多实例的多级安全关系数据库数据模型研究

现有的基于多实例的多级安全数据模型中，存在着语义的二义性问题和更新操作的元组增生问题，增加了系统实现和用户操作的复杂度，也存在着潜在的安全隐患，本文系统地结合多实例和伪元组的概念，以形式简单，易于实现并避免引入隐通道为原则，对上述模型进行了改进，提出了一个新的“同级读，同级写”的多级安全数据模型。

A New Polyinstantiation-based Multilevel Security Relational Data Model

Semantic ambiguity and the problem of increasing tuples brought up by update operation,which exist in current polyinstantiation based data models,complicate much the implementation of system and the operation of users.At the same time,there are potential signaling channel in those data models.So in this article,for the sake of simplicity and avoiding covert channel,we put forward a new multilevel security data model by combining polyinstantiation with the concept of cover story.The new data model allows reading and writing at the same secutiry label with the user.