Voronoi-based Secure kNN Queries over Spatial Data at the Cloud

The evolution of cloud computing complete security of the database but does not provide real-time enabled organizations to utilize massive storage and computing power. The main problem with database outsourcing is data confidentiality. To protect the confidentiality of data objects, the data owner encrypts data objects using a strong encryption algorithm, like AES, before sending them to the cloud. Which in turn results in the challenge of searching encrypted data to answer kNN queries. This paper provides a novel solution for answering k NN queries at the cloud over encrypted data. To achieve that, data objects are organized using Voronoi network. Moreover, a Grid-based index is built on top of a Voronoi network to expedite the search for the k NN. The cloud service provider uses the proposed index to extract a superset of the nearest neighboring objects (candidate set) and sends it back to the user. Consequently, the user, which has a copy of the encryption key, decrypts the candidate set and performs the final refinement filter to extract the exact k objects.