Block based embedding of encrypted watermarks using singular value decomposition

Watermarking is a solution to the problem of copyright protection of multimedia documents over the Internet. This paper presents a block based watermarking scheme using the singular value decomposition (SVD) algorithm to embed encrypted watermarks into digital images. The paper compares between the traditional method of Liu and the proposed method for embedding encrypted watermarks. Also, a permutation based encryption algorithm and a diffusion based encryption algorithm are compared as the watermark encryption algorithms. Experimental results show that the proposed method is superior to the traditional method of Liu for embedding encrypted watermarks and extracting them efficiently under attacks. Results also show that it is preferred to use permutation based encryption algorithms than diffusion based encryption algorithms for watermark encryption due to their lower sensitivity to attacks.     

A Chaotic-Based Encryption/Decryption Framework for Secure Multimedia Communications

Chaos-based encryption has shown an increasingly important and dominant role in modern multimedia cryptography compared with traditional algorithms. This work proposes novel chaotic-based multimedia encryption schemes utilizing 2D alteration models for high secure data transmission. A novel perturbation-based data encryption for both confusion and diffusion rounds is proposed. Our chaotification structure is hybrid, in which multiple maps are combined combines for media encryption. Blended chaotic maps are used to generate the control parameters for the permutation (shuffling) and diffusion (substitution) structures. The proposed schemes not only maintain great encryption quality reproduced by chaotic, but also possess other advantages, including key sensitivity and low residual clarity. Extensive security and differential analyses documented that the proposed schemes are efficient for secure multimedia transmission as well as the encrypted media possesses resistance to attacks. Additionally, statistical evaluations using well-known metrics for specific media types, show that proposed encryption schemes can acquire low residual intelligibility with excessive nice recovered statistics. Finally, the advantages of the proposed schemes have been highlighted by comparing it against different state-of-the-art algorithms from literature. The comparative performance results documented that our schemes are extra efficacious than their data-specific counterpart methods.     

Towards Secure Big Data Analysis via Fully Homomorphic Encryption Algorithms

Privacy-preserving techniques allow private information to be used without compromising privacy. Most encryption algorithms, such as the Advanced Encryption Standard (AES) algorithm, cannot perform computational operations on encrypted data without first applying the decryption process. Homomorphic encryption algorithms provide innovative solutions to support computations on encrypted data while preserving the content of private information. However, these algorithms have some limitations, such as computational cost as well as the need for modifications for each case study. In this paper, we present a comprehensive overview of various homomorphic encryption tools for Big Data analysis and their applications. We also discuss a security framework for Big Data analysis while preserving privacy using homomorphic encryption algorithms. We highlight the fundamental features and tradeoffs that should be considered when choosing the right approach for Big Data applications in practice. We then present a comparison of popular current homomorphic encryption tools with respect to these identified characteristics. We examine the implementation results of various homomorphic encryption toolkits and compare their performances. Finally, we highlight some important issues and research opportunities. We aim to anticipate how homomorphic encryption technology will be useful for secure Big Data processing, especially to improve the utility and performance of privacy-preserving machine learning.     

混沌参数调制下RSA数据加密算法研究

随着网络信息通讯技术的发展,信息数据的通讯安全成为信息化网络信息数据通讯过程中的重要问题。面对大量侵入程序与数据漏洞的威胁,一套强有效的数据加密算法成为数据研究领域的研究方向。RSA数据加密算法作为如今常用的安全性最高的算法,在大数据动态数据节点混沌排列的条件下,无法有效保证数据的加密安全。混沌参数下,出现加密逻辑断裂、溢出、数列逆排等严重的算法漏洞。对此,提出混沌参数调制下RSA数据加密算法研究,采用混沌参数特征处理单元、特征序列逻辑控制单元与混沌FIE-RSA算法,对传统RSA加密算法存在的问题进行针对性解决。通过仿真实验证明,提出的混沌参数调制下RSA数据加密算法研究中,采用的一系列方法具有加密处理响应速度快、处理运算时间短、加密安全度高、反破解性能强等特点。     

