文件分层-属性基多关键字可搜索加密方案

File Hierarchy Attribute-based Multi-keyword Searchable Encryption Scheme

针对目前的文件分层的基于属性可搜索加密方案存在不支持LSSS访问结构以及多关键字密文较长等问题,提出了一个云环境下灵活高效、支持LSSS访问结构和文件分层的多关键字可搜索方案。首先通过将秘密值分配的方法,将下层的秘密值直接嵌入上层的密文中,不仅缩短了分层加密文件的密文长度,还提高了加密、解密效率;其次通过对多关键字构造索引向量的方式,解决了目前多关键可搜索方案中关键字密文长度随关键字个数线性增加的问题,实现了关键字密文长度固定的多关键字搜索,并采用先关键字搜索,再解密的方式进一步提高了关键字的搜索效率。最后通过将部分解密工作转移到云端,从而降低了用户的计算负担。基于q-parallel BDHE假设下证明了该方案可抵抗选择明文安全攻击(CPA),理论分析和实验结果证明了方案的有效性。

In view of the problems of the current file hierarchy attribute based searchable encryption scheme which does not support LSSS access structure and has long keyword ciphertext,a multi keyword searchable scheme supporting LSSS access structure and file hierarchy in cloud environment is proposed.Firstly,the secret value of the lower layer is directly embedded into the upper layer ciphertext by means of secret sharing,which not only shortens the length of the ciphertext,but also improves the encryption and decryption efficiency of the hierarchical encrypted files.Secondly,by constructing index vector of multi-keywords,it solves the problem that the ciphertext length of keywords in multi-keyword searchable scheme increases linearly with the number of keywords,realizes the fixed ciphertext length of keywords,and keyword search first and then decryption is adopted to further improve the efficiency of keyword search.Finally,by transferring part of the decryption work to the cloud,the computing burden of users is reduced.Based on the assumption of q-parallel BDHE,it is proved that this scheme can resist chosen plaintext attacks(CPA).Theoretical analysis and experimental results show the effectiveness of the scheme.