부산대학교 도서관

Image encryption is different than text encryption due to image characteristics such as high redundancy of data and bulk data capacity. To handle the difference, new algorithms are being designed. Those image encryption algorithms evolve around shuffling and encrypting. For certain algorithms, a key as large as the image itself needs to be constructed. Chaotic systems are very sensitive to the initial condition which makes it best fit to create a random number generator which is very beneficial in image cryptography applications. In this paper, an algorithm scheme is proposed based on chaotic switching-type oscillator. The paper is divided into two main phases which are shuffling and encrypting using the chaotic key and a different number of predefined iterations. The encryption algorithm is a bitwise linear operator. The key space contains 262144 chaotic values. The initial values of the keystream are very sensitive, changing one of the inputs from 0 to 0.00000001 caused a dramatic change in the keystream and makes it impossible to decrypt the image using the same encryption scheme. The encryption process changed the correlation from 0.9730 in the original image into 0.0330 in the ciphered image.