Secured Permutation and Substitution Based Image Encryption Algorithm for Medical Security Applications

摘要

Privacy is a vital issue in transmitting or getting the advanced pictures over people in general systems. Picture encryption is a superior answer for accomplish a high security. In recent years, quantities of strategies have been proposed in the writing for picture encryption. The restriction of conventional cipher methods is insecurity upon known plain image attack and their development of the picture is not delicate to changes in plain picture. We proposed an efficient Secured Asymmetric Image Cipher (SAIC) Algorithm in which a secret key of variable size is used. Initially, two different keys are generated by using KG algorithm. One key is utilized for encryption and another is utilized for unscrambling process. By using the encryption key, the original image is scrambled by mixing process. The partially encrypted picture is isolated into element squares and the pieces are further prepared by key dependent permutation and substitution process to get the resultant encrypted image. The decrypted picture is gotten by processing the encrypted image through inverse substitution, inverse permutation and inverse mixing process using the decryption key. Experimental result shows that original image is independent than the encrypted image (NPCR > 99.99%, UACI > 36.7%, DR > 97%). The proposed method is easy to execute, computationally secure and has high encryption rate. Reproduction results accept the secured elements and viability of the proposed framework.