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Computer Science Technical Reports

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Articles 151 - 180 of 772

Full-Text Articles in Computer Sciences

Functional Monitoring Without Monotonicity, Chrisil Arackaparambil, Joshua Brody, Amit Chakrabarti Dec 2008

Functional Monitoring Without Monotonicity, Chrisil Arackaparambil, Joshua Brody, Amit Chakrabarti

Computer Science Technical Reports

The notion of distributed functional monitoring was recently introduced by Cormode, Muthukrishnan and Yi to initiate a formal study of the communication cost of certain fundamental problems arising in distributed systems, especially sensor networks. In this model, each of k sites reads a stream of tokens and is in communication with a central coordinator, who wishes to continuously monitor some function f of \sigma, the union of the k streams. The goal is to minimize the number of bits communicated by a protocol that correctly monitors f(\sigma), to within some small error. As in previous work, we focus on a …


Digital Image Ballistics From Jpeg Quantization: A Followup Study, Hany Farid Dec 2008

Digital Image Ballistics From Jpeg Quantization: A Followup Study, Hany Farid

Computer Science Technical Reports

The lossy JPEG compression scheme employs a quantization table that controls the amount of compression achieved. Because different cameras typically employ different tables, a comparison of an image's quantization scheme to a database of known cameras affords a simple technique for confirming or denying an image's source. This report describes the analysis of quantization tables extracted from 1,000,000 images downloaded from Flickr.com.


Toward Evaluating Lighting Design Interface Paradigms For Novice Users, William Brandon Kerr, Fabio Pellacini Nov 2008

Toward Evaluating Lighting Design Interface Paradigms For Novice Users, William Brandon Kerr, Fabio Pellacini

Computer Science Technical Reports

Lighting design is a complex and fundamental task in computer cinematography, involving adjustment of light parameters to define final scene appearance. Many lighting interfaces have been proposed to improve lighting design work flow. These paradigms exist in three paradigm categories: direct light parameter manipulation, indirect light feature manipulation (e.g., shadow dragging), and goal-based optimization of light through painting. To this date, no formal evaluation of the relative effectiveness of these methods has been performed. In this paper, we present a first step toward evaluating the three paradigms in the form of a user study with novice users. We focus our …


Blac: Revoking Repeatedly Misbehaving Anonymous Users Without Relying On Ttps, Patrick P. Tsang, Man Ho Au, Apu Kapadia, Sean W. Smith Oct 2008

Blac: Revoking Repeatedly Misbehaving Anonymous Users Without Relying On Ttps, Patrick P. Tsang, Man Ho Au, Apu Kapadia, Sean W. Smith

Computer Science Technical Reports

Several credential systems have been proposed in which users can authenticate to service providers anonymously. Since anonymity can give users the license to misbehave, some variants allow the selective deanonymization (or linking) of misbehaving users upon a complaint to a trusted third party (TTP). The ability of the TTP to revoke a user's privacy at any time, however, is too strong a punishment for misbehavior. To limit the scope of deanonymization, systems have been proposed in which users are deanonymized if they authenticate ``too many times,'' such as ``double spending'' with electronic cash. While useful in some applications, it is …


Lzfuzz: A Fast Compression-Based Fuzzer For Poorly Documented Protocols, Sergey Bratus, Axel Hansen, Anna Shubina Sep 2008

Lzfuzz: A Fast Compression-Based Fuzzer For Poorly Documented Protocols, Sergey Bratus, Axel Hansen, Anna Shubina

Computer Science Technical Reports

Real-world infrastructure offers many scenarios where protocols (and other details) are not released due to being considered too sensitive or for other reasons. This situation makes it hard to apply fuzzing techniques to test their security and reliability, since their full documentation is only available to their developers, and domain developer expertise does not necessarily intersect with fuzz-testing expertise (nor deployment responsibility). State-of-the-art fuzzing techniques, however, work best when protocol specifications are available. Still, operators whose networks include equipment communicating via proprietary protocols should be able to reap the benefits of fuzz-testing them. In particular, administrators should be able to …