A Bit Shift Image Encryption Algorithm Based on Double Chaotic Systems

A chaotic system refers to a deterministic system with seemingly random irregular motion, and its behavior is uncertain, unrepeatable, and unpredictable. In recent years, researchers have proposed various image encryption schemes based on a single low-dimensional or high-dimensional chaotic system, but many algorithms have problems such as low security. Therefore, designing a good chaotic system and encryption scheme is very important for encryption algorithms. This paper constructs a new double chaotic system based on tent mapping and logistic mapping. In order to verify the practicability and feasibility of the new chaotic system, a displacement image encryption algorithm based on the new chaotic system was subsequently proposed. This paper proposes a displacement image encryption algorithm based on the new chaotic system. The algorithm uses an improved new nonlinear feedback function to generate two random sequences, one of which is used to generate the index sequence, the other is used to generate the encryption matrix, and the index sequence is used to control the generation of the encryption matrix required for encryption. Then, the encryption matrix and the scrambling matrix are XORed to obtain the first encryption image. Finally, a bit-shift encryption method is adopted to prevent the harm caused by key leakage and to improve the security of the algorithm. Numerical experiments show that the key space of the algorithm is not only large, but also the key sensitivity is relatively high, and it has good resistance to various attacks. The analysis shows that this algorithm has certain competitive advantages compared with other encryption algorithms.     

Double Security Level in Optical Communication Systems Using Combined Modulation Formats

A new optical communication system exhibiting a double security level is presented. Information coding is based on combined modulation formats of two data streams over the same optical carrier. Incoherent and coherent optical encryption algorithms are presented and are theoretically analyzed. The optical encryption method is transparent to data bit rates. Furthermore, it requires "on-line" data decoding with no possibility of recording and further processing. The incoherent scheme is very practical and can be implemented in existing optical communications systems, using currently available technology. Computer experiments of the incoherent method indicate less than 25 dB of signal to noise ratio required for 10-9 bit error rate and ineligible information decoding time of more than 10 8 years.     

Image encryption using high-dimension chaotic system

In recent years, the chaos based cryptographic algorithms have suggested some new and efficient ways to develop secure image encryption techniques. This paper proposes a new approach for image encryption based on a high-dimensional chaotic map. The new scheme employs the Cat map to shuffle the positions, then to confuse the relationship between the cipher-image and the plain-image using the high-dimensional Lorenz chaotic map preprocessed. The results of experimental, statistical analysis and key space analysis show that the proposed image encryption scheme provides an efficient and secure way for real-time image encryption and transmission.     

Quantum Image Encryption Based on Quantum Image Decomposition

Aiming at the slow processing speed of classic image encryption algorithms and the security analysis of existing quantum image encryption algorithms, this paper combines the representation method of quantum images and proposes a quantum image encryption algorithm based on image correlation decomposition. Using the principle of quantum state superposition and measurement, the association between image pixels is established, the image is decomposed into a series of feature sub-images and stored in a complete binary tree set, and different sub-images are operated and encrypted by random phase operation and quantum rotation operation. Then superimpose all the sub-images to obtain the ciphertext image. The algorithm has a larger key space so that it can resist brute force attacks. At the same time, the quantum encryption algorithm has lower computational complexity than classic encryption algorithms. In addition, because the ciphertext image is transmitted in the communication channel in the form of a quantum state, the security of quantum image encryption also surpasses the security of classical image encryption.

     

Image encryption and decryption using fractional Fourier transform and radial Hilbert transform

A technique for image encryption using fractional Fourier transform (FRT) and radial Hilbert transform (RHT) is proposed. The spatial frequency spectrum of the image to be encrypted is first segregated into two parts/channels using RHT, and image subtraction technique. Each of these channels is encrypted independently using double random phase encoding in the FRT domain. The different fractional orders and random phase masks used during the process of encryption and decryption are the keys to enhance the security of the proposed system. The algorithms to implement the proposed encryption and decryption scheme are discussed, and results of digital simulation are presented.     

Color image encryption and decryption using fractional Fourier transform

We propose the encryption of color images using fractional Fourier transform (FRT). The image to be encrypted is first segregated into three color channels: red, green, and blue. Each of these channels is encrypted independently using double random phase encoding in the FRT domain. The different fractional orders and random phase masks used during the process of encryption and decryption are the keys to enhance the security of the proposed system. The algorithms to implement the proposed encryption and decryption scheme are discussed, and results of digital simulation are presented. The technique is shown to be a powerful one for colored text encryption. We also outline the implementation of the algorithm and examine its sensitiveness to changes in the fractional order during decryption.     

