The Stringdist Package for Approximate String Matching by Mark P.J
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Headprint: Detecting Anomalous Communications Through Header-Based Application Fingerprinting
HeadPrint: Detecting Anomalous Communications through Header-based Application Fingerprinting Riccardo Bortolameotti Thijs van Ede Andrea Continella University of Twente University of Twente UC Santa Barbara [email protected] [email protected] [email protected] Thomas Hupperich Maarten H. Everts Reza Rafati University of Muenster University of Twente Bitdefender [email protected] [email protected] [email protected] Willem Jonker Pieter Hartel Andreas Peter University of Twente Delft University of Technology University of Twente [email protected] [email protected] [email protected] ABSTRACT 1 INTRODUCTION Passive application fingerprinting is a technique to detect anoma- Data breaches are a major concern for enterprises across all indus- lous outgoing connections. By monitoring the network traffic, a tries due to the severe financial damage they cause [25]. Although security monitor passively learns the network characteristics of the many enterprises have full visibility of their network traffic (e.g., applications installed on each machine, and uses them to detect the using TLS-proxies) and they stop many cyber attacks by inspect- presence of new applications (e.g., malware infection). ing traffic with different security solutions (e.g., IDS, IPS, Next- In this work, we propose HeadPrint, a novel passive fingerprint- Generation Firewalls), attackers are still capable of successfully ing approach that relies only on two orthogonal network header exfiltrating data. Data exfiltration often occurs over network covert characteristics to distinguish applications, namely the order of the channels, which are communication channels established by attack- headers and their associated values. Our approach automatically ers to hide the transfer of data from a security monitor. -
Intelligent Chat Bot
INTELLIGENT CHAT BOT A. Mohamed Rasvi, V.V. Sabareesh, V. Suthajebakumari Computer Science and Engineering, Kamaraj College of Engineering and Technology, India ABSTRACT This paper discusses the workflow of intelligent chat bot powered by various artificial intelligence algorithms. The replies for messages in chats are trained against set of predefined questions and chat messages. These trained data sets are stored in database. Relying on one machine-learning algorithm showed inaccurate performance, so this bot is powered by four different machine-learning algorithms to make a decision. The inference engine pre-processes the received message then matches it against the trained datasets based on the AI algorithms. The AIML provides similar way of replying to a message in online chat bots using simple XML based mechanism but the method of employing AI provides accurate replies than the widely used AIML in the Internet. This Intelligent chat bot can be used to provide assistance for individual like answering simple queries to booking a ticket for a trip and also when trained properly this can be used as a replacement for a teacher which teaches a subject or even to teach programming. Keywords : AIML, Artificial Intelligence, Chat bot, Machine-learning, String Matching. I. INTRODUCTION Social networks are attracting masses and gaining huge momentum. They allow instant messaging and sharing features. Guides and technical help desks provide on demand tech support through chat services or voice call. Queries are taken to technical support team from customer to clear their doubts. But this process needs a dedicated support team to answer user‟s query which is a lot of man power. -
Author Guidelines for 8
I.J. Information Technology and Computer Science, 2014, 01, 68-75 Published Online December 2013 in MECS (http://www.mecs-press.org/) DOI: 10.5815/ijitcs.2014.01.08 FSM Circuits Design for Approximate String Matching in Hardware Based Network Intrusion Detection Systems Dejan Georgiev Faculty of Electrical Engineering and Information Technologies , Skopje, Macedonia E-mail: [email protected] Aristotel Tentov Faculty of Electrical Engineering and Information Technologies, Skopje, Macedonia E-mail: [email protected] Abstract— In this paper we present a logical circuits to perform a check to a possible variations of the design for approximate content matching implemented content because of so named "evasion" techniques. as finite state machines (FSM). As network speed Software systems have processing limitations in that increases the software based network intrusion regards. On the other hand hardware platforms, like detection and prevention systems (NIDPS) are lagging FPGA offer efficient implementation for high speed behind requirements in throughput of so called deep network traffic. package inspection - the most exhaustive process of Excluding the regular expressions as special case ,the finding a pattern in package payloads. Therefore, there problem of approximate content matching basically is a is a demand for hardware implementation. k-differentiate problem of finding a content Approximate content matching is a special case of content finding and variations detection used by C c1c2.....cm in a string T t1t2.......tn such as the "evasion" techniques. In this research we will enhance distance D(C,X) of content C and all the occurrences of the k-differentiate problem with "ability" to detect a a substring X is less or equal to k , where k m n . -
