A stream cipher method for RGB image encryption using PSO base key generation

This paper introduces a novel approach based on a stream cipher to encrypt RGB images. In this regard, a Particle Swarm Optimization (PSO) based algorithm is used to generate the keystream for encryption. Red, green and blue channels of the RGB image are shown as texts and then a stream cipher is used to encrypt the resultant image. A method named PSO Key Generation Color image Encryption (PKGCE) algorithm uses 3 character code tables for each of the 3 channels of RGB image in order to encode the keys and the plain texts showing correspondent channel of the RGB image. A zigzag operation is done on the resultant image in each of the channels to provide more security in a way that the start point of the zigzag path is dependent on the key and channel size. The main advantages of this algorithm over the previously ones, are less number of keys needed to be stored and distributed and also the appropriate speed of the algorithm. Experimental results and the comparison of the proposed algorithm with other encryption algorithms are discussed in detail.