Image Feature Extraction with Homomorphic Encryption on Integer Vector

With the amount of user-contributed image data increasing, it is a potential threat for users that everyone may have the access to gain privacy information. To reduce the possibility of the loss of real information, this paper combines homomorphic encryption scheme and image feature extraction to provide a guarantee for users' privacy. In this paper, the whole system model mainly consists of three parts, including social network service providers (SP), the Interested party (IP) and the applications. Except for the image preprocessing phase, the main operations of feature extraction are conducted in ciphertext domain, which means only SP has the access to the privacy of the users. The extraction algorithm is used to obtain a multi-dimensional histogram descriptor as image feature for each image. As a result, the histogram descriptor can be extracted correctly in encrypted domain in an acceptable time. Besides, the extracted feature can represent the image effectively because of relatively high accuracy. Additionally, many different applications can be conducted by using the encrypted features because of the support of our encryption scheme.