Hierarchical State Machine Architecture for Regular Expression Pattern Matching

Regular expression has been widely used in network intrusion detection system to represent attack patterns due to its expressive power and flexibility. However, the traditional memory architecture suffers from the problem of memory explosion for certain types of complex regular expressions. In this paper, we propose a hierarchical state machine architecture which can significantly reduce the memory required to accommodate complex regular expression patterns. The experiments demonstrate a significant reduction in memory for the complex regular expression patterns commonly used in network intrusion detection systems.