Fault-tolerant Verifiable Keyword Symmetric Searchable Encryption in Hybrid Cloud

As cloud computing is increasingly expanding its application scenario, it is vital for cloud storage customers not to sacrifice the confidentiality of sensitive data while making fullest use of operational functionality of cloud secure systems. Although traditional searchable encryption can well solve exact keyword search on encrypted data with retrieving files by search interest, it does not work when typos or misspelling mistakes occur. Many specific algorithms have been well proposed to solve this difficult problem. However, most of the schemes mainly focus on the single cloud to achieve fuzzy keyword search, which means that fuzzy-keyword index construction must take possible typos into account and makes existing exactkeyword index useless. In addition, existing searching schemes rarely take interaction between the data user and the cloud to improve system’s usability and user’s retrieval satisfactory degree into consideration. In this paper, we propose an improved scheme named as Distributed Fault-tolerant Keyword Search Supporting Verifiable Search-ability (DFKSSVS) in hybrid cloud with the emphasis of interaction circumstances. Through improved dictionary-based keyword construction scheme, we generate fuzzy keyword set, and build secure index for efficient fuzzy search. After searching procedures, the scheme can support verifiability of returned files via proof returned by cloud as well, and interaction between data user and private cloud to achieve dynamic ranking of retrieval results statistically. Through rigorous security and thorough analysis, we show that the improved solution can meet verifiable fuzzy keyword search on cloud encrypted data with supporting the exact-keyword index already generated. Security analysis and extensive experimental results demonstrate the accuracy and efficiency of our proposed scheme.