The Research Of Asymmetric Group Key Agreement From Short Signatures And Its Application

Group key agreement protocol enables communicating parties to establish a secure channel over an open and insecure communication channel.Group key agreement protocols can be divided into traditional group key agreement protocols and asymmetric group key agreement protocols.The traditional group key agreement protocols negotiate a common session key that is used for both encryption and decryption,and these protocols currently have problems such as sender restriction and round-inefficiency.Asymmetric group key agreement protocols require only one round of communication and the result of the agreement is a publicly shared group encryption key and a mutually independent group decryption key for each user.These protocols currently suffer from high computation and communication overheads.To address this problem,we propose an efficient and secure asymmetric group key agreement protocol.Currently,most of the traditional broadcast encryption schemes rely on trusted key distributors and do not have forward security or are costly to achieve forward security.To address this problem,we proposes a broadcast encryption scheme based on an asymmetric group key agreement protocol.The specific work of this paper are as follows:1.To address the problems of sender restriction and round-inefficiency in existing traditional group key agreement protocols and the problems of high computation and communication overhead in asymmetric group key agreement protocols,We propose an efficient and secure asymmetric group key agreement protocol based on short signature.The details are as follows:·Multiple users can establish a public group encryption key and a mutually independent group decryption key for each user in one round.Any user can use the group encryption key to send messages to users in the group,solving the problem of sender-restriction.·The protocol is proved to satisfy confidentiality and known-key security under the random oracle model,and its security is reduced to the k-BDHE problem.·Compared to existing asymmetric group key agreement protocols,this protocol has lower computational and communication overheads.·The efficiency of our protocol is evaluated by simulation in a Linux environment using Python and the PYPBC cryptography library.2.We propose a broadcast encryption scheme with conditional forward security based on the above asymmetric group key agreement protocol.The details are as follows:·The scheme does not rely on a trusted key distributor,which solves the single point of failure problem.·In our scheme,group users’ join and exit need only one round of communication and with low computational and communication overhead.·The scheme solves the receiver restriction problem faced by asymmetric group key agreement.The message sender can choose any set of group users as the receiver.·The scheme inherits the security of the above asymmetric group key agreement protocol and satisfies the conditional forward security.The scheme has forward security when the group in the broadcast encryption scheme is a static group.·Compared with existing broadcast encryption schemes based on asymmetric group key agreement protocols,our scheme has lower computational and communication overheads.·The efficiency of our scheme is evaluated by simulation in a Linux environment using Python and the PYPBC cryptography library.