实现数据库细粒度访问控制的一种动态查询修改算法

由于隐私保护和基于W cb的安全需求的驱动，数据库细粒度访问控制引起了研究者的广泛关注。细粒度访问控制主要通过查询改写方法实现。然而，在以往的查询改写算法中，没有考虑用户提交的SQL语句的特性和细粒度访问控制策略的特性，从而导致最终执行的SQL中存在大量的冗余，影响了SQL语句执行的性能。在考虑SQL语句和细粒度访问控制策略的特性的前提下，分析了两类冗余，并给出了相应的移除方法。最终提出了一种用于细粒度访问控制实现的查询改写算法。实验证实该算法具有更好的性能。

Dynamical Query Modification Algorithm for Fine-grained Access Control in Databases

Fine-grained access control has received much attention from research community due to the requirements of privacy preserving and Web-based applications. It is a promising approach to implement fine-grained access control by query modification. However, in the areing query modification algorithm, the features of the queries issued by users and the features of FGAC policy are not considered. Thus,there are redundancies in the final executed queries which make unnecessary overhead. We first analyzed two different redundancies bases on the feature of queries issued by users and the FGAC policies. I}hen, we proposed a technique to detect these redundancies and provided a new algorithm to implement FGAC. A comprehensive set of experiments show that the performance is improved by the proposed algorithm.