Research On Key Management In Wireless Sensor Networks

With the development of wireless sensor networks, it is more and more important to design effective security mechanisms. Because sensor networks often transmit sensitive data and are deployed in hostile unattended environments, the security solutions should be taken into account at the beginning of the system design. However, the limited resource makes sensor networks facing with greater challenges than tranditional network. At the same time, the situation also provides vast capabilities and potentials in the research of wireless sensor network security.There are many solutions to provide security service for wireless sensor networks. The solutions based on symmetry cryptography are often very complex in key management, and require a lot of memory to store keys. The solutions based on traditional public key cryptography can provide perfect key management service, but need the trusted third party for authentication. The secure multi-party computation need not require the third trusted party, but it costs lots of computational overhead and communication overhead. In a word, perfect solutions are absent to resolve the security problem that suitable for wireless sensor networks. It is an important research subject to achieve secure and efficient key management in wireless sensor networks.To gain the scientific key selection in wireless sensor networks, based on the deep analysis of the relationship among plaintext size, ciphertext size, key size and the key probability of perfect secrecy of cryptosystem, two necessary conditions for special perfect secrecy cryptosystem are presented and proved. This paper suggests an approach to build perfect secrecy cryptosystem and four criterions for symmetric key selection. By researching a question about the existence of a sort of special perfect secrecy cryptosystem which has not been solved, this paper gives the conclusion and correlative proof. Furthermore, this paper gets a group of relationship of parameters among plaintext size, ciphertext size, and key size, and proves that perfect secrecy cryptosystem can not be built in this way. The results contract the conditions to build perfect secrecy cryptosystem and develop communication theory of Shannon's secrecy system and are helpful for designing secure cryptosystem. The research can help wireless sensor networks to select the symmetric key scientifically and design perfect secrecy cryptosystem.For the disadanvtage of resource limitation in wireless sensor networks, a very efficient identity-based encryption (L-IBE) based on the combined public key scheme is proposed. And in contrast with the existing well-known IBE schemes, the L-IBE scheme has less time complexity, shorter ciphertext and key length. In addition, with the respect of provability security of L-IBE scheme, this new scheme is also better than these existing schemes on provability security in three aspects that are the model, the hardness assumption and the degree of security reduction. Concequetly, it shows that L-IBE is more suitable for the key establishment in wireless sensor networks.Key distribution is one of the most challenging security problems in wireless sensor networks, and the traditional security techniques used in tradition networks cannot be applied directly. We propose an authentication protocol based on identity as the security scheme, which can achieve the key establishment and security authentication. The security of the authentication protocol is analyzed based on BAN logic. The simulation shows the wireless sensor networks can afford the energy consumption in the protocol.A dynamic multiple cluster key management model based on identity is designed in wireless sensor network. The key management in the model is cluster-based and can resist collusion attack. The model can realize the identity authentication independent of the third party, thus no use for infrastructure to sustain the key distribution center. The model consumes a little storage space because every sensor node in the model is just required to store its own private key and the public key factor matrix of the cluster that it belongs to. A secure data aggregation solution based on the model is proposed. The communication process is described and the security of the proposed solution is validated by formal method. The energy consumption during the handshaking process is discussed, which indicates that it is feasible to use the identity-based cryptography in the wireless sensor networks. The simulation shows that, compared with two other typical data aggregation schemes TAG and CPDA, the proposed solution has preferable security, reasonable communication consumption and desirable success ratio.