一种共享份分块构造的异或区域递增式视觉密码方案

该文依据授权子集的个数将共享份划分若干块,按照共享份分块构造的设计思路,结合(n, n)异或单秘密视觉密码的加密矩阵,构造了异或区域递增式视觉密码的秘密分享与恢复流程。与现有方案相比,该方案可以实现解密区域图像的完全恢复,且明显减小了共享份的大小。     

一种新的多秘密分享视觉密码

 本文给出了一种新的多秘密分享视觉密码的定义,能够支持多授权子集和共享份操作.基于区域标记和单秘密视觉密码的基础矩阵,设计了多秘密分享与恢复的流程,给出一种实现方案.最后对方案的有效性进行了理论证明和实验验证.     

异或视觉密码的理想存取结构研究

该文给出异或视觉密码的理想存取结构的定义,分析了其特征,研究了理想存取结构的共享份构造方法。在此基础上,提出将通用存取结构划分为若干个理想存取结构的算法,设计了通用存取结构的秘密分享与恢复流程。与现有的方案相比,该方案实现了秘密图像的完全恢复,且明显地减小了共享份的规模。     

（k，n）异或视觉密码的一般性研究

通过研究(k, n)异或视觉密码像素扩展度最优的必要条件,该文提出一种由基矩阵生成(k, n)异或视觉密码的方法,并从理论上证明了该方法适合2相似文献   

基于压缩算法的存取式多秘密视觉密码

依据多幅秘密图像的像素组合与基矩阵之间的映射关系,该文分析了目前存取式多秘密视觉密码存在的冗余基矩阵问题,提出了一种减小基矩阵规模的压缩算法.该算法以一列像素为处理单元,且满足秘密图像的整体对比性.在此基础上,设计了新的存取式多秘密视觉密码的秘密分享与恢复流程.与现有的方案相比,该方案能够有效减小共享份的尺寸,且对于简单图像的压缩效果更加明显.     

多重门限的图像秘密共享方案

 针对传统的基于视觉密码的图像秘密共享方案存在像素扩张导致其只能共享小尺寸的秘密图像、信息隐藏效率较低的问题,提出一种能够提高信息隐藏容量的(t,k,n)多重门限图像秘密共享方案.该方案利用秘密图像信息控制视觉密码方案中共享矩阵的选取,从而实现秘密图像在视觉密码方案中的隐藏.在秘密图像恢复的第一阶段,任意t个参与者直接叠加其影子图像后可以视觉解密出低质量的秘密图像信息;在第二阶段,任意k个参与者可以从影子图像中提取出隐藏的信息,并通过计算恢复出精确的灰度秘密图像.相对于传统的视觉密码方案,本文方案在不影响视觉密码恢复图像的视觉质量前提下,可以隐藏更多的秘密图像信息,而像素扩张尺寸较小.     

一种无损多秘密分享视觉密码方案

针对分享多幅秘密图像存在信息损失的问题,该文给出(n, n)无损多秘密分享视觉密码的定义,在此基础上基于环状共享份设计了一种(n, n)多秘密视觉密码方案,使秘密图像的信息损失为零。实验结果表明,该方案不仅实现了在多个参与者之间分享多幅秘密图像,而且秘密图像能够完全恢复。     

视觉密码方案概述

视觉密码(VC)是一种用于分享秘密图像的加密方案,与传统的密码技术相比具有简单性、安全性、隐蔽性等优点。其加密是将图像编码为分享,将分享打印在透明胶片上或以数字形式存储;其解密过程是对分享进行叠加,然后通过人类的视觉能力来实现。本文介绍了视觉密码的基本概念和各种不同的视觉密码方案,以及每种方案中使用的技术。此外,对视觉密码在不同领域上的应用做出了说明。     

基于视觉密码的DWT-SVD水印技术

本文提出基于视觉密码的数字水印技术,利用像素不扩展的(2,2)视觉密码方案,将秘密图像拆分成两个与秘密图像等大小的分享份图像,把两个分享份图像利用DWT-SVD水印算法嵌入到载体图像中,最后利用数字水印的提取算法,将两个分享份图像提取出来,进行叠加恢复秘密图像.基于视觉密码提取出来的分享份不会泄露秘密信息的任何内容,从而保证了秘密信息的安全性.实验结果表明,此方案可以抵抗常见的攻击行为.     

每次处理2个像素像素扩展度为1的(2,2)视觉密码方案

为了解决传统视觉密码像素扩展度高的问题及分存图像占用存储空间过大问题,提出每次处理2个像素像素扩展度为1的(2,2)视觉密码方案.方案中,秘密图像为黑白二值图像,每次处理2个像素,得到的2个分享份额图像为黑白噪声图像,叠加分享份额恢复秘密图像.该方案解密过程简单,恢复秘密图像无变形,像素扩展度为1.     