Comparison of Levenshtein Distance Algorithm and Needleman-Wunsch Distance Algorithm for String Matching
COMPARISON OF LEVENSHTEIN DISTANCE ALGORITHM AND NEEDLEMAN-WUNSCH DISTANCE ALGORITHM FOR STRING MATCHING KHIN MOE MYINT AUNG M.C.Sc. JANUARY2019 COMPARISON OF LEVENSHTEIN DISTANCE ALGORITHM AND NEEDLEMAN-WUNSCH DISTANCE ALGORITHM FOR STRING MATCHING BY KHIN MOE MYINT AUNG B.C.Sc. (Hons:) A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Computer Science (M.C.Sc.) University of Computer Studies, Yangon JANUARY2019 ii ACKNOWLEDGEMENTS I would like to take this opportunity to express my sincere thanks to those who helped me with various aspects of conducting research and writing this thesis. Firstly, I would like to express my gratitude and my sincere thanks to Prof. Dr. Mie Mie Thet Thwin, Rector of the University of Computer Studies, Yangon, for allowing me to develop this thesis. Secondly, my heartfelt thanks and respect go to Dr. Thi Thi Soe Nyunt, Professor and Head of Faculty of Computer Science, University of Computer Studies, Yangon, for her invaluable guidance and administrative support, throughout the development of the thesis. I am deeply thankful to my supervisor, Dr. Ah Nge Htwe, Associate Professor, Faculty of Computer Science, University of Computer Studies, Yangon, for her invaluable guidance, encouragement, superior suggestion and supervision on the accomplishment of this thesis. I would like to thank Daw Ni Ni San, Lecturer, Language Department of the University of Computer Studies, Yangon, for editing my thesis from the language point of view. I thank all my teachers who taught and helped me during the period of studies in the University of Computer Studies, Yangon. Finally, I am grateful for all my teachers who have kindly taught me and my friends from the University of Computer Studies, Yangon, for their advice, their co- operation and help for the completion of thesis. -
Algorithms for Approximate String Matching Petro Protsyk (28 October 2016) Agenda
Algorithms for approximate string matching Petro Protsyk (28 October 2016) Agenda • About ZyLAB • Overview • Algorithms • Brute-force recursive Algorithm • Wagner and Fischer Algorithm • Algorithms based on Automaton • Bitap • Q&A About ZyLAB ZyLAB is a software company headquartered in Amsterdam. In 1983 ZyLAB was the first company providing a full-text search program for MS-DOS called ZyINDEX In 1991 ZyLAB released ZyIMAGE software bundle that included a fuzzy string search algorithm to overcome scanning and OCR errors. Currently ZyLAB develops eDiscovery and Information Governance solutions for On Premises, SaaS and Cloud installations. ZyLAB continues to develop new versions of its proprietary full-text search engine. 3 About ZyLAB • We develop for Windows environments only, including Azure • Software developed in C++, .Net, SQL • Typical clients are from law enforcement, intelligence, fraud investigators, law firms, regulators etc. • FTC (Federal Trade Commission), est. >50 TB (peak 2TB per day) • US White House (all email of presidential administration), est. >20 TB • Dutch National Police, est. >20 TB 4 ZyLAB Search Engine Full-text search engine • Boolean and Proximity search operators • Support for Wildcards, Regular Expressions and Fuzzy search • Support for numeric and date searches • Search in document fields • Near duplicate search 5 ZyLAB Search Engine • Highly parallel indexing and searching • Can index Terabytes of data and millions of documents • Can be distributed • Supports 100+ languages, Unicode characters 6 Overview Approximate string matching or fuzzy search is the technique of finding strings in text or dictionary that match given pattern approximately with respect to chosen edit distance. The edit distance is the number of primitive operations necessary to convert the string into an exact match. -
An Ensemble Regression Approach for Ocr Error Correction
AN ENSEMBLE REGRESSION APPROACH FOR OCR ERROR CORRECTION by Jie Mei Submitted in partial fulfillment of the requirements for the degree of Master of Computer Science at Dalhousie University Halifax, Nova Scotia March 2017 © Copyright by Jie Mei, 2017 Table of Contents List of Tables ................................... iv List of Figures .................................. v Abstract ...................................... vi List of Symbols Used .............................. vii Acknowledgements ............................... viii Chapter 1 Introduction .......................... 1 1.1 Problem Statement............................ 1 1.2 Proposed Model .............................. 2 1.3 Contributions ............................... 2 1.4 Outline ................................... 3 Chapter 2 Background ........................... 5 2.1 OCR Procedure .............................. 5 2.2 OCR-Error Characteristics ........................ 6 2.3 Modern Post-Processing Models ..................... 7 Chapter 3 Compositional Correction Frameworks .......... 9 3.1 Noisy Channel ............................... 11 3.1.1 Error Correction Models ..................... 12 3.1.2 Correction Inferences ....................... 13 3.2 Confidence Analysis ............................ 16 3.2.1 Error Correction Models ..................... 16 3.2.2 Correction Inferences ....................... 17 3.3 Framework Comparison ......................... 18 ii Chapter 4 Proposed Model ........................ 21 4.1 Error Detection .............................. 22 -
