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Computer Science Technical Reports

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Full-Text Articles in Computer Sciences

Controlling Access To Pervasive Information In The “Solar” System, Kazuhiro Minami, David Kotz Feb 2002

Controlling Access To Pervasive Information In The “Solar” System, Kazuhiro Minami, David Kotz

Computer Science Technical Reports

Pervasive-computing infrastructures necessarily collect a lot of context information to disseminate to their context-aware applications. Due to the personal or proprietary nature of much of this context information, however, the infrastructure must limit access to context information to authorized persons. In this paper we propose a new access-control mechanism for event-based context-distribution infrastructures. The core of our approach is based on a conservative information-flow model of access control, but users may express discretionary relaxation of the resulting access-control list (ACL) by specifying relaxation functions. This combination of automatic ACL derivation and user-specified ACL relaxation allows access control to be determined …


Trusted Paths For Browsers: An Open-Source Solution To Web Spoofing, Zishuang (Eileen) Ye, Sean Smith Feb 2002

Trusted Paths For Browsers: An Open-Source Solution To Web Spoofing, Zishuang (Eileen) Ye, Sean Smith

Computer Science Technical Reports

The security of the vast majority of ``secure'' Web services rests on SSL server PKI. However, this PKI doesn't work if the the adversary can trick the browser into appearing to tell the user the wrong thing about the certificates and cryptography. The seminal web spoofing work of Felten et al demonstrated the potential, in 1996, for malicious servers to impersonate honest servers. Our recent follow-up work explicitly shows how malicious servers can still do this---and can also forge the existence of an SSL session and the contents of the alleged server certificate. This paper reports the results of our …


Virtual Hierarchies - An Architecture For Building And Maintaining Efficient And Resilient Trust Chains, John Marchesini, Sean Smith Feb 2002

Virtual Hierarchies - An Architecture For Building And Maintaining Efficient And Resilient Trust Chains, John Marchesini, Sean Smith

Computer Science Technical Reports

In Public Key Infrastructure (PKI), the simple, monopolistic CA model works fine until we consider the real world. Then, issues such as scalability and mutually suspicious organizations create the need for a multiplicity of CAs, which immediately introduces the problem of how to organize them to balance resilience to compromise against efficiency of path discovery. However, security has given us tools such as secure coprocessing, secret splitting, secret sharing, and threshold cryptography for securely carrying out computations among multiple trust domains; distributed computing has given us peer-to-peer networking, for creating self-organizing distributed systems. In this paper, we use these latter …


Ffts For The 2-Sphere - Improvements And Variations, D M. Healy Jr, D N. Rockmore, P J. Kostelec, Sean S.B. Moore Feb 2002

Ffts For The 2-Sphere - Improvements And Variations, D M. Healy Jr, D N. Rockmore, P J. Kostelec, Sean S.B. Moore

Computer Science Technical Reports

Earlier work by Driscoll and Healy has produced an efficient algorithm for computing the Fourier transform of band-limited functions on the 2-sphere. In this paper we present a reformulation and variation of the original algorithm which results in a greatly improved inverse transform, and consequent improved convolution algorithm for such functions. All require at most $O(N\log^2 N)$ operations where $N$ is the number of sample points. We also address implementation considerations and give heuristics for allowing reliable and computationally efficient floating point implementations of slightly modified algorithms. These claims are supported by extensive numerical experiments from our implementation in C …


Web Spoofing Revisited: Ssl And Beyond, Eileen Zishuang Ye, Yougu Yuan, Sean Smith Feb 2002

Web Spoofing Revisited: Ssl And Beyond, Eileen Zishuang Ye, Yougu Yuan, Sean Smith

Computer Science Technical Reports

Can users believe what their browsers tell them? Even sophisticated Web users decide whether or not to trust a server based on browser cues such as location bar information, SSL icons, SSL warnings, certificate information, and response time. In their seminal work on Web spoofing, Felten et al showed how, in 1996, a malicious server could forge some of these cues. However, this work used genuine SSL sessions, and Web technology has evolved much since 1996. The Web has since become the pre-eminent medium for electronic service delivery to remote users, and the security of many commerce, government, and academic …


Future Directions For Mobile-Agent Research, David Kotz, Robert Gray, Daniela Rus Jan 2002

Future Directions For Mobile-Agent Research, David Kotz, Robert Gray, Daniela Rus

Computer Science Technical Reports

During a discussion in September 2000 the authors examined the future of research on mobile agents and mobile code. (A mobile agent is a running program that can move from host to host in network at times and to places of its own choosing.) In this paper we summarize and reflect on that discussion. It became clear that the field should shift its emphasis toward mobile code, in all its forms, rather than to continue its narrow focus on mobile agents. Furthermore, we encourage the development of modular components, so that application designers may take advantage of code mobility without …


Tr-2002003: Univariate Polynomial Root-Finding With A Lower Computational Precision And Higher Convergence Rates, V. Y. Pan Jan 2002

Tr-2002003: Univariate Polynomial Root-Finding With A Lower Computational Precision And Higher Convergence Rates, V. Y. Pan

Computer Science Technical Reports

No abstract provided.


