InstantCryptoGram: Secure Image Retrieval Service

Abstract

Image retrieval is crucial for social media sites such as Instagram to identify similar images and make recommendations for users who share similar interests. To get rid of the storage burden and computation for image retrieval, outsourcing to a remote cloud is now a trend. Yet, privacy concerns mandate the use of encryption before outsourcing the images. We need a secure way for retrieving images from a not-fully-trusted server. This paper proposes InstantCryptoGram, a secure image retrieval service. We first design a new data structure called sub-simhash, which fits for the inverted index used by many searchable symmetric encryption schemes. It leads to our modular solution that supports efficient similarity queries and updates over encrypted images. Our experiments on Amazon AWS EC2 over representative datasets show that our scheme is efficient and accurate in finding similar images while preserving privacy.