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Exploiting Underlying Structure for Detailed Reconstruction of an Internetscale Event
 In Proc. ACM SIGCOMM Internet Measurement Conference
, 2005
"... Abstract Network telescopes that record packets sent to unused blocks of Internet address space have emerged as an important tool for observing Internetscale events such as the spread of worms and the backscatter from ooding attacks that use spoofed source addresses. Current telescope analyses pr ..."
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Cited by 57 (6 self)
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Abstract Network telescopes that record packets sent to unused blocks of Internet address space have emerged as an important tool for observing Internetscale events such as the spread of worms and the backscatter from ooding attacks that use spoofed source addresses. Current telescope analyses produce detailed tabulations of packet rates, victim population, and evolution over time. While such cataloging is a crucial rst step in studying the telescope observations, incorporating an understanding of the underlying processes generating the observations allows us to construct detailed inferences about the broader universe in which the Internetscale activity occurs, greatly enriching and deepening the analysis in the process. In this work we apply such an analysis to the propagation of the Witty worm, a malicious and wellengineered worm that when released in March 2004 infected more than 12,000 hosts worldwide in 75 minutes. We show that by carefully exploiting the structure of the worm, especially its pseudorandom number generation, from limited and imperfect telescope data we can with high delity: extract the individual rate at which each infectee injected packets into the network prior to loss; correct distortions in the telescope data due to the worm’s volume overwhelming the monitor; reveal the worm’s inability to fully reach all of its potential victims; determine the number of disks attached to each infected machine; compute when each infectee was last booted, to subsecond accuracy; explore the who infected whom infection tree; uncover that the worm specically targeted hosts at a US military base; and pinpoint Patient Zero, the initial point of infection, i.e., the IP address of the system the attacker used to unleash Witty. I.
Building Certified Libraries for PCC: Dynamic Storage Allocation
, 2003
"... ProofCarrying Code (PCC) allows a code producer to provide to a host a program along with its formal safety proof. The proof attests a certain safety policy enforced by the code, and can be mechanically checked by the host. While this languagebased approach to code certification is very general in ..."
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Cited by 43 (9 self)
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ProofCarrying Code (PCC) allows a code producer to provide to a host a program along with its formal safety proof. The proof attests a certain safety policy enforced by the code, and can be mechanically checked by the host. While this languagebased approach to code certification is very general in principle, existing PCC systems have only focused on programs whose safety proofs can be automatically generated.
How to read floating point numbers accurately
 Proceedings of PLDI ’90
, 1990
"... Converting decimal scientific notation into binary floating point is nontrivial, but this conversion can be performed with the best possible accuracy without sacrificing efficiency. 1. ..."
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Cited by 25 (0 self)
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Converting decimal scientific notation into binary floating point is nontrivial, but this conversion can be performed with the best possible accuracy without sacrificing efficiency. 1.
Pattern avoidance in binary trees
 J. Combin. Theory, Ser. A
"... Abstract. This paper introduces the notion of pattern avoidance in binary trees. We provide an algorithm for computing the generating function that counts the number of nleaf binary trees avoiding a given binary tree pattern t. Equipped with this counting mechanism, we study the analogue of Wilf eq ..."
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Cited by 11 (2 self)
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Abstract. This paper introduces the notion of pattern avoidance in binary trees. We provide an algorithm for computing the generating function that counts the number of nleaf binary trees avoiding a given binary tree pattern t. Equipped with this counting mechanism, we study the analogue of Wilf equivalence in which two tree patterns are equivalent if the respective trees that avoid them are equinumerous. We investigate the equivalence classes combinatorially, finding some relationships to Dyck words avoiding a given subword. Toward establishing bijective proofs of tree pattern equivalence, we develop a general method of restructuring trees that (conjecturally) always succeeds to produce an explicit bijection. 1.
A Survey, Discussion and Comparison of Sorting Algorithms by
, 2014
"... Sorting is a basic task in many types of computer applications. Especially when large amounts of data are to be sorted, efficiency becomes a major issue. There are many different sorting algorithms and even more ways in which they can be implemented. The efficiency of real implementations is often a ..."
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Sorting is a basic task in many types of computer applications. Especially when large amounts of data are to be sorted, efficiency becomes a major issue. There are many different sorting algorithms and even more ways in which they can be implemented. The efficiency of real implementations is often at least as important as the theoretical efficiency of the abstract algorithm. For example, Quicksort is wellknown to perform very well in most practical situations, regardless of the fact that many other sorting algorithms have a better worstcase behaviour. The goal of this master thesis is to make a survey of sorting algorithms and discuss and compare the differences in both theory and practice. There are several features that interests in this thesis such as finding possible implementations of each algorithm and discuss their properties and administer considerable experiments in order to obtain empirical data about their practical efficiency in different situations. Finally we present the comparison of different sorting algorithms with their practical efficiency and conclude the theoretical findings and the knowledge gained from this study.
1.1 Pattern Analysis for Computer Security.............................................................................................................. 7
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Sponsored by CarletonOttawa Mathematics Association Mathematique d"OttawaCarleton A Chapter of the Ontario Association for Mathematics Education
, 1978
"... The CMS is pleased to offer free access to its back file of all issues of Crux as a service for the greater mathematical community in Canada and beyond. Journal title history: ➢ The first 32 issues, from Vol. 1, No. 1 (March 1975) to Vol. 4, No.2 (February 1978) were published under the name EUREKA. ..."
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The CMS is pleased to offer free access to its back file of all issues of Crux as a service for the greater mathematical community in Canada and beyond. Journal title history: ➢ The first 32 issues, from Vol. 1, No. 1 (March 1975) to Vol. 4, No.2 (February 1978) were published under the name EUREKA.
Systematic Conformational Search with
, 2002
"... Throughout biological, chemical, and pharmaceutical research, conformational searches are used to explore the possible threedimensional con gurations of molecules. This thesis describes a new systematic method for conformational search, including an application of the method to determining the str ..."
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Throughout biological, chemical, and pharmaceutical research, conformational searches are used to explore the possible threedimensional con gurations of molecules. This thesis describes a new systematic method for conformational search, including an application of the method to determining the structure of a peptide via solidstate NMR spectroscopy. A separate portion of the thesis is about proteinDNA binding, with a threedimensional macromolecular structure determined by xray crystallography. The search method in this thesis enumerates all conformations of a molecule (at a given level of torsion angle resolution) that satisfy a set of local geometric constraints, such as constraints derived from NMR experiments. Systematic searches, historically used for small molecules, generally now use some form of divideandconquer for application to larger molecules. Our method can achieve a signicant improvement