Colour image encryption based on multiple fractional order chaotic systems

This paper demonstrates a colour image encryption algorithm that incorporates multiple fractional order chaotic systems. Here, the fractional order extensions of four well known chaotic systems are tactfully combined together to generate the cyphering key. The encrypted image shows uniform histogram, zero autocorrelation and very high entropy for all the three colour-channels. Moreover, the algorithm possesses an extremely huge key-space. Thus, the algorithm becomes invulnerable against brute-force attacks. However, due to the fact that the fractional order derivatives are not `local operations´ like their integer order counterparts, solving fractional order differential equations become a difficult and time consuming task for computers. To overcome this, some efficient computing techniques have been adopted to run the encryption-decryption process reasonably fast.