Sharing more information in gray visual cryptography scheme

Visual cryptography scheme (VCS) shares a binary secret image into several binary shadows, and the secret image can be visually revealed by stacking qualified shadows without computation. From the point of view of sharing secret information, VCS is not efficiency because of the large size expansion and low visual quality. In this paper, we introduce a general gray visual cryptography scheme, which can share more information, called Sharing More Information Gray Visual Cryptography Scheme (SMIGVCS). All the shadow pixels of VCS embed additional information to generate gray shadows of SMIGVCS, and the embedded information comes from the shadows of a polynomial-based secret sharing scheme (PSSS). In the revealing process, a vague secret image is visually decoded by stacking qualified shadows, and more information is revealed by computation. Compared with the two-in-one image secret sharing scheme (TiOISSS), our SMIGVCS can achieve smaller shadow size with acceptable visual quality.     

HP-VCS: A high-quality and printer-friendly visual cryptography scheme

Visual Cryptography Scheme (VCS) is a secret-sharing scheme which aims to encrypt a secret message into multiple shares and transmit them to participants over an untrusted communication channel. Although human vision can easily reveal the secret message by stacking a sufficient number of shares, this scheme reduces the visual quality of recovered images. This paper presents a novel high-quality and printer-friendly VCS. When providing high-quality recovery, this scheme keeps the size of the shares the same as the secret image. Experimental results show that, compared with previous work, the proposed scheme significantly improves the performance of recovered images.     

Voronoi-based image representation applied to binary visual cryptography

A common processing scheme of Visual Cryptography (VC) consists of generating two ciphered images from a secret image. The sender transmits these key images via two different channels. The receiver collects the key images and recovers the secret image by superimposing them. In this article, Voronoi tessellation is exploited in Visual Cryptography for the first time to the best of our knowledge. The proposed Voronoi-based Visual Cryptography (VVC) technique permits to drastically reduce the amount of encoded and transmitted information by comparison with a traditional VC scheme. Hence, the technique can be used for transmissions of secret images with enforcement of the transmission reliability by enhancing the redundancy of information or with communication networks and technologies having low bandwidth and memory. Moreover, the random arrangement of the Voronoi polygons makes the transmission of the secret image more secure since the sender and the recipient use a private generator of random points. In addition, shape reconstruction properties of the image-based Voronoi representation are stated.     

基于累积矩阵的可防欺骗视觉密码方案

该文基于累积矩阵提出一种可防止欺骗的视觉密码方案,在不泄露秘密信息的前提下,不需要其他额外信息,可发现多个独立欺骗者的存在,及时阻止欺骗行为。与以往方案相比,该方案构造更为简单,能发现更多的欺骗者。     

(t,k, n) XOR-based visual cryptography scheme with essential shadows

Visual cryptography scheme (VCS) shares a binary secret image into multiple shadows, only qualified set of shadows can reveal the secret image by stacking operation. However, VCS suffers the problems of low visual quality of the revealed image and large shadow size. A (t, k, n) XOR-based visual cryptography scheme (XVCS) shares the secret image into n shadows including t essentials and n-t non-essentials. A qualified set of shadows contains any k shadows including t essentials. The revealing process is implemented by XOR operation on the involved shadows. In this paper, we propose a construction method for (t, k, n)-XVCS with essential shadows. The secret image can be revealed perfectly, and the shadow size is small compared with VCS. Theoretical analysis and experimental results show the security and effectiveness of the proposed scheme.     

基于随机网格的视觉多秘密共享方案

为了提高视觉秘密共享(VSS)的恢复效果,该文提出一种基于随机网格的视觉多秘密共享方案.通过使用一种基于圆柱面的随机网格阈值多秘密图像共享方案,使得用户一次可以共享多个秘密图像;部分份额图像受到篡改仍然可以恢复秘密图像,具有较好的鲁棒性;同时份额的数量和最后恢复图像的视觉质量成正相关.仿真结果表明所提出的多秘密视觉共享...     

A Visual Secret Sharing Scheme for Progressively Restoring Secrets

Visual secret sharing has received more and more attention over the past years due to the fact that neither complex computation nor cryptographic knowledge is required to decrypt the secret image directly according to the characteristics of the human vision system. Considering the issue of sharing the secret image at multiple image resolutions with the meaningful shadows, in this paper, we present a friendly progressive visual secret sharing scheme without expanding the image size in the shadows and the reconstructed secret image based on applying a 22-sized block-wise operation to generate the shadows block by block. The proposed method can achieve these benefits: 1) the generated shadows are meaningful, and their sizes are not expanded, and 2) the secret image can be recovered at different resolutions by stacking different quantities of shadows together. The experimental results also show that the proposed method is superior to other compared schemes.     

Implementation of TiOISSS with meaningful shadows and with an additional authentication image

Visual Cryptography Scheme (VCS) is a cryptographic technique for protecting secret images. The advantage of using VCS is that decoding can be done without use of any computations. Nevertheless, the reconstructed image has poor visual quality. Therefore, Two in One Image Secret Sharing Scheme (TiOISSS) was proposed which takes the advantage of VCS and provides good quality decoded images. However, the existing TiOISSS has security limitations as it is implemented only for noisy shadows. Hence, in this paper, modified TiOISSS is proposed and implemented for meaningful shadows. To enhance the security of the shares and prevent fake shares that may be introduced by hackers, an authentication image is shared along with the secret image. The quality of the reconstructed image is improved by using adaptive halftoning technique. Experimental results demonstrate the improved security and quality by the proposed scheme.