![]() To meet these challenges, we propose a novel image encryption algorithm. For the latter, usually the key length is invariant, which is not flexible and may have some restrictions in the encryption. This will result in reducing efficiency of the algorithm. For the former, fractal coding operation itself may bring the time consumption. Many conventional fractal-based encryption methods are combined with fractal coding compression or treat the fractal image as a host image to hide some information, e.g., keys. made the optimal quantitative cryptanalysis of permutation-only multimedia ciphers against plaintext attacks. For some shortcomings in encryption algorithms, Li et al. ![]() Yuen made a cryptanalysis on secure fractal image coding based on fractal parameter encryption. ![]() Īt the same time, a great deal of analysis has been performed on the image encryption algorithms based on fractal sets or chaos sets. Tong proposed an image encryption scheme based on 3D baker with dynamical compound chaotic sequence cipher generator. Lin encrypted an image by assembling the fractal image additional method and the binary encoding method. Sun used a Mandelbrot set and the Hilbert transformation to generate the random key. Lock compressed the original picture for matrix multiplication with the fractal image. Rozouvan encrypted an image with the transformed Mandelbrot set. Liu studied a novel fractal cryptographic algorithm based on a fractal model and fractal dimension. Kumar proposed a method of encrypting a Mandelbrot set with the RSA method and Elliptical curve. Using the fractal set directly as the key is the common method. In the fractal research field, image encryptions are also explored. For example, Chen produced a key through 3D chaotic cat maps and operated a pixel value with XOR to get the cipher image. Among the algorithms utilizing the keys, there has been a great deal of research in chaotic cryptography. Combining the encryption with other data processing technologies, Hermassi introduced a new scheme based on joint compression and encryption using the Huffman code. Some algorithms are proposed according to the characteristics of the image itself, such as Yuen’s proposal of a chaos-based joint image compression and encryption algorithm using discrete cosine transformation (DCT) and Secure Hash Algorithm-1 (SHA-1). For instance, Shyu used random grids to accomplish the encryption of secret gray-scale and color images. Some algorithms are based on certain transformation rules. So, among the popular applications of multimedia, research on image encryption has both theoretical and practical significance.Ĭurrently, there are various kinds of image encryption techniques, including image-scrambling-based techniques, data-processing-based techniques, key-based encryption techniques, etc. Because the digital images have special coding structures and large amounts of data, the conventional encryption algorithm may change the original data format in the image encryption. Therefore, they have highly computational complexity. Most conventional encryption algorithms put the emphasis on text data or binary data. ![]() Nowadays, image encryption has been a focus in the research of information security. Especially because digital images contain so much information, security for images is a widespread concern. Due to a large number of threats against communications security, information protection has become an important issue. With the increasingly wide reach of the Internet, communications via Internet are getting more frequent.
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