Detecting Kernel Rootkits, Ashwin Ramaswamy Sep 2008

Detecting Kernel Rootkits, Ashwin Ramaswamy

Computer Science Technical Reports

Kernel rootkits are a special category of malware that are deployed directly in the kernel and hence have unmitigated reign over the functionalities of the kernel itself. We seek to detect such rootkits that are deployed in the real world by first observing how the majority of kernel rootkits operate. To this end, comparable to how rootkits function in the real world, we write our own kernel rootkit that manipulates the network driver, thus giving us control over all packets sent into the network. We then implement a mechanism to thwart the attacks of such rootkits by noticing that a …


Twokind Authentication: Protecting Private Information In Untrustworthy Environments (Extended Version), Katelin Bailey, Apu Kapadia, Linden Vongsathorn, Sean W. Smith Aug 2008

Twokind Authentication: Protecting Private Information In Untrustworthy Environments (Extended Version), Katelin Bailey, Apu Kapadia, Linden Vongsathorn, Sean W. Smith

Computer Science Technical Reports

We propose and evaluate TwoKind Authentication, a simple and effective technique that allows users to limit access to their private information in untrustworthy environments. Users often log in to Internet sites from insecure computers, and more recently have started divulging their email passwords to social-networking sites, thereby putting their private communications at risk. To mitigate this problem, we explore the use of multiple authenticators for the same account that are associated with specific sets of privileges. In its simplest form, TwoKind features two modes of authentication, a low and a high authenticator. By using a low authenticator, users can signal …


Yasir: A Low-Latency, High-Integrity Security Retrofit For Legacy Scada Systems (Extended Version), Patrick P. Tsang, Sean W. Smith Apr 2008

Yasir: A Low-Latency, High-Integrity Security Retrofit For Legacy Scada Systems (Extended Version), Patrick P. Tsang, Sean W. Smith

Computer Science Technical Reports

We construct a bump-in-the-wire (BITW) solution that retrofits security into time-critical communications over bandwidth-limited serial links between devices in legacy Supervisory Control And Data Acquisition (SCADA) systems, on which the proper operations of critical infrastructures such as the electric power grid rely. Previous BITW solutions do not provide the necessary security within timing constraints; the previous solution that does is not BITW. At a hardware cost comparable to existing solutions, our BITW solution provides sufficient security, and yet incurs minimal end-to-end communication latency.


The Weakest Failure Detector To Solve Mutual Exclusion, Vibhor Bhatt, Nicholas Christman, Prasad Jayanti Apr 2008

The Weakest Failure Detector To Solve Mutual Exclusion, Vibhor Bhatt, Nicholas Christman, Prasad Jayanti

Computer Science Technical Reports

Mutual exclusion is not solvable in an asynchronous message-passing system where processes are subject to crash failures. Delporte-Gallet et. al. determined the weakest failure detector to solve this problem when a majority of processes are correct. Here we identify the weakest failure detector to solve mutual exclusion in any environment, i.e., regardless of the number of faulty processes. We also show a relation between mutual exclusion and consensus, arguably the two most fundamental problems in distributed computing. Specifically, we show that a failure detector that solves mutual exclusion is sufficient to solve non-uniform consensus but not necessarily uniform consensus.


Ppaa: Peer-To-Peer Anonymous Authentication (Extended Version), Patrick P. Tsang, Sean W. Smith Apr 2008

Ppaa: Peer-To-Peer Anonymous Authentication (Extended Version), Patrick P. Tsang, Sean W. Smith

Computer Science Technical Reports

In the pursuit of authentication schemes that balance user privacy and accountability, numerous anonymous credential systems have been constructed. However, existing systems assume a client-server architecture in which only the clients, but not the servers, care about their privacy. In peer-to-peer (P2P) systems where both clients and servers are peer users with privacy concerns, no existing system correctly strikes that balance between privacy and accountability. In this paper, we provide this missing piece: a credential system in which peers are {\em pseudonymous} to one another (that is, two who interact more than once can recognize each other via pseudonyms) but …


Bounded Unpopularity Matchings, Chien-Chung Huang, Telikepalli Kavitha, Dimitrios Michail, Meghana Nasre Apr 2008

Bounded Unpopularity Matchings, Chien-Chung Huang, Telikepalli Kavitha, Dimitrios Michail, Meghana Nasre

