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A parallel automaton string matching with pre-hashing and root-indexing techniques for content filtering coprocessor

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4 Author(s)
Kuo-Kun Tseng ; National Chiao Tung Univ., Taiwan ; Ying-Dar Lin ; Tsern-Huei Lee ; Yuan-Cheng Lai

We propose a new parallel automaton string matching approach and its hardware architecture for content filtering coprocessor. This new approach can improve the average matching time of the parallel automaton with pre-hashing and root-indexing techniques. The pre-hashing technique uses a hashing function to verify quickly the text against the partial patterns in the automaton, and the root-indexing technique matches multiple bytes for the root state in one single matching. A popular automaton algorithm, Aho-Corasick (AC) is chosen to be implemented by adding the two techniques; we employ these two techniques in a memory efficient version of AC namely bitmap AC. For the average-case time, our approach improves bitmap AC by 494% and 224% speedup for URL and virus patterns, respectively. Since pre-hashing and root-indexing techniques can be concurrently executed with bitmap AC in the hardware, our proposed approach has the same worst-case time as bitmap AC.

Published in:

Application-Specific Systems, Architecture Processors, 2005. ASAP 2005. 16th IEEE International Conference on

Date of Conference:

23-25 July 2005