中文摘要：

针对垂直划分多决策表，利用半可信第三方和交换加密体制，设计了一个安全多方计算交集基数协议。利用该协议设计了安全多方计算信息熵和安全多方计算条件信息熵的解决方案，提出了一种基于条件信息熵的隐私保护属性约简算法。该算法基于粗糙集信息观的约简理论实现了分布式环境下全局属性约简的求解，使各参与方在不共享其隐私信息的前提下达到集中式属性约简的效果。分析结果表明该算法是有效可行的。

英文摘要：

A privacy-preserving set intersection cardinality computation protocol based on a semi-trusted third party and commutative encryption is developed, which can be used to solve privacy-preserving computational problems, such as information entropy computation and conditional information entropy computation. A privacy-preserving attribute reduction algorithm based on conditional information entropy for the vertically partitioned multi-decision tables is proposed. The algorithm can globally compute the valid attribute reduction using the attribute reduction idea based on the information viewpoint of Rough set theory, which can get accurate attribute reduction effect on the premise of no sharing of private information among participators. Analysis results show the proposed algorithm is efficient.