Method for compressing space of deterministic automaton
A space compression and automaton technology, applied in the field of network security, can solve the problem of not being able to improve the DFA space conversion speed at the same time, and achieve the effect of improving the matching speed and the compression effect.
Inactive Publication Date: 2012-01-25
INST OF COMPUTING TECH CHINESE ACAD OF SCI
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[0016] The purpose of the present invention is to overcome the defect that the prior art cannot simultaneously improve the compression effect of the DFA space and the conversion speed of the DFA state, thereby providing a method for achieving a good balance between the compression effect and the conversion speed
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[0062] The present invention will be described below with reference to the drawings and specific embodiments.
[0063] In this embodiment, taking the regular expression ".*A.{2}CD" as an example, the process of compressing the DFA space of the regular expression is described.
[0064] First, the corresponding DFA is generated from the regular expression ".*A.{2}CD". Since the process of generating DFA from regular expressions is a well-known technique in the art, the description will not be repeated here. in figure 1 A schematic diagram of the DFA generated by the regular expression ".*A.{2}CD" is given in. In this figure, the numbers 0, 1, 2, 3 in the circle represent states, and the DFA has 10 states from 0-9. The horizontal line with an arrow represents the condition of transition from one state to another. The letters on the arrow, such as A, C, D, Not A (representing any character other than A), represent the specific content of the condition. These horizontal lines with ar...
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The invention provides a method for compressing the space of a finite automaton, comprising the steps: executing each status in the finite automaton in a clustering way to obtain a plurality of clusters for expressing a status set; classifying transfer edges of the each status in the finite automaton according to the clusters so as to obtain a plurality of cluster matrixes, bitmaps corresponding to the cluster matrixes and remaining matrixes, wherein the cluster matrixes comprise transfer edges for pointing to the same cluster, the bitmaps are used for describing the effectiveness of correlative elements in the cluster matrixes corresponding thereto, and the remaining matrixes comprise remaining transfer edges which are not contained in the cluster matrixes in the finite automaton; and extracting a basic value for each row in the cluster matrixes, converting the cluster matrixes into an offset matrix, merging the each row in the offset matrix, and adding with a index data set for marking a status which can be merged, to obtain compression matrixes of the cluster matrixes. The method improves not only compression effect but also matching speed when realizing regular expression match.
Description
Technical field [0001] The present invention relates to the field of network security, in particular to a space compression method for determining automata. Background technique [0002] Regular expression is a single string used in computer science to describe or match a series of strings that conform to a certain syntax rule. The method of using regular expressions to match text content that conforms to a certain pattern is also called regular expression matching algorithms. Regular expression matching algorithm has always been one of the research focuses of computer science. It is widely used in network intrusion detection, computer virus signature matching, network information content security, information retrieval and other fields. [0003] Deterministic Automata (DFA) is the basis of regular expression matching algorithms. DFA is stored in the computer as a state transition table. Generally, the basic process of using DFA for regular expression matching is as follows: [00...
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IPC IPC(8): G06F17/30
Inventor 杨毅夫刘燕兵刘萍郭莉
Owner INST OF COMPUTING TECH CHINESE ACAD OF SCI