Abstract: Cloud computing is generating lot of interest to provide solution for data outsourcing and high quality data services. More and more institution, organizations and corporations are exploring the possibility of having their applications, data and their IT assets in cloud. As the data and there by the cloud’s size increases searching of the relevant data is expected to be a challenge. To overcome this challenge, search index is created to aid in faster search. However, search Index creation and computation has been complex and time consuming, leading to cloud-down time there by hindering the swiftness in reacting to data request for mission critical requirements.

Focus of this paper is to explain how in the proposed system, reusability of search index is helping to reduce the complexity of search index computation. Search index is proposed to be created using parameters like similarity relevance, user ranking and scheme robustness. User ranking helps to guarantee why a phrase or a sentence or a key word is used frequently in the uploaded data. The proposed system ensures that the reusability of search index concept, highly reduces cloud down time while maintaining the security using searchable symmetric encryption (SSE).The user requested file is retrieved from the cloud, using Two-round searchable encryption (TRSE) scheme that supports top-k multi-keyword retrieval.

Keywords: Cloud, data privacy, search index, ranking, homomorphic encryption