HURRICANE! - A SIMULATION-BASED PROGRAM FOR SCIENCE EDUCATION

Jia Luo
Alpesh P. Makwana
Dezhi Liao
J. Peter Kincaid

Institute for Simulation and Training
3100 Technology Parkway
University of Central Florida
Orlando, FL 32826 USA

ABSTRACT
We describe the development, testing and fielding of a PC-based instructional program, Hurricane!. This program educates students about the effects of hurricane winds on different kinds of residential structures.The effects on the residential structures are physics-based. The program has been developed both for schools and science museums. The format is game-based with realistic graphics and sounds and students see different degrees of damage depending
on choices that make. For example, a one story masonry house built to current Florida building code standards, is much less vulnerable than a two story wood structure built before 1985. Therefore, students who make the first choice see less damage. Several tests in middle school science classes have demonstrated that the game is highly interesting and effectively teaches concepts central to understanding how to prepare for a hurricane.

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Distortion-Free Steganography for Polygonal Meshes

Alexander Bogomjakov Craig Gotsman Martin Isenburg

Center for Graphics and Geometric Computing - Technion - Israel Institute of Technology Center for Applied Scientific Computing - Lawrence Livermore National Labs

Abstract

We present a technique for steganography in polygonal meshes. Our method hides a message in the indexed representation of a mesh by permuting the order in which faces and vertices are stored. The permutation is relative to a reference ordering that encoder and decoder derive from the mesh connectivity in a consistent manner. Our method is distortion-free because it does not modify the geometry of the mesh. Compared to previous steganographic methods for polygonal meshes our capacity is up to an order of magnitude better. Our steganography algorithm is universal and can be used instead of the standard permutation steganography algorithm on arbitrary datasets. The standard algorithm runs in O(n2 log2 n loglog n) time and achieves optimal O(nlogn) bit capacity on datasets with n elements. In contrast, our algorithm runs in O(n) time, achieves a capacity that is only one bit per element less than optimal, and is extremely simple to implement.

Categories and Subject Descriptors (according to ACM CCS): I.3.m [Computer Graphics]: Miscellaneous

1. Introduction
Steganography (or, more simply, data-hiding) is the science of hiding messages in media in such a way that even the existence of the message remains undetected to all but the recipient. This is in contrast with cryptography, where the fact that a message is hidden in the data is not disguised, but it may be retrieved only by the use of a secret key, typically known only to the recipient. Thus, steganographic messages do not attract attention to themselves, to messengers, or to recipients. A classic example is invisible ink that turns brown when the paper is heated. An inconspicuous cover message is important as a blank sheet of paper can arouse suspicion.

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Evolution of the Internet AS-Level Ecosystem

Srinivas Shakkottai
Texas A&M University
College Station, USA

Marina Fomenkov
Cooperative Association for Internet Data Analysis - CAIDA
San Diego Supercomputer Center,
University of California, San Diego

Ryan Koga
Cooperative Association for Internet Data Analysis - CAIDA
San Diego Supercomputer Center,
University of California, San Diego

Dmitri Krioukov
Cooperative Association for Internet Data Analysis - CAIDA
San Diego Supercomputer Center,
University of California, San Diego

kc claffy
Cooperative Association for Internet Data Analysis - CAIDA
San Diego Supercomputer Center,
University of California, San Diego

Abstract. We present an analytically tractable model of Internet evolution at the level of Autonomous Systems (ASs). We call our model the multiclass preferential attachment (MPA) model. As its name suggests, it is based on preferential attachment. All of its parameters are measurable from available Internet topology data. Given the estimated values of these parameters, our analytic results predict a defnitive set of statistics characterizing the AS topology structure. These statistics are not part of model formulation. The MPA model thus closes the \measure-modelvalidate-predict" loop, and provides further evidence that preferential attachment is the main driving force behind Internet evolution.

Key words: Preferential attachment, Internet evolution, AS-level topology, Internet measurement

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Short Paper: Mobile Proactive Secret Sharing

David Schultz
Massachusetts Institute of Technology
das@csail.mit.edu

Barbara Liskov
Massachusetts Institute of Technology
liskov@csail.mit.edu

Moses Liskov
The College of William and Mary
mliskov@cs.wm.edu

ABSTRACT

MPSS is a new way to do proactive secret sharing in asynchronous networks. MPSS provides mobility: The group of nodes holding the shares of the secret can change at each resharing, which is essential in a long-lived system. MPSS additionally allows the number of tolerated faulty shareholders to change when the secret is moved so that the system can tolerate more (or fewer) corruptions; this allows reconfiguration on the fly to accommodate changes in the environment.

Categories and Subject Descriptors

C.2.4 [Computer Communication Networks]: Distributed Systems--distributed applications

General Terms

Security

1. INTRODUCTION

Malicious attacks are an increasing problem in distributed systems. If a node holds an important secret, that secret could be exposed by an attack in which an intruder gains control of that machine. An example of such a secret is the private key used by a certificate authority (such as Verisign) to sign its certificates.
Secret sharing allows a group of servers to possess shares of a secret, such that any t + 1 servers can collaborate to compute with the secret, but any t or fewer servers can learn nothing about the secret. Proactive secret sharing extends secret sharing to work in a long-lived system, in which nodes can become compromised over time, allowing the adversary to collect more than t shares and recover the secret. These schemes provide a share regeneration protocol, in which a new set of shares of the same secret is generated and the old shares discarded, rendering useless any collection of t or fewer old shares the adversary may have learned.

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