VFIRM: Verifiable Fine-Grained Encrypted Image Retrieval in Multi-Owner Multi-User Settings

To ensure the security of images outsourced to the malicious cloud without affecting searchability on such outsourced (typically encrypted) images, one could use privacy-preserving Content-Based Image Retrieval (CBIR) primitive. However, conventional privacy-preserving CBIR schemes based on Searchable Symmetric Encryption (SSE) are not capable of supporting efficient fine-grained access control and result verification simultaneously. Therefore, in this article, we propose a Verifiable Fine-grained encrypted Image Retrieval scheme in the Multi-owner multi-user settings (VFIRM). VFIRM first utilizes a novel polynomial-based access strategy to provide efficient fine-grained access control. Then, it employs the dual secure $k$-nearest neighbor technique to distribute distinct keys to different data owners and data users, and finally implements an adapted homomorphic MAC technique to check the correctness of search results. Our formal security analysis shows that VFIRM is non-adaptive semantic secure if the client's search key is generated randomly and keeps in secret. Our empirical experiments using two real-world datasets (i.e., Caltech101 and Corel5k) demonstrate the practicality of VFIRM.

1 Introduction

With increasingly emerging devices (e.g., Android and iOS devices, and Internet of Things devices), a large amount of images are produced, which inevitably brings heavy computation and storage burden locally. There is a corresponding trend for users to outsource their images to the cloud for costs saving and flexibility. In such applications, Content-Based Image Retrieval (CBIR1.

CBIR mainly focuses on extracting visual features, such as colors, textures, and shapes.

) techniques [1], [2] are widely used by commercial Cloud Service Providers (CSPs) (e.g., Flicker, Facebook, and Amazon Cloud Drive) to improve image retrieval efficiency. To ensure image security, users encrypt the images prior to outsourcing. This, however, negates the use of conventional CBIR solutions since such approaches are not effective on encrypted images. Hence, a number of privacy-preserving CBIR schemes [3], [4], [5], [6] based on Symmetric Searchable Encryption (SSE) have been proposed to strike a balance between searchability and confidentiality.