Computer Science Technical Reports

We investigate the following problem: given a set of jobs and a set of people with preferences over the jobs, what is the optimal way of matching people to jobs? Here we consider the notion of \emph{popularity}. A matching $M$ is popular if there is no matching $M'$ such that more people prefer $M'$ to $M$ than the other way around. Determining whether a given instance admits a popular matching and, if so, finding one, was studied in \cite{AIKM05}. If there is no popular matching, a reasonable substitute is a matching whose {\em unpopularity} is bounded. We consider two measures …


Active Behavioral Fingerprinting Of Wireless Devices, Sergey Bratus, Cory Cornelius, David Kotz, Daniel Peebles Mar 2008

Active Behavioral Fingerprinting Of Wireless Devices, Sergey Bratus, Cory Cornelius, David Kotz, Daniel Peebles

Computer Science Technical Reports

We propose a simple active method for discovering facts about the chipset, the firmware or the driver of an 802.11 wireless device by observing its responses (or lack thereof) to a series of crafted non-standard or malformed 802.11 frames. We demonstrate that such responses can differ significantly enough to distinguish between a number of popular chipsets and drivers. We expect to significantly expand the number of recognized device types through community contributions of signature data for the proposed open fingerprinting framework. Our method complements known fingerprinting approaches, and can be used to interrogate and spot devices that may be spoofing …


Localized Bridging Centrality For Distributed Network Analysis, Soumendra Nanda, David Kotz Jan 2008

Localized Bridging Centrality For Distributed Network Analysis, Soumendra Nanda, David Kotz

Computer Science Technical Reports

Centrality is a concept often used in social network analysis to study different properties of networks that are modeled as graphs. We present a new centrality metric called Localized Bridging Centrality (LBC). LBC is based on the Bridging Centrality (BC) metric that Hwang et al. recently introduced. Bridging nodes are nodes that are located in between highly connected regions. LBC is capable of identifying bridging nodes with an accuracy comparable to that of the BC metric for most networks. As the name suggests, we use only local information from surrounding nodes to compute the LBC metric, while, global knowledge is …


Tr-2008007: Degeneration Of Structured Integer Matrices Modulo An Integer, Victor Y. Pan, Xinmao Wang Jan 2008

Tr-2008007: Degeneration Of Structured Integer Matrices Modulo An Integer, Victor Y. Pan, Xinmao Wang

Computer Science Technical Reports

No abstract provided.


Tr-2008008: Schur Aggregation For Linear Systems And Determinants, V. Y. Pan, D. Grady, B. Murphy, G. Qian, R. E. Rosholt, A. D. Ruslanov Jan 2008

Tr-2008008: Schur Aggregation For Linear Systems And Determinants, V. Y. Pan, D. Grady, B. Murphy, G. Qian, R. E. Rosholt, A. D. Ruslanov

Computer Science Technical Reports

No abstract provided.


Tr-2008015: An Efficient Heuristic For The Tree Alignment Problem, Andrés Varón, Ward Wheeler, Amotz Bar-Noy Jan 2008

Tr-2008015: An Efficient Heuristic For The Tree Alignment Problem, Andrés Varón, Ward Wheeler, Amotz Bar-Noy

Computer Science Technical Reports

No abstract provided.


Tr-2008013: Content-Based 3d Mosaics For Large-Scale Dynamic Urban Scenes, Hao Tang, Zhigang Zhu Jan 2008

Tr-2008013: Content-Based 3d Mosaics For Large-Scale Dynamic Urban Scenes, Hao Tang, Zhigang Zhu

Computer Science Technical Reports

No abstract provided.


Tr-2008012: Product-Free Lambek Calculus Is Np-Complete, Yury Savateev Jan 2008

Tr-2008012: Product-Free Lambek Calculus Is Np-Complete, Yury Savateev

Computer Science Technical Reports

No abstract provided.


Tr-2008011: Contrast Transfer Function Correction In Electron Microscopy, Joanna Klukowska Jan 2008

Tr-2008011: Contrast Transfer Function Correction In Electron Microscopy, Joanna Klukowska

Computer Science Technical Reports

No abstract provided.


