Secure k-NN query on encrypted cloud database without key-sharing

In cloud computing, secure analysis on outsourced encrypted data is a significant topic. As a frequently used query for online applications, secure k-nearest neighbours (k-NN) computation on encrypted cloud data has received much attention, and several solutions for it have been put forward. However, most existing schemes assume the query users are fully trusted and all query users know the entire key which is used to encrypt and decrypt data owner’s outsourced database. It is constitutionally not feasible in lots of real-world applications. In this paper, we propose a novel secure and practical scheme for preserving data privacy and supporting k-NN query on encrypted cloud data. In the new approach, only limited information about the key of data owner is disclosed to query users, and the data privacy can be protected even when query users leak their knowledge about the key to adversary. Theoretical analysis and experiment results confirm the security and practicality of our scheme.