The Research Of Image Authentication Technologies In Encryption Domain

Cloud computing and image authentication all are hotspot in academia andengineering community. For some high security requirements data and applications,the cloud environments cannot be trusted; they need to be encrypted for security.However, most existing image authentication algorithms are designed for the plaintextdata, cannot handle encrypted image. Obviously, they do not meet the needs of theseapplications. Homomorphic-based image authentication is an important researchdirection to solve this problem, has great value in theory and practical significance. Inthis paper, we first do in-depth study and research of related technologies of imageauthentication and encryption, and then carry out preliminary exploration of imageauthentication in encrypted domain by homomorphic encryption technology.Following are our works:(1)A novel image encryption algorithm based on chaos and line map is proposed.The algorithm is based on the "Scrambling-diffusion" architecture. It has a uniquepermutation process, the simplicity of line map and the random of chaos had beencombined to do bit level image scrambling. Besides, the influence between thetrue-color image’s three color components had been considered fully. All these lead toa completely confusing. Experiments showed that the image encryption algorithm issatisfactory, can effectively resist brute-force attack, statistical analysis anddifferential analysis attacks, etc.(2)Paillier-based image homomorphic encryption algorithm has beenimplemented. After a full understanding of the image encryption technologies, thisarticle based on random half homomorphic encryption algorithm Paillier achievedimage homomorphic encryption. To illustrate the feasibility of the scheme, accordingto the relevant needs of the digital image encryption, the scheme, the general imageencryption algorithm and RSA encryption algorithm were compared. Theoreticalanalysis and experiments showed that the Paillier algorithm is capable of imageencryption.(3)The method to calculate image’s Zernike moments in cipher-text domain hasbeen proposed. The method can calculate Zernike moments of image without privatekey in encrypted domain by breaking apart formula into components. Experiments showed that Zernike moments calculated by the method has minimal loss of accuracy,can meet the various needs of Zernike-related applications in encrypted domain.In this paper,Around the theme of image authentication in encrypted domain, wefirst proposed a new image encryption algorithm, experiments showed that thealgorithm is efficient, safe, has a certain practicality; then, Paillier-based imagehomomorphic encryption algorithm has been implemented. At last, the method tocalculate image’s Zernike moments in cipher-text domain has been proposed; It laythe foundation for the design of related applications. I believe our works willcontribute to the further development of homomorphic encryption technology, imageencryption technology and homomorphic-based image authentication technology.