Keyed hash function based on a chaotic map

Secure hash functions play a fundamental role in cryptographic and Web applications. They are mainly used, within digital signature schemes, to verify the integrity and authenticity of information. In this paper, we propose a simple and efficient keyed hash function based on a single chaotic map. Theoretical and simulation results demonstrate that the suggested scheme satisfies all cryptographic requirements of secure keyed hash functions such as strong confusion and diffusion capability, good collision resistance, high sensitivity to message and secret key, etc. Furthermore, it is fast and can be easily implemented through software or hardware. Moreover, the length of the hash value is flexible without any impact on the algorithm. This function is shown to have better statistical performance than many existing hash functions. Thus, the suggested hash function seems to be a good candidate as a secure keyed hash function for use in cryptographic applications.     

基于双混沌映射的文本hash函数构造*

提出了一种基于混沌Logistic 映射和斜帐篷映射的文本hash函数算法。该算法将明文信息分组并转换为相应的ASCII码值,然后把该值作为Logistic映射的迭代次数,迭代生成的值作为斜帐篷映射的初始值进行迭代,然后依据一定的规则从生成值中提取长度为128 bit的hash值。通过仿真对该算法的单向性、混乱与扩散、碰撞等性能进行分析,理论分析和仿真实验证明该算法可以满足hash函数的各项性能要求。     

基于Logistic与标准映射的数字图像加密算法

基于Logistic和标准映射,提出了新的数字图像加密算法。首先利用离散混沌系统初值敏感性、参数敏感性和具有白噪声统计特性的特点,结合Logistic映射和标准映射设计了置乱变换系统,这种置乱是依赖于密钥的。接着通过一种替代变换使置乱后图像的像素灰度值改变并产生互相依赖,即将每一像素值扩散到其它像素中去。这样,加密算法便具有置乱、替代、扩散等加密系统的基本要素。实验仿真和分析表明,该算法密钥空间大,易于实现,有较好的加密效果和统计特性。     

A novel image cipher based on mixed transformed logistic maps

In this paper, a novel secure cryptosystem is proposed for direct encryption of color images, based on transformed logistic maps. The proposed cipher provides good confusion and diffusion properties that ensures extremely high security due to the mixing of colors pixels. The encryption scheme makes use of six odd secret keys and chaotic keys for each operation. The operations include initial permutation of all pixels with six odd keys, nonlinear diffusion using first chaotic key, xoring the second chaotic key with resultant values and zig-zag diffusion with third chaotic key. The proposed scheme supports key sizes ranging from 192 to 400 bits. The security and performance of the proposed image encryption technique have been analysed thoroughly using statistical analysis, key sensitivity analysis, differential analysis, key space analysis, entropy analysis and performance analysis. Results of the various types of analyses are showing that the proposed image encryption technique is more secure and fast and hence suitable for the real-time applications.     

基于并行和变参数的混沌hash函数的构造与性能分析*

提出了一种基于可并行和变参数的混沌分段线性映射hash函数算法。该函数通过明文扩展将并行处理的明文消息矩阵元素信息关联起来,实现了并行性。由矩阵元素位置标号决定的可变参数和矩阵元素相应的ASCII码值分别作为混沌分段线性映射的输入参数和迭代次数来生成相应明文的中间hash值。最终的128 bit的hash值由中间hash值的异或而得到。计算机模拟表明,本算法具有较好的单向性、混乱、扩散性以及抗碰撞性,满足单向hash 函数的各项性能要求。     

基于消息网络的Hash函数构造

为了提高Hash函数的敏感性和运算速度,利用明文通过某种规则构造权重网络,并建立权重网络与混沌复杂动态网络的映射关系。将权重网络的邻接矩阵用到混沌系统中,经过特定量的迭代运算,将本次的输出对称交换后作为下个消息块运算的输入,类似的处理所有的消息块,最后的输出经过线性变换和进制转换,得到一定长度的Hash值,其长度与网络的大小有关。理论分析和数值仿真表明,提出的算法具有良好的初值敏感性、单向性、置乱性和强的抗碰撞性。     

A new fast double-chaotic based Image encryption scheme

In this paper, a new scheme for image encryption based on a double chaotic pseudo random generator (DCPG), simple XOR and shift rotations operations is proposed. The DCPG is a combination of both Tent and Chebyshev chaotic and so it needs three values of control parameters which are used as shared secret keys. The encryption consists of two rounds. In the first round, the hash value of the input image is computed using SHA-512. This value also is used as a forth shared secret key and from which, 4 amounts of the shift rotations are extracted. A pseudorandom sequence is generated using the proposed DCPG with the same size of the input image. This sequence and also the input image are divided into blocks of size 1?×?8. Each block of input image is processed with the corresponding block of the pseudorandom sequence using simple shift rotation and XOR operation. To extend the effect of the original image one pixel change to all the pixels of the cipher image, a second round of XOR operation is added. The proposed scheme has many advantages. It is highly secure due to two reasons. Firstly, it uses four secret keys for encryption which provides a large key space to overcome all types of brute force attacks. Secondly, the amounts of shift rotation used are input image dependent which achieves a strong resistance against chosen plaintext attacks. Also, it is more efficient compared to other recently existing schemes as it consists only of two rounds of simple operations. Security analysis of scheme has been provided. Based on the results, our scheme is highly secure with a reduced encryption time and so it can be used for many applications which require real time secure image communications.

