network.
Abstract: We propose a bandwidth-efficient algorithmic solution for perfectly-secure communication in the absence of secure infrastructure. Our solution involves connecting vertex pairs by a set of k edge-disjoint paths (a structure we call a k-system) where k is a parameter determined by the connectivity of the network. This structure is resilient to adversaries with bounded eavesdropping capability. To ensure that bandwidth is efficiently used we consider connection requests as inputs to the k-Edge Disjoint Path Coloring Problem (k-EDPCOL), a generalization of the Path Coloring Problem, in which each vertex pair is connected by a k-system, and each k-system is assigned a color such that two overlapping k-systems do not have the same color. The objective is to minimize the number of colors. We give a distributed and competitive online algorithm for k-EDPCOL. Additionally, since security applications are our focus we prove that a malicious adversary which attacks the algorithm during the process of construction of a k-system cannot learn anything more than if it had attacked the k-system once it was built.

14 citations


Book ChapterDOI
30 Jul 2003
TL;DR: This work presents an efficient linear-time algorithm which draws edges and vertices of varying 2-dimensional areas to represent the amount of information flowing through them, and avoids all occlusions of nodes and edges.
Abstract: We consider the problem of representing size information in the edges and vertices of a planar graph. Such information can be used, for example, to depict a network of computers and information traveling through the network. We present an efficient linear-time algorithm which draws edges and vertices of varying 2-dimensional areas to represent the amount of information flowing through them. The algorithm avoids all occlusions of nodes and edges, while still drawing the graph on a compact integer grid.

4 citations


Proceedings ArticleDOI
22 Apr 2003
TL;DR: The functionality of a distributed system that supports the wide-scale deployment of an authenticated map is demonstrated and can be easily extended to support applications that use authenticated maps, including certificate revocation, document integrity, and digital rights management.
Abstract: We demonstrate the functionality of a distributed system that supports the wide-scale deployment of an authenticated map. The system can be easily extended to support applications that use authenticated maps, including certificate revocation, document integrity, and digital rights management.


Proceedings ArticleDOI
22 Apr 2003
TL;DR: This work overviews the theoretical and practical contributions and discusses future research directions on the subject of authenticated data structures, with applications to the development of a trust infrastructure for dynamic coalitions.
Abstract: We overview our work on the subject of authenticated data structures, with applications to the development of a trust infrastructure for dynamic coalitions. We summarize our theoretical and practical contributions and discuss future research directions.

Journal ArticleDOI
TL;DR: In this article, memory-efficient deterministic algorithms for constructing epsilon-networks and Epsilon-approximations of streams of geometric data are presented. But they do not provide guaranteed bounds on their approximation factors.
Abstract: We present memory-efficient deterministic algorithms for constructing epsilon-nets and epsilon-approximations of streams of geometric data. Unlike probabilistic approaches, these deterministic samples provide guaranteed bounds on their approximation factors. We show how our deterministic samples can be used to answer approximate online iceberg geometric queries on data streams. We use these techniques to approximate several robust statistics of geometric data streams, including Tukey depth, simplicial depth, regression depth, the Thiel-Sen estimator, and the least median of squares. Our algorithms use only a polylogarithmic amount of memory, provided the desired approximation factors are inverse-polylogarithmic. We also include a lower bound for non-iceberg geometric queries.