The paper introduces a role and permission based delegation model with open and distributed property for PMI,as well as an extended PMI system based on delegation certificate EPMI(extension PMI).

• 该文提出了一种面向PMI环境基于角色和权限两级的开放分布式委托授权模型??DM for PMI(Delegation Model for PMI),并在该模型的基础上引入委托证书,给出了一种扩展的PMI体系架构??EPMI(Extension PMI)。