Secure image retrieval method based on homomorphic encryption

The invention relates to a secure image retrieval method based on homomorphic encryption. The secure image retrieval method includes: firstly, extracting features, such as colors, textures, shapes and the like and reducing dimensions of the image features by a LPP method; secondly, protecting the image features by a Paillier homomorphic encryption algorithm; thirdly, conducting similarity matching of the image features which are encrypted and sending back retrieval results of K images with highest similarity to users. The secure image retrieval method is based on a CBIR structure and adopts a homomorphic encryption technology, so decryption is not needed and direct similarity measurement of the image features which are encrypted can be realized by using by using the homomorphic features of the Paillier encryption algorithm. Accordingly, the problem that the direct retrieval of the image features which are encrypted cannot be realized by the prior retrieval method can be solved. Experiment results prove that the retrieval results of the secure image retrieval method is consistent with the retrieval results of a plaintext CBIR method in the prior art under the condition of ensuring the security of image information, so that the encryption cannot influence the image retrieval performance.