A novel image encryption scheme based on an improper fractional-order chaotic system

Based on the features of digital image encryption and high-dimensional chaotic sequences, the paper proposes a symmetric digital image encryption algorithm by a new improper fractional-order chaotic system. The initial conditions, parameters and fractional orders of chaos are influenced by gray value of all pixels and used as secret key. Therefore, the total key length is large enough to resist any brute-force attacks. The original image is divided into four parts and encrypted by different encryption formulas. Theoretical analysis results show that the proposed encryption scheme has effective encryption and efficiencies.