Block chain assisted privacy protection image retrieval method

The invention discloses a blockchain-assisted privacy protection image retrieval method, which comprises the following steps: firstly, an image owner extracts image features by using a CNN model, then encrypts an image and the features by using an SM4 algorithm and a secure kNN algorithm, and uploads a ciphertext image to a cloud server; then, the image owner calculates the hash of the ciphertext image and generates a Merkle hash tree, then an index table of encryption features is constructed by using an LSH algorithm, and the index table and the Merkle tree are uploaded to an alliance chain; and finally, the user uploads the encryption feature of the query image to the alliance chain, retrieves the IDs of the first k images similar to the image, and returns the k IDs to the cloud, the cloud sends the corresponding image to the user, and the user decrypts the image to obtain a plaintext image. The advanced block chain technology and the cryptography technology are adopted, the accuracy of the retrieval result can be guaranteed, and the integrity of the image data stored in the cloud can be verified; meanwhile, the image retrieval problem in the multi-cloud environment is solved, and the efficiency of the retrieval scheme is improved.