云存储中无证书连接关键词密文检索

Certificateless conjunctive keyword search on encrypted data in cloud storage

基于证书的可搜索加密(searchable encryption,SE)方案存在用户公钥验证与证书管理上的缺陷,且多数单关键词搜索的方案会返回大量不相关的密文,而少数采用多关键词搜索的方案需要建立很长的关键词密文索引。本文提出了新的关键词密文检索方案,该方案采用了无证书公钥密码体制,既避免了基于证书的密码体制中的公钥验证和证书管理问题,又解决了基于身份的密码体制中密钥托管问题;方案中采用了连接关键词搜索,多关键词搜索使得密文查找更加精准;本文把访问关键词密文陷门进行了聚合,使得陷门长度简短有效,且通信带宽和存储量得到一定程度上的节约。在随机预言机模型下,证明本文方案可抗离线关键词猜测攻击。

As the certificate-based searchable encryption schemes are required to verify user′s public key and manage certificates, and most single keyword search schemes return a huge volumes of irrelevant ciphertext. And a few multi-keywords searchable schemes have to set up a quite long keywords ciphertext index. Therefore, a newly keyword search over encrypted data scheme using certificateless public key cryptosystem was proposed which can avoid public key verification and certificate management problems based on certificate cryptosystem and eliminate the key escrow problem based on identity cryptosystem. This paper employs conjunctive and multi-keywords search which gets ciphertext search more precise. Moreover, through aggregating keywords trapdoor token makes the token short and effectiv, and further getting a degree of savings in bandwidth and storage. Finally, the security analysis proved that our scheme is secure against off-line keyword guessing attack under a random oracle model.