Sortable Multi-keyword Combination And Extraction Query System Over Encrypted Data

As the cloud is semi-trusted(Faithfully implement the user's operation but curious about the user's data),when the users use the cloud services,they need to encrypt the private data and store it in the form of ciphertext.However,the encryption will destroy the original characteristics of the data.Therefore,it is of great significance to investigate an efficient and safe query system for the combination,extraction and sortaction of multi-keyword.There is a problem that when we use the Asymmetric Scalar-product Preserving Encryption(ASPE)to encrypt the indexes and the queries,this encryption scheme cannot satisfy the non-relevance of the secure index.According to the characteristics that the unilateral invertible matrix has a number of different inverse matrices,this study enhance the security of the data by improve ASPE scheme and make sure that it can satisfy the non-relevance of the secure index.In order to solve the problem in the existing sortable multi-keyword combination and extractiong query schemes that the query time will linearly increase with the increasing of the number of documents,based on the complete binary tree we constructed a secure index tree,which can dynamically update its nodes according to the addition or deletion of the documents.According to the pruning of the intermediate nodes' combination and extraction query and the result sorting,we make the time complexity of the query function is the logarithm of the number of documents and reduce the query time.Therefore,our scheme can better meet the query scenes that there is a lot of documents in the cloud.This study designed a query system based on the improved ASPE scheme and the secure index tree.The correctness and the security were analyzed and experiments verified its correctness and efficiency.The experimental results show that the query system is suitable for the above scene,and this method is more efficient than the schemes without using the secure index tree.Compared with the traditional ASPE shcme,the performance of the improved ASPE scheme has no much compromise.