【摘要】 研究了群组通信中的密钥协商协议，首先用可变的底数来代替DH方案中的固定底数，改进了两方(Two-party)密钥协商协议PPK[5]，然后把两方协议扩展成多方（Multi-party）协议，并且分析了所提出的两个协议对被动攻击和主动攻击的抵抗能力，最后给出了前者在抵抗联合攻击方面的不足。更多还原

【Abstract】 Key agreement protocols used in group communication applications are studied. Firstly, the fixed base used in DH schemes is replaced with a changeable base, by which the two-party key agreement protocol PPK[5] is improved. Secondly, the two-party protocol is extended to a multi-party protocol. The security of the two protocols against passive attacks and active attacks is discussed. However, the multi-party protocol can not fight against collusive attacks.更多还原