多模式多变量公钥密码体制

针对量子计算机对公钥密码体制的挑战,提出一种能抵抗量子算法的多模式多变量公钥密码算法。量子计算机在解决多变量多项式问题并无高效算法,在传统多变量公钥密码体制的基础上,使用多分支模式,在分支内部采用加模式、减模式和迭代模式,增强了多变量公钥密码体制的安全性。通过分析各种常见攻击的复杂度,多模式多变量公钥密码体制能有效抵抗各种攻击,可以应用于加解密、签名和数据完整性验证。     

Logistic混沌扰动三角形密码体制

针对多变量三角形体制不能抵抗线性攻击的问题,结合多变量密码体制与混沌理论建立混沌扰动多变量三角形体制。建立Logistic混沌映射的同步系统,并将Logistic映射在有限域上离散化。通过在三角形体制中增加Logistic混沌扰动,改变多变量三角形密码体制的中心映射的结构,消除多变量三角形体制的中心映射方程组之间存在的线性关系。通过理论分析证明提出的Logistic混浊扰动三角形密码体制能抵抗线性化攻击,提高了Jonquières体制的安全性。     

立方多变量公钥密码体制的最小秩分析

立方加密体制是经典的多变量公钥密码体制Square的改进方案,其中心映射由平方映射改为了立方映射,由此将公钥多项式从二次提升到三次来抵抗针对二次多变量公钥密码体制的最小秩攻击。针对这种体制,提出一种结合差分的最小秩攻击,旨在恢复它的私钥。首先,分析体制的中心映射差分,并根据差分后的结构来确定它的秩;然后,求解公钥差分,并提取二次项的系数矩阵;接着,由系数矩阵以及确定的秩构造一个最小秩问题;最后,结合扩展的Kipnis-Shamir方法对问题进行求解。实验结果表明,利用最小秩攻击可以恢复立方加密体制的私钥。     

一种基于MPKC的新型签名方案

多变量密码体制(MPKC)被认为是能够抵御基于量子计算机攻击的新型公钥密码体制之一.利用减扰动方法构造出了一种基于MPKC的新型签名方案,其计算效率,主要指中心映射求逆的效率要高于两个著名的多变量签名体制Sflash[1]和Quartz[2].给出了对该方案安全性分析,它能够抵抗现有的针对多变量密码体制的三类攻击.     

一种混合多变量公钥签名方案

多变量公钥密码体制能抵抗量子计算机的攻击,是后量子时代一种安全的密码体制备选方案.考虑到Square体制可有效抵抗线性化攻击,不能抵抗差分攻击,三角型密码系统能抵抗差分攻击,但受到线性化方程攻击和最小秩攻击的情况,结合Square体制和三角型密码系统,采用新的混合签名结构框架重构中心映射,提出一种混合多变量公钥签名方案.分析结果表明,混合签名方案克服了Square体制和三角型密码系统的缺陷,能够抵抗线性攻击(包含一般线性化方程攻击和高阶线性化方程攻击)、差分攻击、最小秩攻击和代数攻击,具备较高的安全性.     

一类具有安全加密功能的扩展MQ公钥密码体制

量子计算机的发展,对目前广泛应用的传统公钥密码体制(如RSA,ECC等)构成了严重的威胁.MQ公钥密码是目前抗量子计算密码领域中最为活跃的热点研究课题之一,但是目前MQ公钥密码只能用于签名,很难构造出安全的加密算法.同时,随着近年来多个MQ签名算法相继被攻破,人们对MQ类公钥密码体制的安全性产生了质疑.本文通过引入Hash认证技术、并结合传统MQ公钥密码算法,提出了一种扩展MQ公钥密码体制,它可看作是对传统MQ公钥密码算法结构的本质拓展.利用本文引入的Hash认证技术可有效地提升MQ签名算法的安全性,同时也可据此设计出安全高效的MQ公钥加密方法.     

一种基于多变量的代理签名方案

文章针对量子计算机可能带来的危机,重点分析了用多变量公钥密码体制(MPKC)作为能够抵御未来基于量子计算机攻击的候选者之一.文章结合多变量的性质,尝试使用有限域上的二次多变量多项式构造代理签名体制,利用多变量同构问题(IP),选取以Rainbow结构的多项式作为中心映射,并且基于安全性的考虑,在签名方案基础上增加了秘密仿射变换的性质,使公钥多项式并非像其在原模型当中一样为私钥的直接合成,而是隐藏部分私钥,减少攻击者获得的信息量,同时签名验证是对中间过程某结果的验证,提出了一个基于多变量签名体制的代理保护型签名方案.     

