The Design And Analysis Of Key Distribution Schemes In Wireless Sensor Networks

Wireless Sensor Networks (WSNs) which integrate wireless communication technology, sensing technology and computer technology are considered as one of the most important technologies in the 21th century. WSNs are organized by a large number of micro-sensor nodes which have features like self-organization, low power, low storage capacity, low computation etc, and had been widely used in military, environmental monitoring , medical and health field. Because of the wider application, security becomes more and more important. The key management which provides information encryption and nodes authentication is especially crucial.The main task of this article is analysis of schemes which had been proposed and design the improved pair-wise and group key management schemes which are more suitable for WSNs. It includes the following three parts: First, based on the facts that the LU matrix based pair-wise key scheme has several fatal flaws: uneven distribution of key information, disclosure of U matrix and the fact that size of system has the great impact on efficiency. In order to solve these problems, we propose an improved scheme called random pair-wise key pre-distribution scheme based on LU matrix space, then give the analysis of its security, feasibility and efficiency. Second, after study the polynomial group key scheme which has less computation and simpler agreement procedure, we find that it's not suitable for WSNs for the following reasons: not give the solution to the situation when the size of the polynomial is not the same as the group, cannot meet the requirement of freshness for a relatively stable group's key since the key for a certain group is always the same, don't support members'quit or join and groups'interconnection. However, we can improve it by setting proper parameters and communication protocol. The analysis of the improved polynomial-based group key management for WSNs is also given. Last, there are three basic pair-wise key pre-distribution schemes: randomly assignment scheme, symmetric matrix based scheme and symmetric polynomial based scheme, they all have been widely accepted and used to construct new methods. So we test them in Sun SPOT sensors as to compare their performance. Besides, the test results of several main cryptographical functions on Sun SPOT are also given.