Spatial chaos-based image encryption design

In recent years, the chaos based cryptographic algorithms have suggested some new and efficient ways to develop secure image encryption techniques, but the drawbacks of small key space and weak security in one-dimensional chaotic cryptosystems are obvious. In this paper, permutation and substitution methods are incorporated to present a stronger image encryption algorithm. Spatial chaotic maps are used to realize the position permutation, and to confuse the relationship between the cipher-image and the plain-image. The experimental results demonstrate that the suggested encryption scheme of image has the advantages of large key space and high security; moreover, the distribution of grey values of the encrypted image has a random-like behavior. Supported by the National Natural Science Foundation of China (Grant No. 60874009) and the Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 200444)     

A fast chaos-based symmetric image cryptosystem with an improved diffusion scheme

In recent years, a number of chaos-based image cryptosystems have been proposed to meet the increasing demand for real-time secure image transmission. In this paper, an improved diffusion scheme named continuous diffusion strategy is proposed to promote the efficiency of the conventional permutation–diffusion type image cipher. The new scheme contains a supplementary diffusion procedure after the conventional diffusion process and the control parameters are altered by the cipher image after the first diffusion procedure. As a result, the difference can be introduced at the beginning and spread out to the whole image, and hence the same level of security can be achieved with fewer overall rounds. Moreover, to further enhance the confusion effect of the diffusion operation, an intensive diffusion approach is proposed, using stretched key stream elements to perform a cyclic shift to the cipher pixels. Extensive cryptanalysis has been performed using differential analysis, key space analysis, key sensitivity analysis and various statistical analyses. Experiment results demonstrate that the new scheme has a high level of security and fast encryption speed for practical image encryption.     

A general multi-secret visual cryptography scheme

In a (k, n) visual cryptography scheme (VCS), a secret image is encoded into n shadow images that are distributed to n participants. Any k participants can reveal the secret image by stacking their shadow images, and less than k participants have no information about the secret image. In this paper we consider the case when the secret image is more than one, and this is a so-called multi-secret VCS (MVCS). The previous works on MVCS are all the simple 2-out-of-2 cases. In this paper, we discuss a general (k, n)-MVCS for any k and n. This paper has three main contributions: (1) our scheme is the first general (k, n)-MVCS, which can be applied on any k and n, (2) we give the formal security and contrast conditions of (k, n)-MVCS and (3) we theoretically prove that the proposed (k, n)-MVCS satisfies the security and contrast conditions.     

An image encryption scheme using lightweight bit-level confusion and cascade cross circular diffusion

Recently, quite a lot of chaos-based image encryption schemes have been proposed. Most of them adopt the traditional permutation and diffusion operations. The drawbacks are: (1) the architecture is not sensitive to changes in the plain-image; (2) they are insecure upon chosen/known plain-image attack. Due to the favorable properties of bit-level permutation, we propose a lightweight bit-level confusion and cascade cross circular diffusion to enhance the security of the cryptosystem and to reduce the computation redundancy in traditional architectures. Simulations have been carried out and the results demonstrate the superior security and high efficiency of the proposed scheme.     

基于gyrator变换和矢量分解的非对称图像加密方法

本文结合矢量分解和gyrator变换的数学实现得到了一种新的非对称图像加密算法,它将待加密图像先通过矢量分解加密到两块纯相位板中,然后利用从gyrator变换的数学实现中推导出来的加密算法加密其中一块相位板,获得最终的实值密文.另一块相位板作为解密密钥.算法的解密密钥不同于加密密钥,实现了非对称加密,加密过程中产生的两个私钥增大了算法的安全性.数值模拟结果验证了该算法的可行性和有效性.     

Color image encryption using spatial bit-level permutation and high-dimension chaotic system

This paper proposes a bit-level permutation and high-dimension chaotic map to encrypt color image. Firstly, convert the plain color image of size (M × N) into a grayscale image of size (M × 3N), then transform it into a binary matrix, and permute the matrix at bit-level by the scrambling mapping generated by piecewise linear chaotic map (PWLCM). Secondly, use Chen system to confuse and diffuse the red, green and blue components simultaneously. Experiment results and security analysis not only show that the scheme can achieve good encryption result, but also that the key space is large enough to resist against common attack.     

An image encryption scheme using generalized Arnold map and affine cipher

This paper aims to provide an image encryption scheme with an efficient bit-level permutation and a pixel-level diffusion procedure. In the bit-level permutation, we divide each pixel into 8 bits, and arrange the positions of each bit by the generalized Arnold map in row and column direction. Hence, a significant diffusion effect is happened in the bit-level permutation. In the pixel-level diffusion procedure, we apply affine cipher to change the gray value and the histogram distribution of the permutated image. Various types of security analyses demonstrate that the proposed scheme is competitive with that ordinary permutation–diffusion type image cipher and proper for practical image encryption.     

