Fast Image Encryption Based on Two-Stage Chunking Under XOR-Scrambling Framework

High resolution images containing personal information are often stored in semi trusted cloud platforms such as Baidu Cloud Drive. Encrypting them first and then uploading to the cloud can prevent privacy leaks. However, if such images need to be encrypted frequently or in bulk, the issue of time consumption will become apparent. To achieve fast encryption of high-definition images, a fast image encryption algorithm based on two-stage chunking using XOR-scrambling frame is proposed. Firstly, the image is divided into big blocks, and the pixel-level XOR-scrambling encryption is performed on them; on this basis, the image is further divided into small blocks and the positions of the small blocks are randomly shuffled. Since the encryption of each large block of the image follows the same principle as traditional XOR-scrambling encryption algorithm, the security of encryption is ensured. At the same time, Dividing the image into large blocks for encryption can greatly save overall encryption time. Randomly shuffling small blocks of the image can further increase the degree of pixels scrambling and improve the ability to resist the cropping attack of the encrypted image. The experimental results show that compared with the traditional algorithm, the proposed fast image encryption algorithms significantly reduce the encryption time, and the higher the image resolution, the more significant the reduction in the encryption time.