基于骑士巡游的灰度图像加密压缩算法

为了进一步提高涉密图像的存储和传输效率,提出了基于骑士巡游的灰度图像加密压缩算法。该算法将原始图像进行8×8分块,对每个块进行DCT变换,构建以块为单位的系数块化矩阵,然后采用骑士巡游置乱对该系数块化矩阵加密,对置乱加密后图像进行JPEG压缩得到加密压缩图像。实验仿真和分析表明,该算法密钥空间大、密钥敏感性高,在保证一定置乱度的前提下,获得了更高的压缩效率。     

基于分形和骑士巡游的图像压缩加密算法研究

将分形编码和骑士巡游相结合,提出一种基于分形和骑士巡游的图像压缩加密算法。首先用骑士巡游产生的路径作为密钥,路径用矩阵表示,矩阵中的每一元素与图像分形编码中的每个值域块相对应。然后按照骑士巡游的路径,从某个元素开始依照某个步长的顺序进行分形编码,为保证图像质量可以进行四叉树分裂。解码是其逆过程。用MATLAB对该算法进行仿真实验,测试了置乱度、密钥敏感性,在保证一定解码图像质量的情况下,压缩比优于JPEG。     

适用于付费数字电视的视频加密方案

将广义骑士巡游与视频加密相结合,提出了一种新的视频加密方案.将原始视频每8帧划分为一个视频片断,把各个视频片断按照帧平面分解为三维空间的广义棋盘,并提出4种方案,通过骑士的跳动置乱加密视频片断,从而达到视频加密的目的.实验结果表明,该方案加密效果好,加密效率高.而且,加密视频视觉质量可控性强,满足安全性要求,在付费数字电视节目播放等方面上具有广阔的应用前景.     

基于量子密钥分发和像素置乱的图像加密方法研究

鉴于当前经典图像加密算法的局限性及量子密钥分发协议无条件安全的特性,提出一种基于量子密钥分发和像素置乱的图像加密方法。首先通信双方产生量子密钥序列,然后将密钥序列转换成与要加密的图像对应的像素矩阵,将该像素矩阵与对应的图像的像素矩阵元素按位进行异或运算,再利用下一量子密钥序列生成像素置乱矩阵,对图像像素进行置乱变换,最终完成加密。解密方用与发送方相反的方法进行像素位置复原,再利用密钥矩阵进行异或运算即可解密。该算法所有密钥均采用量子密钥分发协议产生,安全性高,实现简单,经实验仿真证明,加密后的图像直方图呈均匀分布,像素相关性非常弱,像素变化率和信息熵高。     

基于摩尔型CA置乱的DCT域数字水印技术

利用具有混沌特性的摩尔型元胞自动机(Cellular Automata,CA)对原始水印图像进行置乱加密,接着将原始载体图像进行8×8分块离散余弦变换(DCT),按预定顺序读取低频和中频系数构成与水印图像同尺寸的系数矩阵,并在该系数矩阵的奇异值分解域中完成已加密水印信息的嵌入.仿真结果表明,该算法不仅具有良好的不可见性,而且对常见攻击如JPEG压缩、滤波、噪声和几何攻击等具有较强的稳健性,在版权保护领域具有一定的应用价值.     

基于混沌映射的数字图像置乱方法

文章提出了一种应用混沌映射在空间域对数字图像进行置乱的方法,在加密中利用分段线性映射由密钥生成混沌序列,然后以该序列为参数用面包师映射对图像矩阵置乱,其解密算法是加密算法的逆过程,实验显示该算法对图像加密具有良好的效果。     

锯齿空间填充曲线耦合压缩感知的彩图灰度化实时加密算法

针对当前彩色图像加密算法都是对RGB分量中所有像素加密,无法避免对次要像素的加密,使其加密效率较低,且加密后仍为彩色密文,增大了传输负载等不足。对此,本文提出了锯齿空间填充曲线耦合压缩感知的单通道彩图RGB分量灰度化实时同步加密算法。设计锯齿空间填充曲线,提高图像像素置乱率;嵌入压缩感知,对彩图RGB三分量进行同步压缩,得到三个测量矩阵,并构造灰度化函数,将图像演变为灰度图像;基于感兴趣区域原理,设计感兴趣像素提取方案,获取灰度图像的感兴趣像素矩阵,使其只扩散感兴趣像素,大幅度降低了像素扩散数量;设计加密函数,扩散感兴趣像素矩阵,再将加密像素映射到置乱图像相应位置,获取灰度密文。仿真结果显示:本文算法高度安全,能够得到灰度密文;与其他彩色加密算法相比,该算法具有更高的加密效率,可满足实时加密要求。     

