Image Encryption Algorithms Based On Random Projection Partition And Chinese Remainder Theorem

With the rapid development of Internet and digital signal processing technology, digital media is widely applied to many fields and its security becomes an important issue. Digital image is one of the most popular digital media, and can vividly describe the real world. At present, digital image content security is a hot topic attracting attention of many researchers. Image encryption is an efficient technology of digital content protection. It converts input image into a cipher image with meaningless content, and can effectively solve the problem of image security. As the progress of computer software and hardware, computational performance is rapidly improved, and thus those image encryption algorithms requiring huge computations for brute-force attack are not secure and reliable. Meanwhile, with the popularity of smart mobile phone, camera and other acquiring equipments, more and more high-resolution images are generated. These demands require efficient image encryption algorithms. Aiming at these issues, this paper exploits random projection partition and Chinese remainder theorem to design secure and fast image encryption algorithms.This paper firstly introduces the background, basic principle and performance metrics of image encryption. Secondly, development and future direction of image encryption is reviewed. Finally, random projection partition and Chinese remainder theorem are separately exploited to design efficient image encryption algorithms, which are validated with many experiments. The main results of this paper are as follows:1. I proposed an image encryption algorithm based on random projection partition and chaotic systemThis algorithm randomly divides input image into overlapping blocks, and then further divides each block into 180 projection lines. Next, it use the skew tent chaotic system to generate a pool of secret data for encryption. For each projection line of every block, it is swapped with a corresponding projection line of another block, which is randomly selected and has no overlapping region with the block. Before swapping, a secret sequence is randomly selected from the pool of secret data, and used to encrypt the projection lines by the XOR operation. In other words, the swapping lines are the encrypted results. Finally, encrypted image is obtained by processing all projection lines of all image blocks with the above similar strategy. Theoretical analysis and experimental results show that the proposed algorithm is fast, secure and robust. It is superior to three image encryption algorithms.2. I proposed multi-image encryption with Chinese remainder theorem and spatiotemporal chaotic systemAiming at the problem of multi-image encryption, I proposed an encryption algorithm with Chinese remainder theorem and spatiotemporal chaotic system. This algorithm firstly concatenates the multiple input images to form an image, and uses spatiotemporal chaotic system to generate two secret sequences. Then, the proposed algorithm uses one secret sequence to scramble pixel positions, exploits Chinese remainder theorem to perform compression, and converts the compressed data into the data compatible with image format by number system conversion. Finally, another secret sequence is exploited to encrypt the converted data and the encrypted image is thus obtained. This algorithm can encrypt multiple input images with good efficiency. Experimental results show that the proposed algorithm is robust and secure, and is better than two existing algorithms.