Tr-2002001: Can We Optimize Toeplitz/Hankel Computations?, V. Y. Pan Jan 2002

Tr-2002001: Can We Optimize Toeplitz/Hankel Computations?, V. Y. Pan

Computer Science Technical Reports

No abstract provided.


Tr-2002002: Can We Optimize Toeplitz/Hankel Computations? Ii. Singular Toeplitz/Hankel-Like Case, V. Y. Pan Jan 2002

Tr-2002002: Can We Optimize Toeplitz/Hankel Computations? Ii. Singular Toeplitz/Hankel-Like Case, V. Y. Pan

Computer Science Technical Reports

No abstract provided.


Tr-2002005: Towards A Theory Of Social Software, Rohit Parikh Jan 2002

Tr-2002005: Towards A Theory Of Social Software, Rohit Parikh

Computer Science Technical Reports

No abstract provided.


Tr-2002008: Investigation Of The Sensitivity Of The Monte Carlo Solution For The Barker-Ferry Equation Using Different Sequential And Parallel Pseudo-Random Number Generators, T. V. Gurov, P. A. Whitlock Jan 2002

Tr-2002008: Investigation Of The Sensitivity Of The Monte Carlo Solution For The Barker-Ferry Equation Using Different Sequential And Parallel Pseudo-Random Number Generators, T. V. Gurov, P. A. Whitlock

Computer Science Technical Reports

No abstract provided.


Tr-2002004: On The Effectiveness Of Tangible Interfaces In Collaborative Learning Environments, Lori L. Scarlatos, Shalva S. Landy, Julia Breban, Robin Horowitz, Chanie Sandberg Jan 2002

Tr-2002004: On The Effectiveness Of Tangible Interfaces In Collaborative Learning Environments, Lori L. Scarlatos, Shalva S. Landy, Julia Breban, Robin Horowitz, Chanie Sandberg

Computer Science Technical Reports

No abstract provided.


Tr-2002007: Ubiquitous Puzzle Pieces: 3d Tangible Interfaces For Collaborative Learning Environments, Lori L. Scarlatos, Shalva S. Landy, Saira Qureshi Jan 2002

Tr-2002007: Ubiquitous Puzzle Pieces: 3d Tangible Interfaces For Collaborative Learning Environments, Lori L. Scarlatos, Shalva S. Landy, Saira Qureshi

Computer Science Technical Reports

No abstract provided.


Tr-2002011: Corpus-Based Ambiguity Resolution Of Biomedical Terms Using Knowledge Bases And Machine Learning, Hongfang Liu Jan 2002

Tr-2002011: Corpus-Based Ambiguity Resolution Of Biomedical Terms Using Knowledge Bases And Machine Learning, Hongfang Liu

Computer Science Technical Reports

No abstract provided.


Tr-2002012: The Aggregation And Cancellation Techniques As A Practical Tool For Faster Matrix Multiplication, Igor Kaporin Jan 2002

Tr-2002012: The Aggregation And Cancellation Techniques As A Practical Tool For Faster Matrix Multiplication, Igor Kaporin

Computer Science Technical Reports

No abstract provided.


Tr-2002013: Toward A High-Performance System For Symbolic And Statistical Modeling, Neng-Fa Zhou, Taisuke Sato Jan 2002

Tr-2002013: Toward A High-Performance System For Symbolic And Statistical Modeling, Neng-Fa Zhou, Taisuke Sato

Computer Science Technical Reports

No abstract provided.


Tr-2002015: Residual Correction Algorithms For General And Structured Matrices, V. Y. Pan, M. Kunin, R. E. Rosholt, H. Cebecioglu Jan 2002

Tr-2002015: Residual Correction Algorithms For General And Structured Matrices, V. Y. Pan, M. Kunin, R. E. Rosholt, H. Cebecioglu

Computer Science Technical Reports

No abstract provided.


Tr-2002017: Nearly Optimal Toeplitz/Hankel Computations, Victor Y. Pan Jan 2002

Tr-2002017: Nearly Optimal Toeplitz/Hankel Computations, Victor Y. Pan

Computer Science Technical Reports

No abstract provided.


Tr-2002016: Optimization Of Basis Functions For Both Reconstruction And Visualization, Edgar Garduño, Gabor T. Herman Jan 2002

Tr-2002016: Optimization Of Basis Functions For Both Reconstruction And Visualization, Edgar Garduño, Gabor T. Herman

Computer Science Technical Reports

No abstract provided.


