Encryption And Search Of Images And Text For Cloud Environments

With the development of Internet technology and the rise of cloud computing,more and more users choose to store information on third-party cloud storage platforms.This contains a lot of information such as images,texts,and so on.It is well known that these images and texts often contain the privacy of users.The storage of private image and text information on a completely untrusted third-party cloud platform undoubtedly increases the risk of user privacy disclosure.In order to protect the user's image and text information from being leaked and tampered in data transmission process,it is often necessary to encrypt the image and text before uploading it to the cloud server.Most of the current search schemes do not support ciphertext search,so the encrypted image and text need to be decrypted before the corresponding search on the cloud platform,but this increases the risk of revealing privacy.Therefore,the search algorithm for studying encrypted images and texts is of great significance.In view of the above situation,this paper mainly carries out the following research:(1)The image encryption algorithm based on FFT,DCT and chaotic sequence is studied.The frequency domain space of the image is obtained by FFT and DCT.It is robust,coupled with the security of the key of the chaotic sequence to ensure that the algorithm is safe and reliable,and then the experiment is used to analysis and verify algorithm.And the efficiency of encryption,decryption and search between the two methods is compared.(2)The feature extraction algorithm of image based on FFT is studied,and the image feature library is built.At the same time,the ciphertext encryption and decryption algorithm based on homomorphic encryption is studied,and the feature vector in the image feature database is encrypted by the homomorphic encryption algorithm.According to the needs of this paper,the encryption method of the feature vector is based on byte encryption.In addition,in the process of encrypting feature vectors,this paper introduces multi-threading technology,which makes the encryption rate greatly improved.(3)Combining the image encryption algorithm in(1)and the image encryption vector encryption method based on byte encryption proposed in(2),a ciphertextimage search algorithm and a text text search algorithm are proposed.The ciphertext image is searched by the binary search and the unbalanced search method respectively,and the search efficiency is improved compared with other search methods.Moreover,unbalanced search can well ensure that the ordering of ciphertext images is not known by attackers.(4)Finally,this paper designs a storage and search system for encrypted images and texts in the cloud environment,which realizes the functions of encrypted uploading,storing,authorizing and searching of images and text data.