Research On Deniable Group Key Agreement Protocol And Their Applications

As a cryptographic primitive,the non-public verification of deniable authentication has broad prospects.Group key agreement protocol as a typical multi-party computation protocol,faced with a series of security problems,such as the collusion attacks.The deniable group key agreement(DGKA)protocol coming from the combination of two ideas is used to establish a confidential channel for communications,simultaneously the DGKA protocol allows the participants of the protocol refuse to recognize that they have ever participated in the session after the end of the agreement.Therefore,the DGKA protocol has broad application prospects in the occasions that the user’s privacy needs to be protected,e.g.financial negotiations on the Internet.The focus of this thesis is to study how to construct secure and efficient DGKA protocol and their applications.The contributions and innovations of this thesis are listed in the following three parts.1.This thesis aims to study how to construct a secure and efficient DGKA protocol.The basic idea is to introduce the deniable authentication to the group key agreement protocol.First,we propose a DGKA protocol by using the zero-knowledge identification scheme based on the unauthenticated DB-GKA protocol.Compared with the existing protocols,our protocol needs only two rounds to get a common key,which means it is more efficient than others as to the communication complexity.At the same time,we had proved our protocol is deniable by constructing a simulator(50)and meets authentication by the forking lemma.2.A deniable authentication protocol for multi-party computation protocol is proposed in this thesis.By analyzing the existing DGKA protocol,we found the deniability depends on the final session key,which greatly limited the development of the deniable authentication.Hence,we will study how to implement the deniable authentication for multi-party computation protocols.Following this idea,we proposed a deniable authentication for multi-party computation by using one string commitment scheme.At the same time,we proposed a security model for our protocol and gave the strict security proof,namely our protocol meets the deniability and robustness.Finally,we tried to apply this protocol to group key agreement and implemented the DGKA protocol.3.A strong privacy-preserving LBS is proposed in VANETs.Vehicular Ad-Hoc Networks(VANETs)are specially designed for communications of vehicles,it provide a great convenience for the vehicles,one of important applications is Location-based Services(LBS).LBS means that vehicles send a series of request related to location to Service Provider(SP)in the process of driving.However,as the cost of enjoying the service,the vehicles face a series of privacy problems,such as the location of the vehicle information is exposed to the base station,illegal base station may maliciously use of the consumer information of vehicles,etc.For solving these problems,we proposed a strong privacy-preserving LBS.The anonymity and deniability of our scheme can effectively protect the privacy of vehicles.Therefore,it has very good practical value.