Research On Multicast Key Management Schemes

Multicast key management is crucial in secure multicast. It is significant to reaserch onmulticast key management in order to ensure the security of multicast communication. Forapplication characters of multicast communication in different network circumstances, the thesisseparately researches on centralized, decentralized and distributed multicast key managementschemes. Its main contributions are summarized as follows:1. Research on multicast key management schemes based on characteristic values ofmembers. Firstly, we present a new collusion attack on Pour-like schemes by using the conditionthat each group member stores the inverses of other members’ characteristic values. Secondly,we propose a collusion-resistant centralized multicast key management scheme based oncharacteristic values of members. In the scheme, the remaining group members update keysthrough calculating themselves when a member is joining or leaving, and the communicationoverhead of Group Key Cotroller (GKC) which is the number of transmissions is2andlog2n(n is the number of group members) respectively in case of joining rekeying or leavingrekeying. It achieves forward security and backward security, and resists collusion attack.Compared with equally secure SKDC scheme and LKH scheme, the communication overhead ofGKC is much lower，although the computational overheard of group members is larger. Finally,we design a decentralized multicast key management scheme based on characteristic values ofmembers for the requirements of large secure multicast communication. It solves the problemthat Saroit scheme can not resist collustion attack. Compared with Iolus scheme, computationaloverhead of subgroup members is larger in our scheme, but the number of transmissions ofSub-Group Key controller (SGKC) is decreased from m1tolog2m (m is the number ofsubgroup members).2. Research on multicast key management schemes based on the relationship of members’administrative subordination. For the problem that general decentralized multicast keymanagement scheme was not applicable with multicast circumstance that group members havethe relationship of administrative subordination, we present a decentralized multicast keymanagement scheme based on the relationship of members’ administrative subordination. Thisscheme constructs a members’ hierarchical tree structure based on the relationship ofadministrative subordination. On this basis, it realizes the authentication for part of groupmembers by establishing the up and down layers’ accessing relation through one-way key chain.According to the character of administrative subordination relationship, layer keys and subgroupkeys are updated based on logical key tree structure managing the bottom group keys. It achieves forward security and backward security, and avoids the problem of single node invalidation. Itincreases the storage overhead of GKC and SGKC to make sure secure multicastcommunications in the area of administrative subordination relationship. Their storage overheadis2N1(N represents the number of the bottom groups) and‖T_i‖+2(‖T_i‖represents thenumber of the bottom group members) respectively.3. Research on distributed multicast key management schemes for Ad hoc networks. For theissue that μBD protocol can not achieve group key authentication, we present an authenticatedgroup key agreement protocol based on elliptic curves cryptography (ECC). In the protocol, thestorage of every member is5, and the computational overhead of each group member is7scalarmultiplications and one inverse operation. In addition, the number of broadcast messages is2nin all. Especially when a member is joining, group members need to broadcast5messages andulticast n4messages. When a member is leaving, group members need to broadcast4messages in all. Compared with μBD protocol, the number of negotiation rounds in our protocolkeeps being two. The protocol can not only resist passive attack, but also resist active attackunder the precondition that group members are honest. At the same time, it achives forwardsecurity, backward security and perfect forward secrecy. Compared with equally secure Fengprotocol (The storage of sponsor is3, and other members’ storage is2. In the initialization, thenumber of scalar multiplications is n-1, and the number of broadcast messages is n+1. Whena member is joining or leaving, the number of broadcast messages is n+3and nrespectively), the computational overhead and the number of leaving re-keying messages isindependent of the number of group members, though the storage of a group member and thenumber of broadcast messages in initialization phase is larger.