A Cryptograph Domain Image Retrieval Method Based On Paillier Homomorphic Block Encryption

With the rapid development of information network, the computing resources and storage capacity of ordinary users can’t meet their needs of data processing. The emergence of cloud computing solves this problem but brings data security problems. How to manage and retrieve ciphertext data effectively becomes a challenging problem. To these problems, a new image retrieval method in ciphertext domain by block image encrypting based on Paillier homomophic cryptosystem is proposed in this paper. Which can be described as follows: The image owner uploads the encrypted original image and the public key to the third party server. The servers store the secret image and extract the image feature using the public key (difference histogram) and build the feature index. The user sends the retrieve image to the server. The server calculates the difference histogram of the retrieved image, retrieves the similar secret image by the feature index, and sends the similar secret image to the user. The user and the image owner verify the identity. Then the user can get the private key, decrypt the secret image with the private key, and get the target image. The experimental results show that the method is feasible and simple.