Nowadays, there is an explosive growth in the digital multimedia creation, capturing, processing and distribution. Protecting the multimedia contents from copyright infringement has become a major concern. Encryption and watermarking are two complementary techniques that are used for protecting the multimedia data. In this paper, a proposed hybrid encryption-watermarking algorithm for copyright protection is proposed. The watermarking phase of this proposed algorithm is based on combining the discrete wavelet transform (DWT), the discrete cosine transform (DCT), and the singular value decomposition (SVD), while the encryption phase is based on using four chaotic maps with different dimensions. The proposed watermarking scheme uses a new PN-codes embedding strategy of the watermark into the cover image. This strategy allows decreasing the embedding strength factor of the scheme to a value that maximizes imperceptibility performance while maintaining acceptable robustness of the watermarking scheme. The performance of the proposed watermarking scheme is evaluated individually based on the robustness and the imperceptibility measures. This scheme is compared with some recent existing algorithms and experimental results show the improvements of the proposed algorithm over these algorithms. On the other hand, the proposed chaos-based encryption algorithm used four chaotic maps of different dimensions and it has two diffusion stages rather than one to improve the algorithm efficiency. The proposed encryption algorithm is tested using different experiments. The experimental results demonstrate that the proposed encryption algorithm shows advantages of large key space, high resistance against differential attacks and high security analysis such as statistical analysis, and sensitivity analysis. Compared to some traditional and recent encryption algorithms, the proposed encryption algorithm is much more secure. Finally experimental tests demonstrate that the proposed hybrid encryption-watermarking algorithm introduces high degree of efficiency, robustness, and security. General TermsHybrid Image watermarking schemes, Chaotic maps based cryptography, Statistical attacks, and Differential attacks.

Intensive studies have been done to get robust encryption algorithms. Due to the importance of image information, optical encryption has played a vital role in information security. Many optical encryption schemes have been proposed but most of them suffer from poor robustness. In this paper six proposed algorithms will be presented for optical encryption to be robust to severe attacks: composite attack. Three of these approaches are based on one level Discrete Wavelet Transform (DWT) and the others are based on Wavelet Packet (WP). Not only will new techniques be presented but also a new proposed chaotic map has been developed as random keys for all algorithms. After extensive comparative study with some traditional techniques, it has been found that the novel algorithms have achieved better performance versus conventional ones. Also it has been found that WP based algorithms have achieved better performance than DWT based ones against severe composite attacks.

This paper presents two fragile watermarking schemes for digital image authentication with tamper detection and localization. We combine a proposed chaos-based encryption algorithm with the two schemes in order to improve the security, tamper detection sensitivity and tamper localization accuracy of the two schemes. The first proposed fragile watermarking scheme can be classified as a block-based scheme that divides the cover image into non-overlapping 4×4 blocks. We generate an 8-bit authentication watermark for each cover image block based on the block contents and then we use the proposed chaos-based encryption algorithm to encrypt this watermark. These encrypted 8-bit watermark are then embedded into the least significant bits (LSBs) of the highest intensity eight pixels of the block. On the other hand, the second proposed watermarking scheme can be classified as a wavelet-based scheme which uses an external secret watermark. This watermark is encrypted using the proposed chaos-based encryption algorithm. We decompose the cover image using Discrete Wavelet Transform (DWT) and then we use the encrypted watermark to update the approximation coefficients (LL sub-band) of the image. Various experimental tests are carried out to evaluate the performance of the two schemes. Experimental results demonstrate that the two proposed schemes can detect and localize tampering attacks accurately. The two schemes also achieve high degree of imperceptibility performance. Compared to some fragile watermarking schemes, our proposed schemes are more secure and efficient.

In this paper, we propose a double color images encryption scheme based on Deoxyribonucleic Acid (DNA) sequence, chaotic system and block permutation. Mean Square Error (MSE) of the double images, LSS and 2D-LASM chaotic systems are firstly employed to generate the key streams. Then, divide the plain-images into equal blocks and scramble the blocks using the key streams. Next, encode the permuted images into the DNA matrices according to the DNA encoding rules and a DNA XOR operation is carried out on the DNA matrices. Finally, decode the encrypted the DNA matrices via the DNA decoding rules, and a pixel-level diffusion is further adopted to strengthen the security and sensitivity of the cryptosystem, and the resulting cipher-images are obtained. The experimental results show that the presented encryption algorithm has the advantages of large key space and high security, and fast encryption/decryption speed. 1. Introduction With the rapid development of information and network technologies, a great many of digital multimedia data are transmitted over the public networks. It is necessary to protect the image information against the unauthorized access, usage, disruption and destruction. In the past years, many encryption methods have been proposed, such as DES, IDEA and RSA etc. However, these traditional encryption schemes are unsuitable for the digital images, because some inherent features of the images such as bulk data capacity, and strong correlation among pixels and high computation complexity [1,2]. Considering the desirable properties of extreme sensitivity to initial conditions and parameters, the close relationship between chaos and cryptography has been revealed [3]. The simple low-dimensional (LD) chaotic systems can be realized conveniently in engineering due to their simple structure, but they also have some drawbacks such as limited/discontinuous chaotic range, the non-uniform data distribution, and the vulnerability to low-computation-cost analysis using iteration and correlation functions [4]. In contrast to the LD chaotic systems, the high-dimensional (HD) chaotic systems have complex structures and chaotic behaviors. Unfortunately, the complex structure and multiple parameters of the HD chaotic systems increase the cost of hardware/software implementations and the computation complexity [5]. Hence, considering the trade-offs between the security and speed, it is essential to design the image encryption algorithms based on the LD chaotic systems/maps with excellent performance. Since the pioneering work of Adleman [6], DNA computing has gained growing attention from many researchers in various fields such as biology, chemistry, mathematics, computer science etc. Recently, DNA-based image encryption has aroused great interest [7-15]. For example, Liu et al. [7] proposed a color image encryption algorithm based on DNA encoding and the Logistic map. But this cryptosystem is very weak to a chosen-plaintext attack [8]. An image fusion encryption scheme based on DNA sequence operation and Chen hyper-...

Nowadays, various types of attacks are imposed to multimedia during transmission. Also in many applications the security of information is very important. So the information encryption has become an important issue. Many encryption techniques have been proposed to achieve high robustness against different types of attacks and to save information from hackers. In this paper, a new chaotic based optical encryption that depends on Discrete Wavelet Transform (DWT) for image transformation will be introduced for color image encryption. Nine chaotic maps have been used in the proposed technique; eight of them were traditional and one is a new proposed map. As a result of extensive simulation results depending on various performance metrics it has been found that the proposed technique has given better robustness comparing to traditional algorithm.