     

使用双向耦合映像格子改进的并行混沌Hash函数

针对一种并行混沌Hash函数只能单向扩散以及低维混沌系统所存在的一些问题,提出使用双向映像格子进行改进的并行时空混沌Hash函数。该函数在消息矩阵组间采用并行结构,在组内采用迭代次数与矩阵元素值成负相关的双向耦合映像格子模型,该模型中的格子映射为参数值随矩阵元素位置而变化且迭代次数等于当前元素值的Kent映射,并行计算得出各分组中间值,最后异或各分组中间值得出最终Hash值。仿真实验表明,算法既提高了Hash的初值敏感性、混乱和扩散性,又拥有高效的并行性。     

Security of robust generalized MQV key agreement protocol without using one-way hash functions

The MQV key agreement protocol has been adopted by IEEE P1363 Committee to become a standard, which uses a digital signature to sign the Diffie–Hellman public keys without using any one-way hash function. Based on the MQV protocol, Harn and Lin proposed a generalized key agreement protocol to enable two parties to establish multiple common secret keys in a single round of message exchange. However, the Harn–Lin protocol suffers from the known-key attack if all the secret keys established are adopted. Recently, Tseng proposed a new generalized MQV key agreement protocol without using one-way hash functions. Tseng claimed that the proposed protocol is robust since the new protocol can withstand the forgery attack and the known-key attack. In this paper we show that this protocol is not secure since the receiver can forge signatures. We also propose an improved authenticated multiple-key agreement protocol, which is secure against the forgery attack and the known-key attack.     

基于Arnold变换的图像分存加密方法

为提高图像分存加密的安全性,提出一种将置乱加密、分存技术和像素扩散相结合的分存加密方法。首先,利用一维Logistic混沌映射产生Arnold变换的参数;其次,利用变参数的二维Arnold变换对图像进行像素位置置乱;最后,利用变参数的三维Arnold变换对置乱后图像进行像素值扩散并分存为两幅图像。实验结果表明,该方法的外部密钥敏感度较强,具有良好的雪崩效应,能够有效地抵抗明文和差分等攻击,且解密密钥与明文图像紧密相关。     

Hash key-based image encryption using crossover operator and chaos

This paper proposes a color image encryption scheme using one-time keys based on crossover operator, chaos and the Secure Hash Algorithm(SHA-2). The (SHA-2) is employed to generate a 256-bit hash value from both the plain-image and the secret hash keys to make the key stream change in each encryption process. The SHA-2 value is employed to generate three initial values of the chaotic system. The permutation-diffusion process is based on the crossover operator and XOR operator, respectively. Experimental results and security analysis show that the scheme can achieve good encryption result through only one round encryption process, the key space is large enough to resist against common attacks,so the scheme is reliable to be applied in image encryption and secure communication.     

Image encryption and compression based on the generalized knight’s tour,discrete cosine transform and chaotic maps

An efficient and simple encryption and compression scheme for digital image is reported in this paper. This scheme is based on the algorithm of the generalized knight’s tour, discrete cosine transform and non-linear chaotic maps. In this scheme, according to the structure of compression, confusion and diffusion are attained by methods of the generalized knight’s tour and chaotic maps. Firstly, the generalized knight’s tour algorithm is utilized to scramble the pixels while the data correlation preserved. Then, the chaotic system is used to generate a pseudorandom permutation to encrypt the part of coefficients from discrete cosine transform for diffusion. Experimental results show that the proposed scheme can gain robust security and a high compression ratio, which indicates that the proposed scheme is practicable.

     

基于明文相关的混沌映射与SHA-256算法数字图像的加密与监测

针对数字图像的传播安全性问题,以及数字图像加密脱离明文、过分依赖混沌系统的问题,提出了基于明文相关的混沌映射与SHA-256算法数字图像的加密与监测算法。算法通过使用SHA-256算法计算明文图像的哈希值,作为摘要来监测数字图像的传播;使用前向扩散、关联明文的置乱与后向扩散的方法对数字图像进行加密,Lorenz混沌映射产生相应的密码。结果表明该算法具有较好的抵抗各种攻击的能力,达到了图像传播的安全性与隐蔽性的目的。     

基于量子混沌映射的高效安全的图像加密算法

提出了一种基于带密钥的广义Arnold变换和量子混沌映射的图像加密算法。首先,利用二维Logistic映射产生初始条件和参数;其次,利用带密钥的广义Arnold变换对彩色图像的像素值进行置换;最后将初始条件和参数代入到量子混沌系统中,由该系统产生的一系列伪随机数与图像的像素值进行异或,改变各个位置的像素值,进而达到加密的效果。为了提高加密系统的复杂性和随机性,二维Logistic映射和二维量子混沌映射都结合加权耦合映像格子以运用到加密系统中。     

