改进的CBC 模式及其安全性分析

针对CBC模式在分块适应性攻击模型下不安全这一问题,提出了一个新的分组密码工作模式。新方案引进了Gray码,改变了原有模式的输入方式,打乱了前后输出输入的内在联系。同时,利用规约的思想对其安全性进行了分析。结果表明,在所用分组密码是伪随机置换的条件下,方案在分块适应性攻击模型下是可证明安全的。     

GMW序列和WG序列及WG序列间的互相关特性

对于奇数n,研究了Gordon-Mills-Welch（GMW）序列与Welch-Gong（WG）序列（及其某一采样序列）间的互相关函数以及WG序列间的互相关函数。研究表明：GMW序列与WG序列（及其某一采样序列）间的互相关函数以及WG序列间的互相关函数最终均与m-序列与其采样序列间的互相关函数相关;并且在一定条件下,WG序列间的互相关函数可为3-值或5-值的。另外,给出了GMW序列与WG序列间互相关函数的最大峰值。     

改进的无证书有序多重签名方案

A sequential multi-signature enabled multiple users to jointly sign a document in order.Xu,et al proposed a provably-secure certificateless sequential multi-signature scheme with constant signature length and pairing computations.However,it was shown that the scheme had a drawback in the verifying algorithm,and then it overcame the drawback.But,the efficiency of the corrected scheme was greatly reduced.An efficient certificateless sequential multi-signature scheme is constructed,and the multi-signature generated by proposed scheme consists of one group element and the verification algorithm requires only 2 bilinear pairings.     

Cryptanalysis and Improvement of Two GHZ-State-Based QSDC Protocols

In a recent paper[J. Korean. Phys. Soc. 49 （2006） 459], two GHZ-state-based quantum secure direct communication protocols were presented. Here we point out that an eavesdropper can utilize a special property of GHZ states, i.e. ＂correlation-elicitable＂ to obtain half information of the transmitted secrets without being detected in both protocols. The particular attack strategy is demonstrated in detail. Furthermore, a possible improvement is proposed, which makes the protocols secure against this kind of attack.     

高非线性度多输出布尔函数的构造

本文主要讨论了构造具有高非线性度多输出布尔函数的方法.对于输入变量个数少于输出变量个数的多输出布尔函数,我们给出了存在非零非线性度的充分必要条件及具体的构造方法.我们还利用一类特殊的多输出bent函数构造出具有非常高非线性度的无偏多输出函数.