Author : Cheng-Hung Lin , Shih-Chieh Chang
Publisher ： Very Large Scale Integration (VLSI) Systems,
IEEE Transactions on
 In order to accommodate the increasing number of
attack patterns and meet the throughput requirement
of networks, a successful network intrusion detection
system must have a memory-efficient patternmatching algorithm and hardware design.
 This paper presented a memory-efficient pattern
matching algorithm which can significantly reduce the
number of states and transitions by merging pseudoequivalent states while maintaining correctness of
string matching. In addition, the new algorithm is
complementary to other memory reduction
approaches and provides further reductions in
memory needs.
 更改 match vector 成 pathVec 與 ifFinal ,
 define similar states as pseudo-equivalent states
 (have identical input transitions , failure transitions,
and ifFinal bit , but different next states.)
 Add a register, called
preReg
 Example
 two patterns, “abcdefghijklm” and “abcwsghidefxyklm.”
 label the substrings “abc”, “def”, “ghi”, and “klm” as
“α” ”β” ”γ” ”δ”
 Pattern become” αβγjδ” and “αwsγβxyδ”
 Longest common subsecquence between two patterns
are “ α β δ ” or ” α γ δ ”
 Calculate largest sharing gain