Abstract: User has to execute the restricted query while XML document with the sensitive information is in the process of transmission or exchange in Internet，it is always the research topic about how to enhance query efficiency and protect the security of sensitive information.Based on the instance information tree with access control policies，extracting the main information’s policies，reversing to act on the instance information tree and saving the special node policy，this method with compacted policies provides important basis for secure and efficient XML keywords query，in addition，it adopts the extensible Dewey coding which makes the query easy.The experimental results show that the algorithms can lighten the burden of storage and improve the efficiency.

Key words: XML document, extensible Dewey code, keyword search, compression, security

摘要： 当含有敏感信息的XML文档在网络上传输或交换时，需要用户执行受限查询，如何提高查询效率，同时又保证敏感信息的安全一直是安全领域的研究热点。以带访问权限的实例信息树为主体，优先抽取主干信息策略，再反向作用于实例信息树存储特殊节点的压缩方法，为安全且高效的XML关键字查询奠定了基础，而且采用扩展的Dewey编码方式，为安全查询提供了方便。实验结果表明，这种基于压缩策略的安全查询方式减轻了存储负担，提高了查询效率。

关键词: XML文档, 扩展的Dewey编码, 关键字查询, 压缩, 安全