基于压缩感知和变参数混沌映射的图像加密

为了减少加密图像的存储和传输负担,提出基于压缩感知(CS)和变参数控制混沌映射的图像加密算法。算法采用变参数控制混沌映射产生的测量矩阵对图像进行观测,选用与测量矩阵非相干的离散余弦变换(DCT)矩阵为稀疏基矩阵,使得压缩和加密同时完成。为了进一步提高加密算法的安全性,引入扰动因子使得加密算法的密钥与明文相关。同时,加密系统具有抗差分攻击的能力。另外,执行耦合的置乱扩散操作,使得置乱和扩散同时完成,更进一步增强了系统的安全性。加密图像的每个像素以8bit整型的形式输出便于数据的存储、显示和传输。实验结果表明,本文的加密算法是有效的和安全的。     

基于FPGA的视频图像加密系统的设计与实现

随着可编程逻辑器件的发展,FPGA的应用为高速数字视频图像处理提供了新的解决方案。文章的视频图像加密系统是基于Altera公司DE2-70开发平台设计实现的。系统主要由图像的采集输入模块、图像的加密处理模块和图像显示输出模块三个模块组成。对Arnold变换和骑士巡游变换两种视频图像加密算法的对比分析,选定了基于Arnold变换和骑士巡游变换相结合的复合置乱加密算法对视频图像进行加解密处理。在NiosIIIDE环境下对算法进行编程并调试。     

基于小波变换域的图像加密技术研究

如何确保基于网络的图像/视频信息的安全,是当前信息处理技术领域的亟待解决的难点和研究热点之一。本文利用混沌映射的随机性以及不可预测性,产生混沌序列矩阵对变换矩阵系数进行调整,再对系数进行置乱处理,然后利用信息隐藏技术对密钥进行隐藏,实现图像信息的高强度加密。仿真实验结果表明:该方法在不增加图像数据量的情况下,能够快速实现图像信息混沌复合加密,加密强度高、破解困难,恢复图像与原图像一致性良好,加密图像的抗干扰和抗压缩性能优良。     

P2P参考模型研究

The security of critical data is an important issue for distributed storage system design, especially for long-term storage. ESSA (An Efficient and Secure Splitting Algorithm for Distributed Storage Systems) is presented, which takes advantage of a two level information dispersal scheme to strengthen the security of data. In ESSA, the approach of knight’s tour problem, which is NP-Complete, is introduced to scramble data at the first level, and a split cube is used to split scrambled data at the second level. Thus, it is very difficult for the malicious user to get information because the task of reconstructing the original data needs more computation than they can tolerate. We prove that the security of ESSA is better than encryption algorithm and not inferior to erasure codes and secret sharing. Experimental results show that distributed storage systems exploiting ESSA has greater efficiency than that exploiting keyed encryption, erasure codes and
secret sharing     

ESSA: 一种高效安全的分布式存储系统数据拆分算法

The security of critical data is an important issue for distributed storage system design, especially for long-term storage. ESSA (An Efficient and Secure Splitting Algorithm for Distributed Storage Systems) is presented, which takes advantage of a two level information dispersal scheme to strengthen the security of data. In ESSA, the approach of knight’s tour problem, which is NP-Complete, is introduced to scramble data at the first level, and a split cube is used to split scrambled data at the second level. Thus, it is very difficult for the malicious user to get information because the task of reconstructing the original data needs more computation than they can tolerate. We prove that the security of ESSA is better than encryption algorithm and not inferior to erasure codes and secret sharing. Experimental results show that distributed storage systems exploiting ESSA has greater efficiency than that exploiting keyed encryption, erasure codes and
secret sharing     

基于DCT的彩色图像水印算法

提出了一种基于DCT的彩色图像水印算法,通过修改彩色图像绿色分量的DCT系数实现水印的嵌入。原始二值水印图像经Arnold置乱加密后,嵌入到绿色分量的DCT中频系数中,并能够根据原始图像提取出来。实验证明,该算法能有效抵抗JPEG压缩、裁剪、加噪、图像增强等攻击,具有良好的不可感知性和很强的鲁棒性。     

