一种基于Feistel结构和WTS的分组密码

AES为新的数据加密标准,通过研究分组密码算法加密的整体结构和AES加密算法,文中设计了一种基于Feistel结构和WTS策略的分组密码算法FWTS。 FWTS采用Feistel结构,轮函数借鉴AES的WTS策略,分组长度为256 bits,密钥长度为128 bits,192 bits,256 bits。通过依赖性测试表明,FWTS算法4轮充分满足雪崩效应、严格雪崩准则和完备性。通过不可能差分分析,FWTS算法的6轮不可能差分所需的时间复杂度要大于AES算法的6轮不可能差分的时间复杂度。FWTS算法的安全性不低于AES算法。通过效率测试表明FWTS的加密效率要高于AES。     

基于Feistel网络的十进制加密算法

提出一种基于Feistel网络的十进制加密算法。针对十进制数运算的特点,在加密算法中定义4种新的运算,在密钥扩展算法和解密算法中定义2种新的运算,并设计十进制S盒。将该算法应用于短分组加密仿真系统中,实验结果表明,该算法具有较好的密码学特性,加解密的各项扩散率指标均较优,经6轮加密后,该算法达到完全扩散。     

一类不平衡Feistel密码的安全性能分析

为评估一类不平衡Feistel密码的安全性能,通过列举的方法,对该密码抵抗差分密码分析和线性密码分析的能力进行了深入的研究。在轮函数是双射的假设条件下,证明了3,4,6,8,10,2r（r≥3）轮密码分别至少有1,1,3,4,5,r个轮函数的输入差分非零,从而若设轮函数的最大差分和线性逼近的概率分别为p和q,则2r（r≥3）轮密码的差分特征和线性特征的概率分别以pr和qr为上界。     

基于Feistel网络的AES密钥扩展算法

Rijndaes算法被美国国家标准技术研究所(NIST)定做分组密码标准后,在安全领域得到广泛的应用,并被随后的NESSIE工程直接吸纳为标准.但同时,由于AES应用的广泛性和基础性,对其的研究和分析,不可避免地成为一个热点.本文结合被NESSIE工程所提出的其他的分组密码算法,提出了一种新的密钥扩展算法,该算法基于一种变形的Feistel网络结构,并在Matlab平台上得以实现.最后分析和证明了和原有算法相比具有的速度效率和安全性能优势.     

基于超混沌序列的Feistel结构图像加密算法

为了更好地将传统的Feistel加密结构应用在图像加密中,将加密与混沌系统结合起来,在混沌图像加密的基础上,提出了一种基于超混沌序列和Feistel结构的图像加密算法。首先应用Kawakami映射产生的混沌预处理加密序列,对图像进行预处理加密;然后将Logistic映射生成的初始值代入Hyperhenon映射产生加密序列,由产生的混沌加密序列作为Feistel加密结构的S盒;最后,利用Feistel结构对图像进行加密。仿真加密算法的同时对算法的加密效果和安全性进行了分析,实验结果表明,该算法具有较高的稳定性、安全性和加密效率。     

Secure key-alternating Feistel ciphers without key schedule

Dear editor, Blockciphers play an fundamental role for cryptography in information security,which usually consist of round func-tions and key schedules.As one o...     

Quantum secret sharing for general access structures based on multiparticle entanglements

In this paper, we study the implementation of quantum secret sharing (QSS) schemes for general access structures rather than the threshold structure. Using multiparticle entanglements in high-dimensional system, three novel multipartite QSS formalisms for general access structures are proposed. The method of how to build general access structures in these formalisms is discussed. A major feature of these formalisms is that a variety of secret sharing schemes with different access structures can be constructed depending on the dealer’s wish. Besides, hierarchic and threshold authorized structures can also be built. All of which make our formalisms highly flexible.     

Quantum computing with spin qubits in semiconductor structures

We survey recent work on designing and evaluating quantum computing implementations based on nuclear or bound-electron spins in semiconductor heterostructures at low temperatures and in high magnetic fields. General overview is followed by a summary of results of our theoretical calculations of decoherence time scales and spin-spin interactions. The latter were carried out for systems for which the two-dimensional electron gas provides the dominant carrier for spin dynamics via exchange of spin-excitons in the integer quantum Hall regime.     

Quantum inferring acausal structures and the Monty Hall problem

This paper presents a quantum version of the Monty Hall problem based upon the quantum inferring acausal structures, which can be identified with generalization of Bayesian networks. Considered structures are expressed in formalism of quantum information theory, where density operators are identified with quantum generalization of probability distributions. Conditional relations between quantum counterpart of random variables are described by quantum conditional operators. Presented quantum inferring structures are used to construct a model inspired by scenario of well-known Monty Hall game, where we show the differences between classical and quantum Bayesian reasoning.     

