Study On Self-organized Public Key Management In Mobile Ad Hoc Networks

A mobile Ad Hoc network(MANET) is a new special type of wireless network.It has wide application prospect without the need of previous fixed infrastructure,which brings about flexibility as well as new secure issues.It needs some new security schemes and policies for its dynamic network topology,limited bandwidth and deficient terminal power.Cryptography is an internal assumption for most of security services,and key management is the core for its implementation.Requiring no heavy infrastructure and complex bootstrapping,self-organized public key management has become a potential candidate for key management in MANET.However,most of existing schemes have a long warm-up period,low authentication success rate and poor scalability.It is necessary to study its special requirements and propose an efficient self-organized public key management scheme suitable for MANET.This thesis studies self-organized public key management in MANET and two important factors influencing its efficiency:small world characters of certificate graph and public key authentication metric in MANET.Some schemes are provided in this thesis to resolve the issues.The research work of this thesis is supported by National Natural Science Foundation of China(No.60572035) and Beijing Municipality Key Laboratory of Communication and Information System(No.JD100040513).The main innovations of the thesis are as follows:1.A new cloud-based discrete metric trust management model is proposed for the hierarchical trust metric.According to the limitation of the reasoning mechanism of the existing cloud-based discrete metric trust model,base-cloud and accept factor are introduced to unite the trust degree with its uncertainty and solve the problem of fuzziness and randomicity in description and reasoning of trust relationship.The reasoning mechanism of trust cloud can deal with the trust recommendation and synthesis of multiple trust paths,and implement the propagation of trust relationship.The simulation results show that the proposed model can lead to higher cooperation successful rate comparing to the previous models.2.A new cloud-based continuous metric trust management model is proposed for some application in which data source of trust relationship are processed in continuous metric.The model gives new definition of trust cloud and its computing approach.Considering the weight of trust cloud,a series of trust cloud operations are designed to implement the trust recommendation and trust propagation. Simulation results show that the proposed trust model can evaluate the trust relationships among nodes and detect malicious nodes effectively.3.A route-aware trust path searching approach is proposed.It uses local trust and route information to reduce path searching range and communication overhead.4.A new approach is proposed to create small world certificate graph based on clustering.The certificate graph emerges apparent small world phenomenon by signing a few certificates among cluster heads,which increases the efficiency of exchanging and collecting certificates.Simulation results show that the proposed small world certificate graph can reduce the warm-up period and increase the authentication success rate to about 80%which is higher than previous schemes'5.An enhanced self-organized public key management scheme is proposed which depends on local information exchange in building certificate repository.In the scheme,the small world property and trust model are utilized in the operations, such as certificate issue,certificate maintenance and key authentication.Analysis and simulation results show that the enhanced scheme increases the reliability of authentication,reduces the communication overhead and complexity in building local certificate repository,and has well scalability.The research work on self-organized public key management in Ad Hoc networks will be further on with the extension of its application.