Tr-2002019: Improved Algorithms For Computing Determinants And Resultants, Ioannis Z. Emiris, Victor Y. Pan Jan 2002

Tr-2002019: Improved Algorithms For Computing Determinants And Resultants, Ioannis Z. Emiris, Victor Y. Pan

Computer Science Technical Reports

No abstract provided.


Tr-2002020: Inverse Power And Durand-Kerner Iterations For Univariate Polynomial Root-Finding, D. A. Bini, L. Gemignani, V. Y. Pan Jan 2002

Tr-2002020: Inverse Power And Durand-Kerner Iterations For Univariate Polynomial Root-Finding, D. A. Bini, L. Gemignani, V. Y. Pan

Computer Science Technical Reports

No abstract provided.


Tr-2002006: States Of Knowledge, Rohit Parikh Jan 2002

Tr-2002006: States Of Knowledge, Rohit Parikh

Computer Science Technical Reports

No abstract provided.


Tr-2002009: A Formal Semantics For Uml With Real-Time Constructs, Subash Shankar Jan 2002

Tr-2002009: A Formal Semantics For Uml With Real-Time Constructs, Subash Shankar

Computer Science Technical Reports

No abstract provided.


Tr-2002010: Programming Finite-Domain Constraint Propagators In Action Rules, Neng-Fa Zhou Jan 2002

Tr-2002010: Programming Finite-Domain Constraint Propagators In Action Rules, Neng-Fa Zhou

Computer Science Technical Reports

No abstract provided.


Tr-2002014: Iterative Inversion Of Structured Matrices, Gianni Codevico, Victor Y. Pan, Marc Van Barel, Xinmao Wang Jan 2002

Tr-2002014: Iterative Inversion Of Structured Matrices, Gianni Codevico, Victor Y. Pan, Marc Van Barel, Xinmao Wang

Computer Science Technical Reports

No abstract provided.


Tr-2002018: How Frequently Is A Matrix Nonsingular?, Xinmao Wang Jan 2002

Tr-2002018: How Frequently Is A Matrix Nonsingular?, Xinmao Wang

Computer Science Technical Reports

No abstract provided.


Decentralized Control For Coordinated Flow Of Multi-Agent Systems, Valentino Crespi, George Cybenko, Daniela Rus, Massimo Santini Jan 2002

Decentralized Control For Coordinated Flow Of Multi-Agent Systems, Valentino Crespi, George Cybenko, Daniela Rus, Massimo Santini

Computer Science Technical Reports

This paper describes a distributed algorithm for coordinating the flow of a mass of vehicles approaching a highway exit or a tollbooth. We provide the problem formulation, a general methodology for distributed control and an instantiation of this methodology to the coordinated flow problem. We analyze our algorithm and provide experimental data.


Differential Elastic Image Registration, Senthil Periaswamy, Hany Farid Sep 2001

Differential Elastic Image Registration, Senthil Periaswamy, Hany Farid

Computer Science Technical Reports

We have applied techniques from differential motion estimation to the problem of automatic elastic registration of medical images. This method models the mapping between images as a locally affine but globally smooth warp. The mapping also explicitly accounts for variations in image intensities. This approach is simple and highly effective across a broad range of medical images. We show the efficacy of this approach on several synthetic and clinical images.


Detecting Steganographic Messages In Digital Images, Hany Farid Sep 2001

Detecting Steganographic Messages In Digital Images, Hany Farid

Computer Science Technical Reports

Techniques and applications for information hiding have become increasingly more sophisticated and widespread. With high-resolution digital images as carriers, detecting the presence of hidden messages has also become considerably more difficult. It is sometimes possible, nevertheless, to detect (but not necessarily decipher) the presence of embedded messages. The basic approach taken here works by finding predictable higher-order statistics of ``natural'' images within a multi-scale decomposition, and then showing that embedded messages alter these statistics.


Write Once, Move Anywhere: Toward Dynamic Interoperability Of Mobile Agent Systems, Arne Grimstrup, Robert Gray, David Kotz, Thomas Cowin, Greg Hill, Niranjan Suri, Daria Chacon, Martin Hofmann Jul 2001

Write Once, Move Anywhere: Toward Dynamic Interoperability Of Mobile Agent Systems, Arne Grimstrup, Robert Gray, David Kotz, Thomas Cowin, Greg Hill, Niranjan Suri, Daria Chacon, Martin Hofmann

Computer Science Technical Reports

Mobile agents are an increasingly popular paradigm, and in recent years there has been a proliferation of mobile-agent systems. These systems are, however, largely incompatible with each other. In particular, agents cannot migrate to a host that runs a different mobile-agent system. Prior approaches to interoperability have tried to force agents to use a common API, and so far none have succeeded. Our goal, summarized in the catch phrase ``Write Once, Move Anywhere,'' led to our efforts to develop mechanisms that support dynamic runtime interoperability of mobile-agent systems. This paper describes the Grid Mobile-Agent System, which allows agents to migrate …