Known-key distinguishers on type-1 Feistel scheme and near-collision attacks on its hashing modes

We present some known-key distinguishers for a type-1 Feistel scheme with a permutation as the round function. To be more specific, the 29-round known-key truncated differential distinguishers are given for the 256-bit type-1 Feistel scheme with an SP （substitution-permutation） round function by using the rebound attack, where the S-boxes have perfect differential and linear properties and the linear diffusion layer has a maximum branch number. For two 128-bit versions, the distinguishers can be applied on 25- round structures. Based on these distinguishers, we construct near-collision attacks on these schemes with MMO （Matyas- Meyer-Oseas） and MP （Miyaguchi-Preneel） hashing modes, and propose the 26-round and 22-round near-collision attacks for two 256-bit schemes and two 128-bit schemes, respectively. We apply the near-collision attack on MAME and obtain a 26-round near-collision attack. Using the algebraic degree and some integral properties, we prove the correctness of the 31-round known-key integral distinguisher proposed by Sasaki et al. We show that if the round function is a permutation, the integral distinguisher is suitable for a type-1 Feistel scheme of any size.     

使用压缩函数的非平衡Feistel结构的伪随机性和超伪随机性

从可证明安全的角度研究使用压缩函数的非平衡Feistel结构(UFN-C)的安全性,证明了k+1轮UFN-C是伪随机的,k+2轮UFN-C是超伪随机的;进一步地,探讨了UFN-C的有效构造,降低了Naor和Reingold在1999年文章中类似结构对伪随机函数个数的要求.最后,针对一类具体的UFN-C--SMs4,分析其广义形式SMS4-like结构的伪随机性和超伪随机性,为设计与使用该类结构的分组密码提供了可证明安全的理论依据.     

On the differential and linear efficiency of balanced Feistel networks

Balanced Feistel networks (BFN) have been widely used for constructing efficient block ciphers. They are known to provide high efficiency with respect to differential and linear cryptanalysis, when instantiated with SL-type round functions (BFN-SL). This work suggests that BFNs attain higher efficiency when the round function is defined as a composition of two substitution layers connected by a linear diffusion layer (SLS-type round function). The resulting structure is called BFN-SLS.Tight upper bounds on the differential and linear trail probabilities are proven for such constructions. When compared to BFN-SL with single-round diffusion, BFN-SLS exhibits an increase by almost 1/3 in the proportion of active S-boxes. When compared to BFN-SL with multiple-round diffusion, BFN-SLS provides the same proportion of active S-boxes, requiring, however, twice less linear operations and a single diffusion matrix for all rounds.It is argued that the cost of linear operations cannot be ignored when dealing with efficiency. Different BFNs are compared under consideration of the relative complexity of linear and nonlinear finite field operations. As a result, since BFN-SLS minimizes the number of necessary linear operations, its efficiency is higher than that of the known BFN-SL constructions.     

Analysis of 3-line generalized Feistel networks with double SD-functions

Generalized Feistel networks (GFN) are broadly employed in the design of primitives for block ciphers, stream ciphers, and hash functions. Lately, endowing the functions of GFNs with the structure of nonlinear substitution followed by linear diffusion (substitution-diffusion, SD) has received a great deal of attention. In this contribution, we prove tight lower bounds on the number of differentially and linearly active S-boxes for 3-line GFNs with double SD-functions where two SD-structures are applied one after another. We also show 8-round impossible differentials for 3-line GFNs with bijective functions. Moreover, we demonstrate that the proportion of active S-boxes in all S-boxes for such GFNs is by up to 14% higher than that for 4-line GFNs with double SD-functions, when instantiated with MDS matrices. This indicates that, rather surprisingly, the 3-line GFNs can be more efficient in practice than those with 4 lines.     

嵌套Feistel结构的SP型分组密码的可证明安全性

给出一个嵌套Feistel结构的SP型分组密码的模型及其抵抗差分密码分析和线性密码分析的可证明安全性,所获得的结果主要基于对SP型密码的可证明安全性的一个推广性结果的证明．依照模型,给出了一个具体的分组密码的例子．     

Feistel ciphers in East Germany in the communist era

Feistel ciphers (balanced and unbalanced) represent the most popular symmetric cipher type in modern cryptography. The invention of Feistel ciphers is usually credited to IBM’s Horst Feistel, who co-created the first publicly known encryption algorithm of this type, Lucifer, in the early 1970s. In this publication, the authors will show that Feistel ciphers (or at least a very similar concept) played a surprisingly important role in East Germany in the last two decades of the communism era (i.e., between 1970 and 1990). They will introduce four Feistel ciphers developed by East German cryptologists during these two decades. This includes an unbalanced Feistel cipher that predated RC2, the oldest unbalanced Feistel cipher known in the crypto community (by over a decade), as well as an East German DES variant.