A hierarchical group key agreement protocol using orientable attributes for cloud computing

Group key agreement is one of the key technologies for ensuring information exchange security among group members. Due to different sensitivities of the information, group members may only want to exchange certain secret information under certain circumstances, and also due to different access permissions of member, certain information exchange may aim at different access authorities. Aiming at these requirements, a hierarchical group key agreement protocol using orientable attribute (HGKA-OA) is proposed in this paper. In this protocol, different secret information is shared among a set of members who have different authority levels. Assuming different permission levels correspond to different attributes or their combinations of the terminal, when one people has some secret information he can exchange information with some people who have the appropriate level of security permissions, rather than all the members in the group. The proposed scheme eliminates a majority of the computation task of terminals by moving identity authentication computation to the registration. In addition, the group key factors are also calculated before the group key agreement, which eliminates most of computation overhead due to group key agreement. This protocol is proven secure under the Decisional Bilinear Diffie-Hellman (DBDH) problem assumption and performance analysis shows that the proposed scheme is more efficient than existing works.