Image sharing scheme based on discrete fractional random transform

We present a novel image sharing algorithm based on the discrete fractional random transform (DFRNT). The secret image is shared into several shadow images in the DFRNT domain together with some noise images as the encryption keys to increase the security. The decryption only requires a part of shadow images and therefore is independent of those noise images. The (t,n) threshold sharing scheme can be implemented completely by the proposed algorithm. The numerical simulations have demonstrated the effectiveness of this image sharing scheme.     

Quantum-Secret-Sharing Scheme Based on Local Distinguishability of Orthogonal Seven-Qudit Entangled States

The concept of judgment space was proposed by Wang et al. (Phys. Rev. A 95, 022320, 2017), which was used to study some important properties of quantum entangled states based on local distinguishability. In this study, we construct 15 kinds of seven-qudit quantum entangled states in the sense of permutation, calculate their judgment space and propose a distinguishability rule to make the judgment space more clearly. Based on this rule, we study the local distinguishability of the 15 kinds of seven-qudit quantum entangled states and then propose a (k, n) threshold quantum secret sharing scheme. Finally, we analyze the security of the scheme.     

A novel chaos-based bit-level permutation scheme for digital image encryption

Confidentiality is an important issue when digital images are transmitted over public networks, and encryption is the most useful technique employed for this purpose. Image encryption is somehow different from text encryption due to some inherent features of image such as bulk data capacity and high correlation among pixels, which are generally difficult to handle by conventional algorithms. Recently, chaos-based encryption has suggested a new and efficient way to deal with the intractable problems of fast and highly secure image encryption. This paper proposes a novel chaos-based bit-level permutation scheme for secure and efficient image cipher. To overcome the drawbacks of conventional permutation-only type image cipher, the proposed scheme introduced a significant diffusion effect in permutation procedure through a two-stage bit-level shuffling algorithm. The two-stage permutation operations are realized by chaotic sequence sorting algorithm and Arnold Cat map, respectively. Results of various types of analysis are interesting and indicate that the security level of the new scheme is competitive with that of permutation-diffusion type image cipher, while the computational complexity is much lower. Therefore the new scheme is a good candidate for real-time secure image communication applications.     

Steganography and authentication in image sharing without parity bits

Recently, a polynomial-based (k, n) steganography and authenticated image sharing (SAIS) scheme was proposed to share a secret image into n stego-images. At the same time, one can reconstruct a secret image with any k or more than k stego-images, but one cannot obtain any information about the secret from fewer than k stego-images. The beauty of a (k, n)-SAIS scheme is that it provides the threshold property (i.e., k is the threshold value), the steganography (i.e., stego-images look like cover images), and authentication (i.e., detection of manipulated stego-images). All existing SAIS schemes require parity bits for authentication. In this paper, we present a novel approach without needing parity bits. In addition, our (k, n)-SAIS scheme provides better visual quality and has higher detection ratio with respect to all previous (k, n)-SAIS schemes.     

An improved hierarchical fragile watermarking scheme using chaotic sequence sorting and subblock post-processing

The original hierarchical watermarking scheme for image tamper detection and recovery has simple computation and high performance precision which can achieve 2 × 2 subblock. However, four-scanning and blind attacks have been proposed recently on this scheme. We generalize these attacks and analyze the cause of security flaws. We think that it is promising to improve the original scheme's security and keep its merit at the same time. In order to defeat these attacks, we develop an improved method to generate a block mapping sequence by sorting the chaotic sequence and add the chaotic encryption and permutation based on the exact content of each subblock to be the post-processing of the 3-tuple watermark. Our method uses the simple watermarking scheme and satisfies the performance requirements of fragile watermarking, such as high-precision tamper detection, localization and recovery. Theoretical analysis and computer simulation demonstrate that our proposed scheme is much more secure and can overcome possible attacks.     

Breaking a novel image fusion encryption algorithm based on DNA sequence operation and hyper-chaotic system

Recently, a novel image fusion encryption algorithm based on DNA sequence operation and hyper-chaotic system was proposed. It was reported that the scheme can be broken with 4mn/3 +1 chosen plain-images and the corresponding cipher-images, where mn is the size of the plain-image. This paper re-evaluates the security of the encryption scheme and finds that the encryption scheme can be broken with less than ⌈ log ₂(4mn)/2 ⌉ +1 chosen plain-images, even three in many cases. The effectiveness of the proposed chosen-plaintext attack is supported by theoretical analysis, and verified by experimental results.     

A new image encryption algorithm based on hyper-chaos

This Letter presents a new image encryption scheme, which employs an image total shuffling matrix to shuffle the positions of image pixels and then uses a hyper-chaotic system to confuse the relationship between the plain-image and the cipher-image. The experimental results demonstrate that the suggested encryption algorithm of image has the advantages of large key space and high security, and moreover, the distribution of grey values of the encrypted y image has a random-like behavior.     

