A Parallel Automaton String Matching with Pre-Hashing and Root-Indexing Techniques for Content Filtering Coprocessor

  • Authors:
  • Kuo-Kun Tseng;Ying-Dar Lin;Tsern-Huei Lee;Yuan-Cheng Lai

  • Affiliations:
  • National Chiao Tung University, Taiwan;National Chiao Tung University, Taiwan;National Chiao Tung University, Taiwan;National Taiwan University of Science and Technology, Taiwan

  • Venue:
  • ASAP '05 Proceedings of the 2005 IEEE International Conference on Application-Specific Systems, Architecture Processors
  • Year:
  • 2005

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Abstract

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.