Multi-keyword Searchable Attribute-based Encryption Scheme For Cloud Storage

With the rapid development of Internet information technology and the increasing network bandwidth,more and more users begin to store large amounts of personal data on the cloud servers,but it also brings a lot of problems,such as data privacy and data retrieval issues.By combining the attribute-based encryption mechanism(ABE)with the searchable encryption mechanism(SE),we can not only solve the problem of data privacy under the cloud storage,but also solve the problem of efficient retrieval of massive data.At present,much progress has been made in the field of searchable attribute-based encryption(ABSE),but most of the existing schemes are constructed based on the decisional bilinear pairs,with the development of quantum computing technology,there will be security risks in these schemes.Lattice cryptography has attracted more and more scholars' attention and research due to their anti-quantum attack and efficient operation.This thesis revolves around the theme of the attribute-based encryption with multikeyword searchable under the cloud storage,and constructs the encryption scheme based on the difficult problems of lattice and ideal lattice respectively.The main work is as follows:(1)This thesis proposes a keyword searchable attribute-based encryption scheme based on the difficult problem of LWE on the lattice.In order to better meet the needs of shared access and permission control in the cloud storage environment,the scheme adopts the Key-Policy Attribute-Based Encryption mechanism,and integrate the Public-Key Encryption with Keyword Searchable mechanism to solve the problem of massive ciphertext data retrieval;In addition,the security of the scheme has been improved from the difficult problem of bilinear pairing to the difficult problem of LWE on the lattice,which makes the scheme have the characteristics of resisting quantum attacks,and transform the ordinary lattice matrix into a G-trapdoor matrix,so that it can take up less storage space and calculate the trapdoor faster,so as to improve the overall efficiency of the scheme.(2)This thesis proposes a multi-keyword searchable attribute-based encryption scheme based on the difficult problem of R-LWE on the ideal lattice.By using multiple keywords to improve the accuracy of the search results of the scheme,making it more suitable for the retrieval of massive data in the cloud storage environment;In addition,due to the special algebraic structure and cyclic characteristics of the ideal lattice,this scheme constructs a new searchable attribute-based encryption scheme through the problem of R-LWE,so that the number of keywords and the lattice matrix no longer show a linear growth relationship.Make the solution more advantageous in terms of computing and storage.(3)The two schemes proposed in this thesis are separately made security proof under the random oracle model.As long as the problem of LWE and the problem of R-LWE are difficult to solve,our scheme can satisfy the indistinguishability security against the chosen plaintext attack and the indistinguishability security against the chosen keyword attack.