中文摘要：

基于传统的IRBAC2000模型，对域间角色转换时产生的安全问题进行了分析。提出了一种改进的IRBAC2000模型，该模型将传统模型中的角色分为域内角色和域间管理员角色，为域间角色转换产生的安全性问题提供了一种新的判定方法，提出了先决条件的概念来加强IRBAC2000模型安全性的保护机制。

英文摘要：

Based on traditional IRBC2000 models, the secure issue caused in inter-domain role transformation was analyzed. An improved IRBAC2000 model was presented ,which divided the roles in the traditional model into two types： inside-domain role and inter-domain role; provided a judgment method for the secure issue caused in inter-domain roles transformation and introduced a prerequisite to strengthen the protective mechanism of the security of IRBC2000 model.