Automating Error Frequency Analysis Via the Phonemic Edit Distance Ratio
JSLHR Research Note Automating Error Frequency Analysis via the Phonemic Edit Distance Ratio Michael Smith,a Kevin T. Cunningham,a and Katarina L. Haleya Purpose: Many communication disorders result in speech corresponds to percent segments with these phonemic sound errors that listeners perceive as phonemic errors. errors. Unfortunately, manual methods for calculating phonemic Results: Convergent validity between the manually calculated error frequency are prohibitively time consuming to use in error frequency and the automated edit distance ratio was large-scale research and busy clinical settings. The purpose excellent, as demonstrated by nearly perfect correlations of this study was to validate an automated analysis based and negligible mean differences. The results were replicated on a string metric—the unweighted Levenshtein edit across 2 speech samples and 2 computation applications. distance—to express phonemic error frequency after left Conclusions: The phonemic edit distance ratio is well hemisphere stroke. suited to estimate phonemic error rate and proves itself Method: Audio-recorded speech samples from 65 speakers for immediate application to research and clinical practice. who repeated single words after a clinician were transcribed It can be calculated from any paired strings of transcription phonetically. By comparing these transcriptions to the symbols and requires no additional steps, algorithms, or target, we calculated the percent segments with a combination judgment concerning alignment between target and production. of phonemic substitutions, additions, and omissions and We recommend it as a valid, simple, and efficient substitute derived the phonemic edit distance ratio, which theoretically for manual calculation of error frequency. n the context of communication disorders that affect difference between a series of targets and a series of pro- speech production, sound error frequency is often ductions. -
Practice with Python
CSI4108-01 ARTIFICIAL INTELLIGENCE 1 Word Embedding / Text Processing Practice with Python 2018. 5. 11. Lee, Gyeongbok Practice with Python 2 Contents • Word Embedding – Libraries: gensim, fastText – Embedding alignment (with two languages) • Text/Language Processing – POS Tagging with NLTK/koNLPy – Text similarity (jellyfish) Practice with Python 3 Gensim • Open-source vector space modeling and topic modeling toolkit implemented in Python – designed to handle large text collections, using data streaming and efficient incremental algorithms – Usually used to make word vector from corpus • Tutorial is available here: – https://github.com/RaRe-Technologies/gensim/blob/develop/tutorials.md#tutorials – https://rare-technologies.com/word2vec-tutorial/ • Install – pip install gensim Practice with Python 4 Gensim for Word Embedding • Logging • Input Data: list of word’s list – Example: I have a car , I like the cat → – For list of the sentences, you can make this by: Practice with Python 5 Gensim for Word Embedding • If your data is already preprocessed… – One sentence per line, separated by whitespace → LineSentence (just load the file) – Try with this: • http://an.yonsei.ac.kr/corpus/example_corpus.txt From https://radimrehurek.com/gensim/models/word2vec.html Practice with Python 6 Gensim for Word Embedding • If the input is in multiple files or file size is large: – Use custom iterator and yield From https://rare-technologies.com/word2vec-tutorial/ Practice with Python 7 Gensim for Word Embedding • gensim.models.Word2Vec Parameters – min_count: -
NLP - Assignment 2
NLP - Assignment 2 Week 2 December 27th, 2016 1. A 5-gram model is a order Markov Model: (a) Six (b) Five (c) Four (d) Constant Ans : c) Four 2. For the following corpus C1 of 3 sentences, what is the total count of unique bi- grams for which the likelihood will be estimated? Assume we do not perform any pre-processing, and we are using the corpus as given. (i) ice cream tastes better than any other food (ii) ice cream is generally served after the meal (iii) many of us have happy childhood memories linked to ice cream (a) 22 (b) 27 (c) 30 (d) 34 Ans : b) 27 3. Arrange the words \curry, oil and tea" in descending order, based on the frequency of their occurrence in the Google Books n-grams. The Google Books n-gram viewer is available at https://books.google.com/ngrams: (a) tea, oil, curry (c) curry, tea, oil (b) curry, oil, tea (d) oil, tea, curry Ans: d) oil, tea, curry 4. Given a corpus C2, The Maximum Likelihood Estimation (MLE) for the bigram \ice cream" is 0.4 and the count of occurrence of the word \ice" is 310. The likelihood of \ice cream" after applying add-one smoothing is 0:025, for the same corpus C2. What is the vocabulary size of C2: 1 (a) 4390 (b) 4690 (c) 5270 (d) 5550 Ans: b)4690 The Questions from 5 to 10 require you to analyse the data given in the corpus C3, using a programming language of your choice. -
