A Feasible Chaotic Encryption Scheme for Image

Cryptography is an important technique to keep private data secretly in order to avoid unauthorized access. Traditional encryption methods such as DES, RSA etc... are widely used today and it seems to be computationally secure. Chaotic encryption is the new direction of cryptography and only few papers discuss on it, and it makes use of chaotic system properties such as sensitive to initial condition and lost of information. An image encryption scheme is proposed, in which shifting the positions and changing the grey values of image pixels are combined simultaneously to ensure a high level of security. Arnold cat map is used to permute the positions of the image pixels in the spatial domain. Then another chaotic logistic map is used to substitute the relationship between the ciphered image and the original image. An external 128 bit secret key is employed and is further modified after encrypting each pixel of the original image to make the encryption more robust against attacks. Sensitivity analysis, key space analysis and statistical analysis of several experimental results indicate the presented scheme has high security and superior quality, and thereby it is feasible.