演化密码对抗差分密码分析能力的研究

演化密码是我国学者提出的一种新型密码体制.本文对演化密码对抗差分密码分析的能力进行了研究,研究表明演化密码对抗传统差分攻击的能力高于普通固定算法密码.本文在分析差分攻击的数据复杂度,最佳差分特征概率,比特优势以及预期成功率关系的基础上,证明了比特优势和预期成功率相同时,攻击演化密码的数据复杂度大于攻击固定算法密码的数据复杂度;并证明了在数据复杂度和预期成功率相同的情况下,攻击演化密码的时间复杂度明显高于攻击固定算法密码的时间复杂度.这表明演化密码对抗传统差分攻击的能力高于固定算法密码.     

Addition Sequence Method of Scalar Multiplication of Elliptic Curve over OEF

A new elliptic curve scalar multiplication algorithm is proposed. The algorithm uses the Frobenius map on optimal extension field (OEF) and addition sequence. We introduce a new algorithm on generating addition sequence efficiently and also give some analysis about it. Based on this algorithm, a new method of computing scalar multiplication of elliptic curve over an ()EF is presented. The new method is more efficient than the traditional scalar multiplication algorithms of elliptic curve over OEF. The comparisons of traditional method and the new method are also given.     

Construction of Resilient Functions

Based on the relationship Between nonlinearity and resiliency of a multi-output function, we present a method for constructing nonintersecting linear codes from packing design. Through these linear codes, we obtain n-variable, moutput, t-resilient functions with very high nonlinearity. Their nonlinearities are currently the best results for most of cases.     

A New Proxy Signature Scheme with Message Recovery Using Self-Certified Public Key

A proxy signature scheme with message recovery using self-certified public key is proposed, which withstands public key substitution attacks, active attacks, and forgery attacks. The proposed scheme accomplishes the tasks of public key verification, proxy signature verification, and message recovery in a logically single step. In addition, the proposed scheme satisfies all properties of strong proxy signature and does not use secure channel in the communication between the original signer and the proxy signature signer.     

具有限制性的代理签名方案

针对现有的限制性代理方案尚不能有效地对时间和次数同时控制这个问题,基于一次性代理签名方案和前向安全技术,提出了一个新的具有次数和时间限制的代理签名方案。方案在离散对数和大数分解计算困难下是安全的,并且满足代理签名的所有性质。     

根据连续2n-1个状态写出单圈T函数ANF的方法

运用布尔函数的相关知识, 给出了根据单圈T函数的连续2^n-1个状态写出其代数标准型的一种方法.     

具有大2-adic与k错2-adic复杂度的周期序列

在密码学的流密码理论当中,2-adic复杂度、k错2-adic复杂度类似于其它复杂度测度,同样要具有较大的数值.文中借助数论中的中国剩余定理等相关理论研究了二元序列的2-adic复杂度与线性复杂度的关系,证明了具有最大2-adic复杂度以及较大k错2-adic复杂度的N周期序列的存在性,给出了具有这种性质的周期序列的数目的下界.以此种周期序列作为密钥流序列可以有效地抵抗穷举攻击.     

Provable Efficient Certificateless Group Key Exchange Protocol

Certificateless public key cryptography （CL-PKC） avoids the inherent escrow of identity-based cryptography and does not require certificates to guarantee the authenticity of public keys. Based on CL-PKC, we present an efficient constant-round group key exchange protocol, which is provably secure under the intractability of computation Diffie-Hellman problem. Our protocol is a contributory key exchange with perfect forward secrecy and has only two communication rounds. So it is more efficient than other protocols. Moreover, our protocol provides a method to design efficient constant-round group key exchange protocols and most secret sharing schemes could be adopted to construct our protocol.     

一类二值自相关序列族的构造方法

在扩频通信和密码学领域广泛使用的伪随机序列,人们不仅要求其具有很高的线性复杂度,而且要有良好的自(互)相关性能.长期以来,人们对伪随机序列的研究表明,目前仅有有限的几种序列具有理想的二值自相关特性,它们分别是:m序列、L序列、Hall序列和GMW序列.这些序列的数目是比较少的.在本文中,作者基于上述四种序列,构造出完全不同于上述序列族的二值自相关序列.由     

多精度整数高效模幂运算算法的研究

介绍了多精度整数求幂运算中的“滑动窗口”算法,并结合Montgomery约简算法．对“滑动窗口”算法进行了应用研究,分析了根据多精度整数的位数来确定相应的窗口大小。结果表明．采用这种组合的模幂运算算法具有十分高效的执行效率,4096位多精度整数的模幂计算大约需要1．5s,并可满足RSA的应用对密钥长度的安全需求。