A cheating prevention scheme for binary visual cryptography with homogeneous secret images

In 1995, Naor and Shamir proposed the k-out-of-n visual cryptography scheme such that only more than or equal to k participants can visually recover the secret through superimposing their transparencies. Visual cryptography schemes have been extensively investigated since their invention and extended to numerous applications such as visual authentication and identification, steganography, and image encryption. In 2006, Horng et al. proposed that cheating is possible where some participants can deceive the remaining participants by delivering forged transparencies. Meanwhile, Horng et al. also proposed two cheating prevention schemes. One scheme, however, requires extra verification transparencies and the other needs larger transparencies. In other words, compared to visual cryptography, both schemes burden each participant with an additional problem of transparency management. In this paper, a more secure scheme is given to solve the cheating problem without extra burdens by adopting multiple distinct secret images. Moreover, for sharing these secret images simultaneously, the share construction method of visual cryptography is redesigned and extended by generic algorithms. Finally, the results of the experiment and security analysis show that not only the proposed scheme is more secure in comparison with the two previous cheating prevention schemes in the literature, but extra burdens are also eliminated.     

基于XOR的(2，2，n)多秘密视觉密码

针对现有多秘密视觉密码方案像素扩展度较大和相对差较小的问题,从像素扩展度与秘密数量之间的关系入手,通过设计关联算法和分享算法,提出了一种基于XOR运算的(2,2,n)多秘密视觉密码方案,该方案能够利用XOR和OR两种运算来恢复任意数量的秘密图像。实验结果表明,该方案在像素扩展度和相对差上与以往方案相比都有较大改善。     

Testing the randomness of shares in color visual cryptography

Pattern Analysis and Applications - The concept of black-and-white visual cryptography with two truly random shares, previously applied to color images, was improved by mixing the contents of the...     

Circular meaningful shares based (k,n) two in one image secret sharing scheme for multiple secret images

Multimedia Tools and Applications - Two in One Image Secret Sharing Scheme (TiOISSS) is a cryptographic technique which encrypts a secret image into n shares and the shares are decoded in two...     

A copyright protection scheme for digital images using visual cryptography technique

A robust copyright protection scheme for digital image is proposed in the paper. In the proposed scheme, the watermark does not require to be embedded into the protected image but is used to generate a secret image and a public image by using the visual cryptography technique. Then the secret image is registered to certified authority (CA) for further protection. In the step of watermark extraction, the watermark can be acquired by performing exclusive-OR (XOR) operation between the secret image and the public image. The experimental results show that the proposed scheme not only can clearly verify the copyright of the digital image, but also is robust to withstand several image processing attacks such as JPEG lossy compression, cropping, noise adding, sharpening and blurring attacks.     

A new definition of the contrast of visual cryptography scheme

In this paper, some of the known definitions of the contrast of the Visual Cryptography Scheme (VCS) are shown to be inappropriate, and a new definition of the contrast based on our observations is proposed. It is also shown how our new definition of the contrast agreed with our observations.     

A new visual evaluation criterion of visual cryptography scheme for character secret image

Multimedia Tools and Applications - Since visual cryptography scheme (VCS) was introduced by Naor and Shamir, contrast has been always regarded as an evaluation standard of visual quality of the...     

An efficient verifiable (t,n)-threshold secret image sharing scheme with ultralight shares

Multimedia Tools and Applications - A secret sharing scheme partitions a secret into a set of shares and distributes them among the eligible participants, with each participant receiving one share...     

一种高效的(t,n)门限可视密码方案

首先提出了一种多秘密共享方案,该方案共享t个多重秘密,需要计算t个联立方程。然后基于多秘密共享的思想,提出了一种新的(t,n)门限可视密码方案。该方案把一幅秘密图像分割成t幅子秘密图像,每幅子秘密图像是原始图像的1/t;然后再由t幅子秘密图像计算出n幅共享图像,秘密送给n个参与者,其中每个共享图像与子秘密图像同样大小。使得任意t个或更多的参与者合作能够恢复原始秘密图像,而任意少于t个参与者却得不到有关原始图像的任何信息。另外,恢复的图像和秘密图像完全一样,没有任何失真。新方案安全、有效,是一种完备的(t,n)门限方案,适用于把黑白、灰度、彩色图像作为秘密进行共享。     

一种动态(k,n)门限密钥托管方案

基于有限域上离散对数问题的难解性，给出了一种动态(k，n)门限密钥托管方案。该方案具有以下特点：(1)在更新系统密钥时，每个成员的子密钥可以不变。(2)可以任意增加、删除成员而不需要改变其它成员的子密钥。(3)是一种强壮的门限密钥托管方案。最后讨论了该方案的安全性、动态性和强壮性。     