公钥密码技术

1 公钥密码的起源 公钥密码算法(也称双钥密码算法)是非对称的密码算法,即其密钥分为公钥和私钥,因此被称为公钥密码体制,其公钥可以公开。公钥密码技术的出现,给密码的发展开辟了新的方向。公钥密码技术虽然已经历了20多年的研究,但仍具有强劲的发展势头,在认证系统和密钥交换等安全技术领域起着关键的作用。 在传统密码体制(也称对称密钥密码体制)中,     

多变量密码体制下大型布尔矩阵生成算法

大型可逆布尔矩阵在多变量公钥密码体制设计中有着其广泛用途,而高效的大型可逆布尔矩阵生成算法直接影响多变量公钥密码体制设计的质量。利用线性变换的思想,提出了布尔矩阵B_8n*12n的一种生成算法,具有简单有效的优点。并给出了该大型布尔矩阵生成算法的具体描述,分析了该算法的时间复杂度,密钥的存储空间。整个求解过程和结果表明该算法的有效性。最后给出了其逆矩阵的求解算法。     

基于混沌载体的Lorenz—RSA可控混沌数字签名

指出公钥密码数字签名无法阻止拷贝攻击这一缺陷产生的原因。通过将信息载体纸张中纤维混沌图像与RSA公钥算法相结合,给出一种可抵御对明文和数字签名拷贝攻击的数字签名方法。通过将Lorenz混沌算法与RSA公钥算法相结合,改进私钥计算方法,设计出一种可以控制私钥数字的混沌公钥密码算法。     

A symmetric image encryption scheme based on hybrid analog-digital chaotic system and parameter selection mechanism

In recent years, various chaos-based image encryption algorithms have been proposed to meet the growing demand for real-time secure image transmission. However, chaotic system that is the core component of chaos-based cryptosystem usually degrades under finite computing precision, causing many security issues. In this paper, a novel cryptosystem with analog-digital hybrid chaotic model is proposed. Firstly, the analog Chen chaotic system and the digital Logistic map are adopted to depict the capability of the hybrid model, in which analog system is used to perturb digital system. Dynamic analyses demonstrate that the hybrid method has better complexity, larger chaotic parameter range and good ability to counteract dynamical degradation. The chaos-based key streams generated by the perturbed Logistic map are more suitable for image encryption. Secondly, a parameter selection mechanism is introduced to increase security. The state variables of Chen chaotic system and cipher image are involved in parameter selection process to dynamically change the parameter of the perturbed Logistic map. The involvement of cipher image makes the key streams relevant to plain image and can resist known/chosen-plaintext attacks. Performance, security and comparison analyses indicate that this cryptosystem has high security, low time complexity, and ability to resist common attacks.

     

多变量体制下的代理签密方案

目前大多数代理签密方案的安全性主要是基于传统密码体制下的,随着量子计算技术的发展,传统密码体制下的代理签密方案受到严重威胁,构造抗量子计算的代理签密方案具有重要意义。多变量公钥密码是抗量子计算密码的主要候选者之一,鉴于此,提出多变量密码体制下的代理签密方案,利用有限域上求解非线性多变量多项式方程组问题和多项式同构问题保证了其安全性。分析表明新方案计算速度快、通信代价低,并具有抗量子计算的能力。     

Chaos based cryptosystem for still visual data

Recent years have witnessed a strong relationship between chaos and cryptography. Owing to this relationship, development in one field directly impacts the other field. High computational resources are consumed in re-designing of the complete cryptosystem due to a newly developed chaotic map. Also, the tools developed to discern chaos leads to easy cryptanalysis of chaotic cryptosystems. To save resources and overcome easy cryptanalysis, this paper proposes a spatial domain based chaotic cryptosystem that employs different chaotic maps during permutation-substitution process. Multiple iterations have been performed to achieve resistance against various cryptanalytic and error function attacks, that are specifically designed for chaos based cryptosystems. The proposed technique has been generalized and verified for different chaotic maps. A significant benefit of the proposed cryptosystem is its support for chaotic system free property, which allows replacement of an existing chaotic map with a different map at a later stage. Thorough performance, security and comparative analysis ascertains efficacy of the proposed technique.     

