A Symmetric Image Encryption Scheme Using Chaotic Baker Map and Lorenz System

Chaos-based image encryption techniques have recently been extensively studied due to their superior properties in efficiency. However, many of the proposed schemes suffer from known/chosen plaintext attacks as the key stream used in diffusion stage is usually solely determined by the key. This paper suggests a chaos-based symmetric image cipher with a plaintext-related key stream generation mechanism. In the diffusion stage, the state variables of Lorenz system are selected according to the plain pixel. As a result, the quantified key stream is related to both the key and the plain image, which makes known/chosen plaintext attack practically infeasible. Moreover, compared with 1D chaotic maps that commonly employed in existing ciphers, the Lorenz system has more complicated dynamical property and number of state variables, which further enhance the security of the cryptosystem. Thorough security tests are carried out with detailed analysis, demonstrating the high security of the new scheme.