A new problem in string searching

We describe a substring search problem that arises in group presentation simplification processes. We suggest a two-level searching model: skip and match levels. We give two timestamp algorithms which skip searching parts of the text where there are no matches at all and prove their correctness. At the match level, we consider Harrison signature, Karp-Rabin fingerprint, Bloom filter and automata based matching algorithms and present experimental performance figures.Comment: To appear in Proceedings Fifth Annual International Symposium on Algorithms and Computation (ISAAC'94), Lecture Notes in Computer Scienc

Parallel Quick-Skip Search Hybrid Algorithm For The Exact String Matching Problem.

Masalah padanan rententan merupakan mercu tanda dalam kebanyakan bidang sains komputer kerana peranan yang dimainkannya dalam pelbagai aplikasi komputer. The string matching problem occupies a corner stone in many computer science fields because of the fundamental role it plays in various computer applications

Network intrusion detection system using string matching

Network intrusion detection system is a retrofit approach for providing a sense of security in existing computers and data networks, while allowing them to operate in their current open mode. The goal of a network intrusion detection system is to identify, preferably in real time, unauthorized use, misuse and abuse of computer systems by insiders as well as from outside perpetrators. At the heart of every network intrusion detection system is packet inspection which employs nothing but string matching. This string matching is the bottleneck of performance for the whole network intrusion detection system. Thus, the need to increase the performance of string matching cannot be more exemplified. In this project, we have studied some of the standard string matching algorithms and implemented them. We have then compared the performance of the various algorithms with varying input sizes. The main focus of the project was the Aho-Corasick algorithm. In addition to using the default implementation of suffix trees, we have used a dense hash set and a sparse hash set implementation- which are libraries from the Google code repository- and we show that the performance for these implementations are better. They give noticeable enhancement in performance when the input size increases

Implementation SHA512 Hash Function And Boyer-Moore String Matching Algorithm For Jpeg/exif Message Digest Compilation

Security information method for JPEG/exif documents generally aims to prevent security attacks by protecting documents with password and watermark. Both methods cannot be used to determine the condition of data integrity at the detection stage of the information security cycle. Message Digest is the essence of a file that has a function as a digital fingerprint to represent data integrity. This study aims to compile digital fingerprints to detect changes that occurred in JPEG / exif documents in information security. The research phase consists of five stages. The first stage, identification of the JPEG / exif document structure conducted using the Boyer-Moore string matching algorithm to find JPEG/exif segments location. The Second stage is segment content acquisition, conducted based on segment location and length obtained. The Third step, computing message digest for each segment using SHA512 hash function. Fourth stage, JPEG / exif document modification experiments to identified affected segments. The fifth stage is selecting and combining the hash value of the segment into the message digest. The obtained result shows the message digest for JPEG/exif documents composed of three hash values. The SOI segment hash value used to detect modifications for JPEG to png conversion and image editing. The APP1 hash value used to detect metadata editing. The SOF0 hash values use to detect modification for image recoloring, cropping and resizing — the combination from three hash values as JPEG/exif’s message digest

Analysis of Parallel Boyer-Moore String Search Algorithm

Boyer Moore string matching algorithm is one of the famous algorithms used in string search algorithms. Widely, it is used in sequential form which presents good performance. In this paper a parallel implementation of Boyer Moore algorithm is proposed and evaluated. Experimental results show that it is valuable with zero overhead and cost optimal. The comparison between sequential and parallel showed that the parallel implementation was faster and more useful