Digital RGB image encryption based on 2D cat map and shadow numbers

Encryption is one of many methods that have been used to secure storage and transmit images over unsecured and open networks. The asymmetric cryptography need more time for encryption and decryption. In this paper we suggested new method for image encryption that has the potential to overcome many of encryption problems. The proposed algorithm based on the concept of scrambling the positions of pixels, and changing the pixels intensity. The algorithm based on two major steps. The first one is scrambling image with uniform distribution for image data based on two dimension Cat map which improved for more secure by increasing the cycles of processing. While the second step is modifying a method of Shadow process algorithm. This modification makes the Shadow process suitable to work efficiently with images. The modified method uses image as a public key for encryption, and from the public key we derive the decryption key. The performance of proposed algorithm measures and gives high uncorrelated between adjacent pixels in encrypted image, high entropy and mostly uniform distribution, it gives better results compared with other works.