基于双混沌动态参数的单向散列算法

结合双混沌系统以及传统散列函数的优点,提出一种新的带密钥单向散列函数的构造方法。该方法将帐篷映射和Logistic混沌映射结合组成双混沌系统生成混沌序列,作为动态参数代替传统散列算法中的固定参数参与轮函数的运算并生成散列摘要。结果表明,所提方法具有较大的密钥空间,很好的单向性,初值和密钥敏感性。     

Symmetric keys image encryption and decryption using 3D chaotic maps with DNA encoding technique

In present digital era, multimedia like images, text, documents and videos plays a vital role, therefore due to increase in usage of digital data; there comes high demand of security. Encryption is a technique used to secure and protect the images from unfair means. In cryptography, chaotic maps play an important role in forming strong and effective encryption algorithm. In this paper 3D chaotic logistic map with DNA encoding is used for confusion and diffusion of image pixels. Additionally, three symmetric keys are used to initialize 3D chaos logistic map, which makes the encryption algorithm strong. The symmetric keys used are 32 bit ASCII key, Chebyshev chaotic key and prime key. The algorithm first applies 3D non-linear logistic chaotic map with three symmetric keys in order to generate initial conditions. These conditions are then used in image row and column permutation to create randomness in pixels. The third chaotic sequence generated by 3D map is used to generate key image. Diffusion of these random pixels are done using DNA encoding; further XOR logical operation is applied between DNA encoded input image and key image. Analysis parameters like NPCR, UACI, entropy, histogram, chi-square test and correlation are calculated for proposed algorithm and also compared with different existing encryption methods.

     

一种新的基于双混沌系统的图像加密方案

提出了一种新的基于双混沌系统的图像加密方案。把Chen’s系统和Logistic映射结合起来产生随机性更加良好的三维混沌密钥序列,并从密钥序列中通过采样提取出新的用于加密的序列。提出了图像置乱算法和替代加密算法,利用Logistic映射产生的一维混沌序列来实现像素位置的置乱,像素值加密算法采用按分组进行加密和二次加密来对像素值进行加密。通过实验测试表明：算法具有良好的像素值混淆和扩散性能,有较强的抗统计攻击的能力和足够大的密钥空间,加密图像像素值具有类随机均匀分布特性,且相邻像素具有零相关特性。这些结果表明了所提出方案有很高的安全性。     

对“改进遍历矩阵和像素值扩散的图像加密算法”的密码分析

最近提出了一个基于混沌的改进遍历矩阵和像素值扩散的图像加密算法,该加密算法首先将Logistic混沌映射构造一个遍历矩阵用于在图像空域迭代置换,然后再采用一个新的混沌序列对像素值进行扩散。通过对该加密算法的分析,找出了该算法存在的安全漏洞,从而提出了选择明文/已知明文的攻击方法,通过选择特殊的明文图像及其对应的密文图像,可在未知密钥的条件下对同样大小的密文图像进行破解。仿真实验结果表明这种攻击方法非常有效。     

整合ChaCha20哈希运算的分块扩散自适应图像加密算法

目的 针对数字图像网络传输安全性和混沌加密算法自适应差的问题,提出一种基于ChaCha20哈希运算的分块扩散自适应图像加密算法(BDCH)。方法 BDCH算法首先通过分段线性混沌映射(PWLCM)产生的混沌序列填充明文图像,使其成为方形图像;其次,利用初始输入密钥及明文图像总和,通过ChaCha20哈希运算生成8×8的初始哈希矩阵,并与PWLCM混沌映射生成的伪随机序列作用,联合产生哈希密钥矩阵,PWLCM的迭代初值选取为初始密钥矩阵均值、初始密钥及明文图像归一化均值;然后,利用Arnold和PWLCM映射同步置乱扩散整幅图像,并分成互不重叠的8×8大小图像块;最后,采用哈希密钥矩阵对图像块进行两轮扩散,完成图像加密。结果 灰度及彩色图像的计算机仿真与性能分析表明,BDCH算法的信息熵、峰值性噪比、密钥敏感性指标优于其他加密算法,并且解决了直接使用初始哈希矩阵会产生的弱密钥问题,密钥空间大。结论 结合同步置乱扩散和哈希密钥矩阵非线性分块扩散的BDCH算法可有效抵抗各种攻击,安全性高、自适应性强,适合各种类型的灰度及彩色图像加密,潜在应用价值大。     

基于高维混沌系统组合的图像加密新算法

提出了一种基于高维混沌系统组合的图像加密算法。该算法首先利用广义猫映射对图像进行置乱,然后利用Lorenz系统对置乱后的图像进行替代变换。研究结果表明,该算法具有良好的像素值混淆、扩散性能和较大抵抗强力攻击的密钥空间,加密图像像素值具有类随机均匀分布特性,且相邻像素的值具有零相关特性。这些结果表明所提出的方案具有较高安全性。