A path combinational method for multiple pattern matching

Multiple pattern matching architecture is critical for content inspection based network security applications, especially for high speed network or large pattern sets. This paper presents a method to optimize the potential memory usage for multiple string or regular expression matching by the idea of combining DFA's paths, named isomorphic path combination (IMPC). To achieve IMPC, a novel multiple pattern matching algorithm is proposed, which is based on Cached DFA (CDFA). Compared to extended AC algorithm based on DFA, our method on CDFA can reduce 78.6% states for Snort pattern set, which results in one of the most memory efficient methods. More important is that our method can be embedded to other algorithms as the optimization.