Real-time image encryption algorithm based on combined chaotic map and optimized lifting wavelet transform

With the development of multimedia technology, the security of image information becomes more and more important. Encryption is a way to protect image information. Chaotic systems are often combined with other algorithms to encrypt images because of their cryptographic properties such as initial value sensitivity and randomness. At present, the common image encryption systems are combined with the traditional scrambling diffusion algorithm, but the number of rounds of scrambling diffusion affects the security and real-time performance at the same time, which makes it impossible to have both. The lifting wavelet transform algorithm is simple, occupies less memory and has high execution efficiency. Based on this, this paper proposes a real-time image encryption algorithm based on a combined chaotic map and optimized lifting wavelet transform to improve the security and efficiency of the system. Instead of using a conventional chaotic system, we propose a new combined chaotic map, which has better randomness and more complex chaotic behavior than a one-dimensional seeded chaotic map. And the speed of image encryption is also faster than that of high-dimensional chaotic maps. At the same time, a novel lifting wavelet transform algorithm is adopted and optimized to reduce the correlation of the data and speed up image processing. The security of the new system is also guaranteed by hashing its key. The experimental results, security analysis and comparison with existing methods all confirm that the proposed algorithm has good performance, high security and complex chaotic behavior.