Biblio

A key exchange protocol is an important primitive in the field of information and network security and is used to exchange a common secret key among various parties. A number of key exchange protocols exist in the literature and most of them are based on the Diffie-Hellman (DH) problem. But, these DH type protocols cannot resist to the modern computing technologies like quantum computing, grid computing etc. Therefore, a more powerful non-DH type key exchange protocol is required which could resist the quantum and exponential attacks. In the year 2013, Lei and Liao, thus proposed a lattice-based key exchange protocol. Their protocol was related to the NTRU-ENCRYPT and NTRU-SIGN and so, was referred as NTRU-KE. In this paper, we identify that NTRU-KE lacks the authentication mechanism and suffers from the man-in-the-middle (MITM) attack. This attack may lead to the forging the authenticated users and exchanging the wrong key.

The consistency checking of network security policy is an important issue of network security field, but current studies lack of overall security strategy modeling and entire network checking. In order to check the consistency of policy in distributed network system, a security policy model is proposed based on network topology, which checks conflicts of security policies for all communication paths in the network. First, the model uniformly describes network devices, domains and links, abstracts the network topology as an undirected graph, and formats the ACL (Access Control List) rules into quintuples. Then, based on the undirected graph, the model searches all possible paths between all domains in the topology, and checks the quintuple consistency by using a classifying algorithm. The experiments in campus network demonstrate that this model can effectively detect the conflicts of policy globally in the distributed network and ensure the consistency of the network security policies.