Synchronization of spatiotemporal semiconductor lasers and its application in color image encryption

Optical chaos is a topic of current research characterized by high-dimensional nonlinearity which is attributed to the delay-induced dynamics, high bandwidth and easy modular implementation of optical feedback. In light of these facts, which add enough confusion and diffusion properties for secure communications, we explore the synchronization phenomena in spatiotemporal semiconductor laser systems. The novel system is used in a two-phase colored image encryption process. The high-dimensional chaotic attractor generated by the system produces a completely randomized chaotic time series, which is ideal in the secure encoding of messages. The scheme thus illustrated is a two-phase encryption method, which provides sufficiently high confusion and diffusion properties of chaotic cryptosystem employed with unique data sets of processed chaotic sequences. In this novel method of cryptography, the chaotic phase masks are represented as images using the chaotic sequences as the elements of the image. The scheme drastically permutes the positions of the picture elements. The next additional layer of security further alters the statistical information of the original image to a great extent along the three-color planes. The intermediate results during encryption demonstrate the infeasibility for an unauthorized user to decipher the cipher image. Exhaustive statistical tests conducted validate that the scheme is robust against noise and resistant to common attacks due to the double shield of encryption and the infinite dimensionality of the relevant system of partial differential equations.     

A Secret Sharing Scheme for Quantum Gray and Color Images Based on Encryption

This paper is concerned with the better security of quantum image secret sharing (QISS) algorithm. The improved QISS (IQISS) scheme is implemented on both quantum gray image (FRQI) and quantum color image (MCQI). The new IQISS scheme comprises efficient sharing process and recovering process. The core idea of the sharing process is to combine encryption and measurement for two types of quantum secret images to acquire the quantum shadow images. In the recovering process, strip operation is firstly utilized on the shadow images. Afterwards, the decryption algorithm is used to recover the original quantum secret image. Experiments demonstrate that significant improvements in the security are in favor of the proposed approach.

     

Constructions and properties of k out of n scalable secret image sharing

Recently, Wang et al. introduced a novel (2, n) scalable secret image sharing (SSIS) scheme, which can gradually reconstruct a secret image in a scalable manner in which the amount of secret information is proportional to the number of participants. However, Wang et al.’s scheme is only a simple 2-out-of-n case. In this paper, we consider (k, n)-SSIS schemes where a qualified set of participants consists of any k participants. We provide two approaches for a general construction for any k, 2 ? k ? n. For the special case k = 2, Approach 1 has the lesser shadow size than Wang et al.’s (2, n)-SSIS scheme, and Approach 2 is reduced to Wang et al.’s (2, n)-SSIS scheme. Although the authors claim that Wang et al.’s (2, n)-SSIS scheme can be easily extended to a general (k, n)-SISS scheme, actually the extension is not that easy as they claimed. For the completeness of describing the constructions and properties of a general (k, n)-SSIS scheme, both approaches are introduced in this paper.     

Improved Group Signature Scheme Based on Quantum Teleportation

Recently, Wen et al. proposed a group signature scheme based on quantum teleportation (Wen et al. 81(5):055001, 2010). In this paper, we find that it is vulnerable to the inside attack, by which all other legal members of the group can forge the signature utilizing the anti-commutative relationship between the Pauli operation Y and the encryption operation H, and the public board. Then we present an improved scheme where the eavesdropping process after the transmission is involved to increase the security.     

A novel color image encryption scheme using fractional-order hyperchaotic system and DNA sequence operations

In this paper, Adomian decomposition method(ADM) with high accuracy and fast convergence is introduced to solve the fractional-order piecewise-linear(PWL) hyperchaotic system. Based on the obtained hyperchaotic sequences,a novel color image encryption algorithm is proposed by employing a hybrid model of bidirectional circular permutation and DNA masking. In this scheme, the pixel positions of image are scrambled by circular permutation, and the pixel values are substituted by DNA sequence operations. In the DNA sequence operations, addition and substraction operations are performed according to traditional addition and subtraction in the binary, and two rounds of addition rules are used to encrypt the pixel values. The simulation results and security analysis show that the hyperchaotic map is suitable for image encryption, and the proposed encryption algorithm has good encryption effect and strong key sensitivity. It can resist brute-force attack, statistical attack, differential attack, known-plaintext, and chosen-plaintext attacks.     

Hyperchaotic Image Encryption Based on Multiple Bit Permutation and Diffusion

Image security is a hot topic in the era of Internet and big data. Hyperchaotic image encryption, which can effectively prevent unauthorized users from accessing image content, has become more and more popular in the community of image security. In general, such approaches conduct encryption on pixel-level, bit-level, DNA-level data or their combinations, lacking diversity of processed data levels and limiting security. This paper proposes a novel hyperchaotic image encryption scheme via multiple bit permutation and diffusion, namely MBPD, to cope with this issue. Specifically, a four-dimensional hyperchaotic system with three positive Lyapunov exponents is firstly proposed. Second, a hyperchaotic sequence is generated from the proposed hyperchaotic system for consequent encryption operations. Third, multiple bit permutation and diffusion (permutation and/or diffusion can be conducted with 1–8 or more bits) determined by the hyperchaotic sequence is designed. Finally, the proposed MBPD is applied to image encryption. We conduct extensive experiments on a couple of public test images to validate the proposed MBPD. The results verify that the MBPD can effectively resist different types of attacks and has better performance than the compared popular encryption methods.