Chaotic Encryption Technique for Color Images by Coupling Two Chaotic Maps

With the increasing demand of providing security for images/videos with private information, chaos-based cryptosystems have played an important role in image encryption because of their excellent random properties and encryption performance. However, existing chaos-based systems have the security defect due to small key space or other security weakness. This paper introduces an efficient chaosbased stream cipher, composing two chaotic maps (Logistic map and Standard map) and a large enough external secret key for image encryption. The external secret key is used to derive the initial conditions for the chaotic maps, and is employed with the two chaotic maps to confuse the relationship between the cipher image and the plain image. The proposed chaotic system shows excellent chaotic behaviours encryption performance, high sensitivity to the security keys, and a sufficiently large key space to resist the brute attack.