一种利用外键控制的密文反馈混沌分组密码算法研究

近年来，基于混沌理论的保密通信和数据保密得到广泛、深入的研究，提出了许多基于混沌理论的混沌加密算法，但这些算法缺乏可靠的安全性和鲁棒性。本文提出一种利用外键控制的密文反馈混沌分组密码算法，其最大的优点是系统的密钥由128位的外部键生成，混沌系统的系统参数、初始条件和迭代的次数随着密文反馈动态生成。这样，密码系统的随机性、复杂性得到了极大的提高。同时理论和实验表明，该算法具有较高的安全性和鲁棒性，能够抵抗差分和线性密码分析。     

基于改进Logistic映射的混沌图像加密算法

经典Logistic映射存在系统参数范围受限、混沌序列分布不均等问题。对Logistic映射进行改进并将其应用于图像加密中,设计一种置乱与扩散同时操作的图像加密算法。对经典Logistic映射增加模运算并对其所生成序列进行二进制比特重排,利用改进Logistic映射生成具有更好混沌特性的伪随机序列并用于加密系统的置乱和扩散阶段。将所生成的伪随机矩阵与明文图像矩阵进行异或操作以实现明文图像预加密。在此基础上,采取置乱与扩散同时操作的策略以置乱和扩散预加密后的图像从而得到密文图像。安全性分析及实验结果表明,该算法具有良好的加密性能和安全性,可以抵抗暴力攻击、差分攻击等常见攻击。     

对一类迭代混沌分组密码的分析与改进

用选择明文攻击的方式对一种基于迭代混沌映射的加密算法进行了分析,并提出了相应的改进算法.在改进算法中,子密钥序列以密文反馈和从混沌映射中抽取数据相结合的方式产生,使子密钥序列在保持良好的均匀分布和随机统计特性的同时,还与明文相关,有效地增强了算法的安全性.最后对设计加密算法中应注意的问题进行了分析和总结.     

A spatiotemporal chaotic image encryption scheme based on self adaptive model and dynamic keystream fetching technique

This paper proposes a block chaotic image encryption algorithm based on self-adaptive and dynamic key stream fetching technique (DKSFT) which makes use of a non-adjacent spatiotemporal chaotic system coupled with Tent-Sine system (NASC-TSS) for the chaotic orbit generation. The chaotic dynamics of NASC-TSS has incredible cryptographic properties contrasted with the existing 1D chaotic map. Firstly, a bit-level permutation strategy based on circular-shift operation is suggested which focuses to lessen the implications propelled by the classical permutation architectures. Finally, in the block based diffusion phase, a control parameter is designed to update the initial condition of the employed chaotic system. Subsequently, a unique keystream is generated for various plain-image processing which in turn elevates the complexity of breaking the proposed algorithm under known attacks. Furthermore, the pixel handling in both the permutation and the diffusion stages are done with DKSFT in which the keystream selection corresponds to the pixel position of the permutated-image. The adopted strategies such as self adaptive model and DKSFT can keep up the characteristics of the keystream fluctuating and dodge different sorts of attacks, undoubtedly the known-plaintext and chosen plaintext attacks. The investigation outcomes against a series of rigorous security analysis shows that the strong execution of the proposed cryptosystem against various attacks. These highlight an appealing security level with just a single round of encryption operation, making the algorithm impeccably appropriate for some unique interactive media applications.     

基于改进型Henon映射的快速图像加密算法

为了解决传统Henon映射在密码系统中实现时混沌空间小和安全性低的缺陷,设计了一种改进型Henon映射。通过分岔图、混沌轨道、Lyapunov指数和近似熵分析表明改进型的Henon映射具有更大的混沌空间、更好的遍历性和更高的混沌复杂度,使其更加适用于设计安全的密码系统。基于改进型的Henon映射,提出了一种快速图像加密算法,该算法由多级块置乱和双向块扩散过程构成。在多级块置乱过程,明文图像被分成几个大小不等的图像块,然后对图像块进行置乱操作。在双向块扩散过程,置乱后的图像重新被分成若干个大小相同的图像块,最后对图像块进行块扩散操作得到密文图像。仿真结果和安全性分析表明该算法是安全高效的。     

A new efficient medical image cipher based on hybrid chaotic map and DNA code

In this paper, we propose a novel medical image encryption algorithm based on a hybrid model of deoxyribonucleic acid (DNA) masking, a Secure Hash Algorithm SHA-2 and a new hybrid chaotic map. Our study uses DNA sequences and operations and the chaotic hybrid map to strengthen the cryptosystem. The significant advantages of this approach consist in improving the information entropy which is the most important feature of randomness, resisting against various typical attacks and getting good experimental results. The theoretical analysis and experimental results show that the algorithm improves the encoding efficiency, enhances the security of the ciphertext, has a large key space and a high key sensitivity, and is able to resist against the statistical and exhaustive attacks.