Tr-2008002: On Image Reconstruction From A Small Number Of Projections, G. T. Herman, R. Davidi Jan 2008

Tr-2008002: On Image Reconstruction From A Small Number Of Projections, G. T. Herman, R. Davidi

Computer Science Technical Reports

No abstract provided.


Tr-2008001: Public And Private Communication Are Different: Results On Relative Expressivity, Bryan Renne Jan 2008

Tr-2008001: Public And Private Communication Are Different: Results On Relative Expressivity, Bryan Renne

Computer Science Technical Reports

No abstract provided.


Tr-2008003: Unified Nearly Optimal Algorithms For Structured Integer Matrices And Polynomials, Victor Y. Pan, Brian Murphy, Rhys E. Rosholt Jan 2008

Tr-2008003: Unified Nearly Optimal Algorithms For Structured Integer Matrices And Polynomials, Victor Y. Pan, Brian Murphy, Rhys E. Rosholt

Computer Science Technical Reports

No abstract provided.


Tr-2008004: Additive Preconditioning For Matrix Computations, Victor Y. Pan, Dmitriy Ivolgin, Brian Murphy, Rhys Eric Rosholt, Yuqing Tang, Xiaodong Yan Jan 2008

Tr-2008004: Additive Preconditioning For Matrix Computations, Victor Y. Pan, Dmitriy Ivolgin, Brian Murphy, Rhys Eric Rosholt, Yuqing Tang, Xiaodong Yan

Computer Science Technical Reports

No abstract provided.


Tr-2008005: Weakly Random Additive Preconditioning For Matrix Computations, Victor Y. Pan, Dmitriy Ivolgin, Brian Murphy, Rhys Eric Rosholt, Yuqing Tang, Xiaodong Yan Jan 2008

Tr-2008005: Weakly Random Additive Preconditioning For Matrix Computations, Victor Y. Pan, Dmitriy Ivolgin, Brian Murphy, Rhys Eric Rosholt, Yuqing Tang, Xiaodong Yan

Computer Science Technical Reports

No abstract provided.


Tr-2008016: An Analysis Of Entries In The First Tac Market Design Competition, Jinzhong Niu, Kai Cai, Simon Parsons, Peter Mcburney Jan 2008

Tr-2008016: An Analysis Of Entries In The First Tac Market Design Competition, Jinzhong Niu, Kai Cai, Simon Parsons, Peter Mcburney

Computer Science Technical Reports

No abstract provided.


Tr-2008006: Additive Preconditioning, Eigenspaces, And The Inverse Iteration, Victor Y. Pan, Xiaodong Yan Jan 2008

Tr-2008006: Additive Preconditioning, Eigenspaces, And The Inverse Iteration, Victor Y. Pan, Xiaodong Yan

Computer Science Technical Reports

No abstract provided.


Tr-2008009: Solving Homogeneous Linear Systems With Weakly Randomized Additive Preprocessing, Victor Y. Pan, Guoliang Qian Jan 2008

Tr-2008009: Solving Homogeneous Linear Systems With Weakly Randomized Additive Preprocessing, Victor Y. Pan, Guoliang Qian

Computer Science Technical Reports

No abstract provided.


Tr-2008010: The Logic Of Justification, Sergei Artemov Jan 2008

Tr-2008010: The Logic Of Justification, Sergei Artemov

Computer Science Technical Reports

No abstract provided.


Tr-2008014: Why Do We Need Justification Logic?, Sergei Artemov Jan 2008

Tr-2008014: Why Do We Need Justification Logic?, Sergei Artemov

Computer Science Technical Reports

No abstract provided.


Two's Company, Three's A Crowd: Stable Family And Threesome Roommates Problems, Chien-Chung Huang Dec 2007

Two's Company, Three's A Crowd: Stable Family And Threesome Roommates Problems, Chien-Chung Huang

Computer Science Technical Reports

We investigate Knuth's eleventh open question on stable matchings. In the stable family problem, sets of women, men, and dogs are given, all of whom state their preferences among the other two groups. The goal is to organize them into family units, so that no three of them have the incentive to desert their assigned family members to form a new family. A similar problem, called the threesome roommates problem, assumes that a group of persons, each with their preferences among the combinations of two others, are to be partitioned into triples. Similarly, the goal is to make sure that …