关键词: 动态加入, 对称多项式, 可信第三方, 组密钥协商, 秘密共享

Abstract: The paper proposes a group key agreement scheme based on [(t,n)] secret sharing. The scheme needs not to secure the communication channel between users in the group in advance by symmetric polynomials. Each user constructs a Component with the share to evaluate and verify the group key. Moreover, the scheme enables a new user to negotiate a new group key with original group users by secret sharing without online Trusted Third Party（TTP）, and thus allows the new user to join the existing group. It has the low computational cost in multicast and multi-hop communication due to the use of group key in communication encryption. Compared with traditional group key agreement scheme, the scheme is able to resist the coalition of up to [t-1] internal attackers without online TTP, eliminates the dependence of pre-existing secure channels between users, and allows a new user to join the group dynamically. Thus, the proposed scheme is more secure and flexible.

Key words: dynamically join, symmetric polynomials, Trusted Third Party（TTP）, group key agreement, secret sharing