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Many network security applications rely on string matching to detect intrusions, viruses, spam, and so on. Since software implementation may not keep pace with the high-speed demand, turning to hardware-based solutions becomes promising. This work presents an innovative architecture to realize string matching in sub-linear time based on algorithmic heuristics, which come from parallel queries to a set of space-efficient Bloom filters. The algorithm allows skipping characters not in a match in the text, and in turn simultaneously inspect multiple characters in effect. The techniques to reduce the impact of certain bad situations on performance are also proposed: the bad-block heuristic, a linear worst-case time method and a non-blocking interface to hand over the verification job to a verification module. This architecture is simulated with both behavior simulation in C and timing simulation in HDL for antivirus applications. The simulation shows that the throughput of scanning Windows executable files for more than 10000 virus signatures can achieve 5.64 Gb/s, while the worst-case performance is 1.2 Gb/s if the signatures are properly specified.
Very Large Scale Integration (VLSI) Systems, IEEE Transactions on (Volume:17 , Issue: 8 )
Date of Publication: Aug. 2009