A secure kNN query processing algorithm using homomorphic encryption on outsourced database

With the adoption of cloud computing, database outsourcing has emerged as a new platform. Due to the serious privacy concerns associated with cloud computing, databases must be encrypted before being outsourced to the cloud. Therefore, various k-nearest neighbor (kNN) query processing techniques have been proposed for encrypted databases. However, existing schemes are either insecure or inefficient. In this paper, we propose a new secure kNN query processing algorithm. Our algorithm guarantees the confidentiality of both encrypted data and users' query records. To achieve a high level of query processing efficiency, we also devise an encrypted index search scheme that performs data filtering without revealing data access patterns. A performance analysis shows that the proposed scheme outperforms the existing scheme in terms of query processing costs while preserving data privacy.