双随机相位加密系统的已知明文攻击

运用密码分析学的方法对双随机相位加密系统进行了初步的安全性分析.研究结果表明，该系统属于线性的对称分组密码系统，线性性质为其安全性留下隐患.在已知明文攻击下，攻击者可通过常规的相位恢复算法获得4-f系统输入平面的随机相位函数密钥，继而可轻易推出频谱平面的随机相位函数密钥，从而攻破此密码系统. 关键词： 光学信息安全 双随机相位加密 密码分析学 已知明文攻击     

Architecture of multicast centralized key management scheme using quantum key distribution and classical symmetric encryption

Multicasting refers to the transmission of a message or information from one sender to multiple receivers simultaneously. Although encryption algorithms can be used to secure transmitted messages among group members, still there are many security aspects for designing a secured multicast cryptosystem. The most important aspects of Multicasting are key generation and management. The researchers have proposed several approaches for solving problems of multicast key distribution and management. In this paper, a secure key generation and distribution solution has been proposed for a single host sending to two or more (N) receivers using centralized Quantum Multicast Key Distribution Centre “QM_KDC” and classical symmetric encryption. The proposed scheme uses symmetric classical algorithms for encryption and decryption transmitted messages among multicast group members, but the generated keys which are used for authentication, encryption and decryption also play an important role for designing a secured multicast cryptosystem come from QKD protocols. Authentication verified using EPR entangled Photons and controlled-NOT gate. Multiple requests for initialization as well for transmitting sensitive information handled through priority and sensitivity levels. Multiple members’ communication is achieved with full or partial support of QM_KDC.     

基于Q-plate的双图像非对称偏振加密

基于Q-plate提出了一种对两幅图像做非对称偏振加密的新方法.在该方法中,首先,将待加密的两幅图像通过干涉分解成两块纯相位板;其次,将这两块纯相位板分别编码到偏振光的两个正交分量中;最后,利用Q-plate和像素化的偏振片改变这束光的偏振分布,达到对图像的加密效果,用电荷耦合器件接收输出面的强度分布图作为最终的密文.其中一块纯相位板作为解密密钥.算法的解密密钥不同于加密密钥,由此实现了非对称加密.由于Q-plate是电调控的,它的每个像素点的光轴各不相同,所以能够根据描述变面结构空间旋转率的常数q来改变每个像素的偏振态.加密过程中用Q-plate的q值和像素化的偏振片的偏振角度作为加密密钥,这两个加密密钥具有很高的敏感性,极大地提高了算法的安全性.数值模拟结果验证了该方法的可行性和有效性.     

三维可逆混沌映射的图像加密算法

提出了一种三维可逆混沌映射图像加密算法。基于Line map二维混沌可逆映射,推导了该三维可逆映射的数学表达式。将灰度图像用一个三维矩阵数据描述,并按照所提出的算法将其组成一个二维的二进制图像。首先对此图像应用Line map二维混沌可逆映射进行像素置乱处理,然后再将置乱后的二进制图像还原成十进制的灰度图像,这样就得到了加密后的图像。所提出的方法可以通过一次三维可逆混沌映射同时实现图像加密的两个步骤,即像素置乱和像素混淆。仿真实验结果表明了该算法的有效性,且加密速度快、安全性高、简单易行。     

对一类超混沌图像加密算法的密码分析与改进

对一种超混沌图像加密算法及其改进版进行了安全性分析, 结果表明该类算法的置乱过程都是与混淆过程相脱离的, 且混淆过程的加密公式简单; 因此都不能抵抗选择明文和选择密文攻击. 进而提出了一种改进的加强型超混沌图像加密算法; 改进算法包含两轮像素值替代加密操作, 并使得密文与明文、密钥之间的关系更复杂. 安全性分析和实验测试表明, 改进算法不仅克服了原算法不能抵御选择明文和选择密文攻击的缺陷; 而且具有时间开销更小和抗差分攻击性能更好的优势.     

