Several New Pair-wise Keys Distribution Algorithms For Wireless Sensor Networks

Wireless sensor networks (WSNs) are self-organizing networks with a large number of sensornodes. WSNs are open networks, so their securities are very important. The data safe transfer isinevitably involved in both the encryption and the decryption which make key managementcrucially to the security of WSNs. Due to the limited computation, storage space and energy in thesensor nodes, the traditional key distribution and management schemes can not be directly wellapplied in WSNs.In this dissertation, key management schemes based on deployment knowledge areinvestigated. The main work is summarized as follows:(1) An enhanced key distribution scheme EGK which is based on the grid model is proposed.On the basis of Du scheme, the construction of sub-key pools in this scheme has been improvedwhich increases the probability of the local connectivity. At the same time, our scheme uses hashfunctions to protect the key information stored in the nodes and make the securities of the linksincreased approximately 100%.(2) An improved scheme KPDK based on dual-key pools is presented for pair-keysestablishment by using the deployment knowledge and the cellular model. Each sub-key pool in thescheme contains two types of key pools: One doubled by offline server (using hash function) isshared by 3 adjacent cellular before deployment; the other distributed to each cellular isnon-overlapping. The improved construction of sub-key pools can increase local connectivity.Meanwhile, server distributes four random numbers for each cellular and ensures any adjacentcellular sharing one random number. In order to improve the security of the networks, nodes amongneighboring cells adopt hash functions and corresponding random numbers to generate pair-wisekeys.(3) By using Blom matrices, symmetric polynomial thresholds in prime fields and theirreversibility of hash chains, KD-DK scheme based on hexagon is put forward. Before pair-wisekeys to be established, the distributed hash chain values are used to construct a number of Blommatrices whose numbers are less than their thresholds. We use these matrices to generate pair-wisekeys among the nodes in the same region. When the neighboring nodes are in the different regions,the polynomials constructed by randomly pre-distributed keys are employed to establish pair-wisekeys. These designs make the security of the proposed key distribution scheme greatly improvedand make enemies harder to break the networks.(4) To achieve the higher local connectivity and the safer links in wireless sensor networks, a square-based scheme BDKH is presented by using the deployment knowledge and the hash chains.Before the nodes to be deployed, the offline server constructs a number of hash chains andensures using values from a pair of reverse hash chains to establish pair-wise keys among the nodesin the same region. While among the neighboring nodes in the different regions, a pair of hashchains with deployment-related are employed to establish pair-wise keys. These designs makeenemies harder to break the networks and ensure the probability of pair-wise keys establishmentreach 100%.