A NOVEL ELLIPTIC CURVE METHOD FOR SECURE MULTICAST SYSTEM

Jyh-Horng Wen (Taiwan), Ming-Chang Wu (Taiwan) and Tzer-Shyong Chen (Taiwan)

Received October 13, 2007

Abstract

In the secure multicast systems, many grouping rekeying schemes are presented to promote the system security and performance. The secure filter method is a reasonable solution presented in the previous study. In the scheme, the secure filter is obtained by operating the hash function with all members’ secret keys. The method requires less system resources to change the legitimate members. However, the conspiring problem is its main weakness. Therefore, we propose an elliptic curve group rekeying scheme to overcome the weakness. In the proposed scheme, the system is divided to subgroups and the corresponding subgroup keys are used in the scheme in addition to the group key. The sub-elliptic curve filter (SECF) is constructed for each subgroup to cover the subgroup key. A main-elliptic curve filter (MECF) is constructed by all the subgroup keys to cover the group key. Since an extra virtual key is designed to add into each SECF and the MECF, the conspiring problem could be overcome in the design. In addition, the time complexity of our proposed scheme is compared with that of the secure filter method. The results show that the computation complexity of our proposed scheme is less than that of secure filter when a member joins or departs in the corresponding subgroup.

Keywords and phrases: multicasting, group elliptic curve filter, access control, secure filter, group key.