A New Algorithm for Digital Image Encryption Based on Chaos Theory

In recent decades, image encryption, as one of the significant information security fields, has attracted many researchers and scientists. However, several studies have been performed with different methods, and novel and useful algorithms have been suggested to improve secure image encryption schemes. Nowadays, chaotic methods have been found in diverse fields, such as the design of cryptosystems and image encryption. Chaotic methods-based digital image encryptions are a novel image encryption method. This technique uses random chaos sequences for encrypting images, and it is a highly-secured and fast method for image encryption. Limited accuracy is one of the disadvantages of this technique. This paper researches the chaos sequence and wavelet transform value to find gaps. Thus, a novel technique was proposed for digital image encryption and improved previous algorithms. The technique is run in MATLAB, and a comparison is made in terms of various performance metrics such as the Number of Pixels Change Rate (NPCR), Peak Signal to Noise Ratio (PSNR), Correlation coefficient, and Unified Average Changing Intensity (UACI). The simulation and theoretical analysis indicate the proposed scheme’s effectiveness and show that this technique is a suitable choice for actual image encryption.     

Fractional Fourier transform based image multiplexing and encryption technique for four-color images using input images as keys

A digital technique for multiplexing and encryption of four RGB images has been proposed using the fractional Fourier transform (FRT). The four input RGB images are first converted into their indexed image formats and subsequently multiplexed into a single image through elementary mathematical steps prior to the encryption. The encryption algorithm uses two random phase masks in the input- and the FRT domain, respectively. These random phase masks are especially designed using the input images. As the encryption is carried out through a single channel, the technique is more compact and faster as compared to the multichannel techniques. Different fractional orders, the random masks in input-, and FRT domain are the keys for decryption as well as de-multiplexing. The algorithms to implement the proposed multiplexing-, and encryption scheme are discussed, and results of digital simulation are presented. Simulation results show that the technique is free from cross-talk. The performance of the proposed technique has also been analyzed against occlusion, noise, and attacks using partial windows of the correct random phase keys. The robustness of the technique against known-, and chosen plain-text attacks has also been explained.     

Optical image conversion and encryption by diffraction,phase retrieval algorithm and incoherent superposition

In this paper, an optical encryption system is proposed based on tricolor principle, Fresnel diffraction, and phase iterative algorithms. Different from the traditional encryption system, the encrypted image of this system is a color image and the plaintext of it is a gray image, which can achieve the combination of a color image and a gray image and the conversion of one image to another image. Phase masks can be generated by using the phase iterative algorithms in this paper. The six phase masks and the six diffracting distances are all essential keys in the process of decryption, which can greatly enhance the system security. Numerical simulations are shown to prove the possibility and safety of the method.     

Modified Gerchberg–Saxton (G-S) Algorithm and Its Application

The Gerchberg–Saxton (G-S) algorithm is a phase retrieval algorithm that is widely used in beam shaping and optical information processing. However, the G-S algorithm has difficulty obtaining the exact solution after iterating, and an approximate solution is often obtained. In this paper, we propose a series of modified G-S algorithms based on the Fresnel transform domain, including the single-phase retrieval (SPR) algorithm, the double-phase retrieval (DPR) algorithm, and the multiple-phase retrieval (MPR) algorithm. The analysis results show that the convergence of the SPR algorithm is better than that of the G-S algorithm, but the exact solution is not obtained. The DPR and MPR algorithms have good convergence and can obtain exact solutions; that is, the information is recovered losslessly. We discuss the security advantages and verification reliability of the proposed algorithms in image encryption. A multiple-image encryption scheme is proposed, in which n plaintexts can be recovered from n ciphertexts, which greatly improves the efficiency of the system. Finally, the proposed algorithms are compared with the current phase retrieval algorithms, and future applications are discussed. We hope that our research can provide new ideas for the application of the G-S algorithm.     

Image encryption based on the multiple-parameter discrete fractional Fourier transform and chaos function

In recent years, the chaos-based cryptographic algorithms have suggested some new and efficient ways to develop secure image encryption techniques. In this paper, we propose a new approach for image encryption based on the multiple-parameter discrete fractional Fourier transform and chaotic logistic maps in order to meet the requirements of the secure image transmission. In the proposed image encryption scheme, the image is encrypted by juxtaposition of sections of the image in the multiple-parameter discrete fractional Fourier domains and the alignment of sections is determined by chaotic logistic maps. This method does not require the use of phase keys. The new method has been compared with several existing methods and shows comparable or superior robustness to blind decryption.