Hardware Pattern Matching for Network Traffic Analysis in Gigabit
Technische Universitat¨ Munchen¨ Fakultat¨ fur¨ Informatik Diplomarbeit in Informatik Hardware Pattern Matching for Network Traffic Analysis in Gigabit Environments Gregor M. Maier Aufgabenstellerin: Prof. Anja Feldmann, Ph. D. Betreuerin: Prof. Anja Feldmann, Ph. D. Abgabedatum: 15. Mai 2007 Ich versichere, dass ich diese Diplomarbeit selbst¨andig verfasst und nur die angegebe- nen Quellen und Hilfsmittel verwendet habe. Datum Gregor M. Maier Abstract Pattern Matching is an important task in various applica- tions, including network traffic analysis and intrusion detec- tion. In modern high speed gigabit networks it becomes un- feasible to search for patterns using pure software implemen- tations, due to the amount of data that must be searched. Furthermore applications employing pattern matching often need to search for several patterns at the same time. In this thesis we explore the possibilities of using FPGAs for hardware pattern matching. We analyze the applicability of various pattern matching algorithms for hardware imple- mentation and implement a Rabin-Karp and an approximate pattern matching algorithm in Endace’s network measure- ment cards using VHDL. The implementations are evalu- ated and compared to pure software matching solutions. To demonstrate the power of hardware pattern matching, an example application for traffic accounting using hardware pattern matching is presented as a proof-of-concept. Since some systems like network intrusion detection systems an- alyze reassembled TCP streams, possibilities for hardware TCP reassembly combined with hardware pattern matching are discussed as well. Contents vii Contents List of Figures ix 1 Introduction 1 1.1 Motivation . 1 1.2 Related Work . 2 1.3 About Endace DAG Network Monitoring Cards . -
Tries and String Matching
Tries and String Matching Where We've Been ● Fundamental Data Structures ● Red/black trees, B-trees, RMQ, etc. ● Isometries ● Red/black trees ≡ 2-3-4 trees, binomial heaps ≡ binary numbers, etc. ● Amortized Analysis ● Aggregate, banker's, and potential methods. Where We're Going ● String Data Structures ● Data structures for storing and manipulating text. ● Randomized Data Structures ● Using randomness as a building block. ● Integer Data Structures ● Breaking the Ω(n log n) sorting barrier. ● Dynamic Connectivity ● Maintaining connectivity in an changing world. String Data Structures Text Processing ● String processing shows up everywhere: ● Computational biology: Manipulating DNA sequences. ● NLP: Storing and organizing huge text databases. ● Computer security: Building antivirus databases. ● Many problems have polynomial-time solutions. ● Goal: Design theoretically and practically efficient algorithms that outperform brute-force approaches. Outline for Today ● Tries ● A fundamental building block in string processing algorithms. ● Aho-Corasick String Matching ● A fast and elegant algorithm for searching large texts for known substrings. Tries Ordered Dictionaries ● Suppose we want to store a set of elements supporting the following operations: ● Insertion of new elements. ● Deletion of old elements. ● Membership queries. ● Successor queries. ● Predecessor queries. ● Min/max queries. ● Can use a standard red/black tree or splay tree to get (worst-case or expected) O(log n) implementations of each. A Catch ● Suppose we want to store a set of strings. ● Comparing two strings of lengths r and s takes time O(min{r, s}). ● Operations on a balanced BST or splay tree now take time O(M log n), where M is the length of the longest string in the tree. -
Algorithm for Character Recognition Based on the Trie Structure
University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1987 Algorithm for character recognition based on the trie structure Mohammad N. Paryavi The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Paryavi, Mohammad N., "Algorithm for character recognition based on the trie structure" (1987). Graduate Student Theses, Dissertations, & Professional Papers. 5091. https://scholarworks.umt.edu/etd/5091 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. COPYRIGHT ACT OF 1 9 7 6 Th is is an unpublished manuscript in which copyright sub s i s t s , Any further r e p r in t in g of its contents must be approved BY THE AUTHOR, Ma n sfield L ibrary U n iv e r s it y of Montana Date : 1 987__ AN ALGORITHM FOR CHARACTER RECOGNITION BASED ON THE TRIE STRUCTURE By Mohammad N. Paryavi B. A., University of Washington, 1983 Presented in partial fulfillment of the requirements for the degree of Master of Science University of Montana 1987 Approved by lairman, Board of Examiners iean, Graduate School UMI Number: EP40555 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted.