EnDAS: Efficient Encrypted Data Search as a Mobile Cloud Service

Abstract

Document storage in the cloud infrastructure is rapidly gaining popularity throughout the world. However, it poses risk to consumers unless the data is encrypted for security. Encrypted data should be effectively searchable and retrievable without any privacy leaks, particularly for the mobile client. Although recent research has solved many security issues, the architecture cannot be applied on mobile devices directly under the mobile cloud environment. This is due to the challenges imposed by wireless networks, such as latency sensitivity, poor connectivity, and low transmission rates. This leads to a long search time and extra network traffic costs when using traditional search schemes. This study addresses these issues by proposing an efficient Encrypted Data Search (EnDAS) scheme as a mobile cloud service. This innovative scheme uses a lightweight trapdoor (encrypted keyword) compression method, which optimizes the data communication process by reducing the trapdoor’s size for traffic efficiency. In this study, we also propose two optimization methods for document search, called the Trapdoor Mapping Table (TMT) module and Ranked Serial Binary Search (RSBS) algorithm, to speed the search time. Results show that EnDAS reduces search time by as well as network traffic. The ranked keyword search will return documents to the relevance score. Zero et al. proposed a novel technique that makes the server side carry out the search operation. However, it should send many unrelated documents back and let the user filter them. This is a waste of traffic, which is unsuitable for the mobile cloud. Bowers et all. proposed a distributed cryptographic system that preserved the security of the document retrieval process and the high availability of The system, but this system suffers from two network round trips and calculation complexity for target documents. Wang et al. proposed a    single round trip encrypted search scheme, but their system is not secure enough, as it leaks the keyword and associated document information from multiple keyword searches. Li et al.  proposed a single-keyword encryption search scheme utilizing ranked keyword search, which network communication between the user and the cloud

by transferring the computing burden from the user to the cloud.