Abstract: For the purpose of economic saving as well as to achieve flexibility users outsourced their data on public cloud. Before storing data on cloud user wish to apply some security constraints to protect their data form malicious attacks. Therefore they used to refer encryption technique to encode their data and then they will outsource it. Existing systems which refers encryption technique are inefficient as they are having only single keyword search over large document. To the best solution for this inefficiency we proposed multikeyword search strategy for large number of documents. Our multikeyword search technique is efficiently word against the searching of multiple keywords simultaneously. It may be referred as lightweight process of searching. In our system we used two protocols to generate a secret key dynamically as well as for vali user authentication. Our system effectively works for large amount of databases and multiple keyword searching. In our system we provide higher privacy requirements to implement the data security for cloud stored data. Our main contribution in this project is to give backup and restore facility at the user end and mainly we focused on multikeyword searching with ranking approach.

Keywords: ranked keyword search, multiple owners, privacy preserving, dynamic secret key.