On the security of a visual cryptography scheme for color images

Hou [Visual cryptography for color images, Pattern Recognition 36 (2003) 1619-1629] proposed a four-share visual cryptography scheme for color images. The scheme splits a dithered eight-color secret image into four shares: the black mask and other three shares. It was claimed that without knowing the black mask, no information about the secret image can be obtained even if all the other three shares are known. In this paper, we show that this may be true for a few specific two-color secret images only. In all other cases, however, security cannot be guaranteed. We show that an attacker can compromise a randomly chosen two-color secret image from any two of the other three shares with probability by completely recovering the shape and pattern of the secret image. The advantage will increase to if all the three shares are known. If the secret image has three or four colors, we show that the attacker can compromise it with probability and , respectively. Finally, we show that our technique can be extended to compromising secret images with more than four colors.     

一个新的广义(k,n)-门限密钥方案

1979年,Shamir提出的(k,n)-门限密钥分散管理的概念使密钥管理更加安全灵活。但这一方案也有其不完善之处,因为在现实中参与密钥管理的人在系统中所处的地位不尽相同,有许多活动必须要求某些特定的群体参与才能进行。该文考查了此类情形,将(k1,n1;k2,n2;…;k1,n1)-门限方案加以推广,提出了更为一般的k-(k1,n1,k2,n2;…;k1,n)-门限方案及其实现方法。     

On the security of a copyright protection scheme based on visual cryptography

With copyright protection in mind, the robustness property of a new scheme is always one of main concerns. However, to claim robustness of watermarking techniques is meaningful only when the false positive probability is taken into consideration as well as robustness benchmark. In this paper, the security of a robust copyright-protection scheme based on visual cryptography proposed by Lou et al. is analyzed. We show that the false alarm of their scheme is not neglectable. Precisely, it is insecure since the verification watermark can be unreasonably extracted from other unprotected images using the identical secret key by the owner. The main weak design will be proved and shown by means of giving theoretical analysis and conducting some counter experiments.     

(n,k)-冒泡排序网络的子网络可靠性

并行计算机系统互连网络的拓扑性质对系统功能的实现起着重要的作用.为了精确度量基于(n,k)-冒泡排序网络构建的并行计算机系统的子网络容错能力,建立了(n,k)-冒泡排序网络中(n-m,k-m)-冒泡排序子网络与特定字符串之间的一一对应关系,研究了点故障模型下(n,k)-冒泡排序网络中(n-m,k-m)-冒泡排序子网络的...     

Matching preclusion for the (n,k)-bubble-sort graphs

The matching preclusion number of a graph is the minimum number of edges whose deletion results in a graph that has neither perfect matchings nor almost-perfect matchings. In this paper, we find this number for the (n, k)-bubble-sort graphs and classify all the optimal solutions.     

A novel approach for verifiable (n,n) audio secret sharing scheme

Multimedia Tools and Applications - Audio is a natural way of communication among persons. Nowadays, many cases of Phone-tapping, hacking of E-mail having some audio files have been reported....     

k元n维冒泡排序网络的子网排除

在并行计算机系统中,元器件和线路故障普遍存在,而系统的容错能力可以通过其底层基础网络的拓扑性质衡量。为了精确度量以k元n维冒泡排序网络为底层拓扑结构的并行计算机系统的容错能力,结合其层次结构和子网划分特征,分别提出了节点故障模型和线路故障模型下攻击该网络中所有k－m元n－m维冒泡排序子网络的算法,确定了需要攻击的最优节点集合和最优线路集合。根据算法可得:当2≤k≤n－2,m≤k－1时,攻击k元n维冒泡排序网络中所有的k－m元n－m维冒泡排序子网络,在节点故障模型下需要攻击至少C^m_nm!个节点,在边故障模型下需要攻击至少C^m_nm!条线路。     

Verifiable quantum (k, n)-threshold secret sharing

In a conventional quantum (k, n) threshold scheme, a trusted party shares a quantum secret with n agents such that any k or more agents can cooperate to recover the original secret, while fewer than k agents obtain no information about the secret. Is the reconstructed quantum secret same with the original one? Or is the dishonest agent willing to provide a true share during the secret reconstruction? In this paper we reexamine the security of quantum (k, n) threshold schemes and show how to construct a verifiable quantum (k, n) threshold scheme by combining a qubit authentication process. The novelty of ours is that it can provide a mechanism for checking whether the reconstructed quantum secret is same with the original one. This mechanism can also attain the goal of checking whether the dishonest agent provides a false quantum share during the secret reconstruction such that the secret quantum state cannot be recovered correctly.