随机相位光学防伪中的前向迭代算法

本文采用的前向迭代算法用在随机相位光学仿伪中获得加密图象的Ｋｉｎｏｆｏｒｍ。该算法迭代过程中不再与被加密的原始图象进行比较,而是用加密图象振发布的均匀性控制迭代,这就克服了后向算法固有的局限性,在不增大每步迭代计算量的前提下,能够同时近代获得一对实际存在最佳加密相位列阵和加密图象的Ｋｉｎｆｏｒｍ不仅如此,整个算法的收敛速度比后的向算法快一个数量级,而且无论迭代结果的解密图象质量还是抑制能力也能明显     

A novel hybrid image encryption–compression scheme by combining chaos theory and number theory

Compression and encryption are often performed together for image sharing and/or storage. The order in which the two operations are carried out affects the overall efficiency of digital image services. For example, the encrypted data has less or no compressibility. On the other hand, it is challenging to ensure reasonable security without downgrading the compression performance. Therefore, incorporating one requirement into another is an interesting approach. In this study, we propose a novel hybrid image encryption and compression scheme that allows compression in the encryption domain. The encryption is based on Chaos theory and is carried out in two steps, i.e., permutation and substitution. The lossless compression is performed on the shuffled image and then the compressed bitstream is grouped into 8-bit elements for substitution stage. The lossless nature of the proposed method makes it suitable for medical image compression and encryption applications. The experimental results shows that the proposed method achieves the necessary level of security and preserves the compression efficiency of a lossless algorithm. In addition, to improve the performance of the entropy encoder of the compression algorithm, we propose a data-to-symbol mapping method based on number theory to represent adjacent pixel values as a block. With such representation, the compression saving is improved on average from 5.76% to 15.45% for UCID dataset.     

基于RICE的遥感多光谱图像无损压缩算法

目前应用于遥感多光谱图像的无损压缩算法复杂度较高,不利于硬件实现.针对这一不足,这里根据遥感多光谱图像的成像特点,提出一种采用可逆的分量变换(RCT)对谱段信息重新分配,再利用优化的RICE算法对图像数据进行编码的无损压缩算法.实验表明,该算法所采用的分块计算k值、预测器预测和改进的熵编码器较原RICE熵编码器更适于硬件实现,且该算法复杂度低,执行效率高,更好地满足了星载图像无损压缩的要求.     

基于JPEG压缩不变量和数字水印的图像认证方法

提出一种抗JPEG压缩的图像认证算法。根据图像不同块中位置相同的DCT系数之间的大小关系在JPEG压缩之后几乎没有发生变化这一性质,对图像进行分析生成特征编码,并将特征编码加密后以水印方式嵌入图像。认证时只需将待测图像的特征编码与从中抽取出的解密水印进行比较,利用篡改矩阵鉴别是否有内容被篡改,并给出具体的篡改位置。实验结果表明,该算法有很好的抗JPEG压缩性能,并可有效地检测出恶意篡改及其发生的位置。     

Image representation using block compressive sensing for compression applications

The emerging compressive sensing (CS) theory has pointed us a promising way of developing novel efficient data compression techniques, although it is proposed with original intention to achieve dimension-reduced sampling for saving data sampling cost. However, the non-adaptive projection representation for the natural images by conventional CS (CCS) framework may lead to an inefficient compression performance when comparing to the classical image compression standards such as JPEG and JPEG 2000. In this paper, two simple methods are investigated for the block CS (BCS) with discrete cosine transform (DCT) based image representation for compression applications. One is called coefficient random permutation (CRP), and the other is termed adaptive sampling (AS). The CRP method can be effective in balancing the sparsity of sampled vectors in DCT domain of image, and then in improving the CS sampling efficiency. The AS is achieved by designing an adaptive measurement matrix used in CS based on the energy distribution characteristics of image in DCT domain, which has a good effect in enhancing the CS performance. Experimental results demonstrate that our proposed methods are efficacious in reducing the dimension of the BCS-based image representation and/or improving the recovered image quality. The proposed BCS based image representation scheme could be an efficient alternative for applications of encrypted image compression and/or robust image compression.     

一种新的小波分形变换图像编码算法

提出了一种基于平滑双正交小波和自适应分割算法的小波域分形图像编码算法，在基于离散有限方差(DFV)最优准则下得到了适合图像编码的一种新的平滑双正交小波，从而改善了分块效应。在小波域的分形编码中，提出了一种基于图像信息分布特征的自适应分割算法，实验表明，该文算法在相同压缩比的情况下，解码图像的主观视觉质量和峰值信噪比都明显优于SQS方法、基本分形图像编码方法和SPIHT方法。