Nowadays, a user authentication is very important in network environments. For safe authentication, they came up with six essential conditions in earlier studies. And a variety of mechanisms is presented by research scientists. However, they could not achieve the PFS. Because, though all these schemes are assumed that the communication between a smart card and a host is safe, actually it is not. Therefore, in this paper, we will point out what the communication between a smart card and a host is not safe, and propose a new user authentication mechanism that can reach to the PFS. And also, an encryption algorithm is used about 45% less than earlier studies in our proposed scheme. Thus, we can say that enhance the efficiency.

In this paper, we propose an efficient method of constructing states in bottom-up tree pattern matching with dynamic programming technique for optimal code generation. This method can be derived from precomputing the analysis which is needed for constructing states. The proposed scheme is more efficient than other scheme because we can avoid unfruitful tests in constructing states at compile time. Furthermore, the relevant analyses needed for this proposal are largely achieved at compile-compile time, which secures actual efficiency at compile time.