一类连续可分离背包问题的直接算法

对于一类带有单个线性约束以及盒约束的一般连续可分离二次背包问题给出了一种直接的算法,根据模型特有的结构,通过调节线性约束的拉格朗日乘子λ 的取值范围,以及在算法求解过程中通过判断目标函数一次项中的变量是否在盒约束范围内,来逐步确定所有变量的最优值, 并通过该算法得到的实验结果与其他算法的比较,说明了这种算法的可行性和有效性．     

无证书代理重签密方案

结合无证书密码体制和签密思想提出了一个无证书代理重签密方案,在方案中,使用一个半可信代理人实现了一个签密到另一个签密的透明转换.与其他相似方案相比,实现了签密的完全转换.一般情况下,在Alice的私钥和Bob的公钥下完成的签密经转换后只能用Alice的身份信息和Daddy的私钥解签密;在本文提出的方案中,由Alice的私钥和Bob的公钥完成的签密经转换后可以用Charlie的身份信息和Daddy的私钥解签密,且签密的验证不需要明文信息的直接参与.基于间隙双线性Diffie-Hellman问题,在随机预言机模型下,证明了可以抵抗无证书代理重签密中的第一类攻击.     

General Quantum Meet-in-the-Middle Search Algorithm Based on Target Solution of Fixed Weight

Similar to the classical meet-in-the-middle algorithm, the storage and computation complexity are the key factors that decide the efficiency of the quantum meet-in-the-middle algorithm. Aiming at the target vector of fixed weight, based on the quantum meet-in-the-middle algorithm, the algorithm for searching all n-product vectors with the same weight is presented, whose complexity is better than the exhaustive search algorithm. And the algorithm can reduce the storage complexity of the quantum meet-in-the-middle search algorithm. Then based on the algorithm and the knapsack vector of the Chor-Rivest public-key crypto of fixed weight d, we present a general quantum meet-in-the-middle search algorithm based on the target solution of fixed weight, whose computational complexity is ∑_j^d=(0(√C_n-k+1^d-j)+O(C_k^jlogC_k^j)) with ∑_i=0^dC_kⁱ memory cost. And the optimal value of k is given. Compared to the quantum meet-in-the-middle search algorithm for knapsack problem and the quantum algorithm for searching a target solution of fixed weight, the computational complexity of the algorithm is lower. And its storage complexity is smaller than the quantum meet-in-the-middle-algorithm.     

基于遗传算法求解背包问题的算法探讨

将遗传算法应用于背包问题,利用遗传算法的求解思想,对传统的背包问题进行了详细的分析,按照遗传算法的基本结构设计了编码,并通过实例验证了遗传算法用于解决背包问题的可行性和有效性.     

基于双线性对的无证书并行多重签名方案

针对目前无证书多重签名方案在计算效率、通信成本和安全性等方面存在的问题,提出一种基于双线性对的无证书多重签名方案,并模拟3种不同类型的攻击者,分析新签名算法的不可伪造性.该方法基于无证书短签名的思想,构造签名长度较短的并行多重签名方案.仿真实验表明,与目前已有的方案相比,新方案降低了签名的通信成本和计算量,因此更适合于资源受限的网络环境.     

A Multi-Period Renewal equipment problem

This paper looks at a Multi-Period Renewal equipment problem (MPR). It is inspired by a specific real-life situation where a set of hardware items is to be managed and their replacement dates determined, given a budget over a time horizon comprising a set of periods. The particular characteristic of this problem is the possibility of carrying forward any unused budget from one period to the next, which corresponds to the multi-periodicity aspect in the model. We begin with the industrial context and deduce the corresponding knapsack model that is the subject of this paper. Links to certain variants of the knapsack problem are next examined. We provide a study of complexity of the problem, for some of its special cases, and for its continuous relaxation. In particular, it is established that its continuous relaxation and a special case can be solved in (strongly) polynomial time, that three other special cases can be solved in pseudo-polynomial time, while the problem itself is strongly NP-hard when the number of periods is unbounded. Next, two heuristics are proposed for solving the MPR problem. Experimental results and comparisons with the Martello&Toth and Dantzig heuristics, adapted to our problem, are provided.     

二次剩余密码体制的安全性分析

对基于二次剩余问题的密码体制进行安全性分析 ,利用 Morrison- Brillhart素因子分解算法 ,设计一种新的有效的攻击方法。在新的攻击方法下 ,上述基于二次剩余问题的密码体制是不安全的。论文最后给出设计安全的、基于二次剩余问题的密码体制的基本原则     

利用时空混沌同步进行数字加密通信

提出一种利用时空混沌同步的计算机网络数字加密通信方案,并用软件实现了语音双工实时密码通信.在该方案中,收、发端两个单向耦合映射格点(OCOML)系统被同一混沌信号所驱动而达到同步,其时空混沌输出信号分别用作加密和解密的密钥序列,OCOML的耦合参数为系统的主密钥.系统的主要优点是传输效率高,便于用软件实现实时通信,且通信的安全性获得了改善. 关键词： 时空混沌同步 密码系统 传输效率     

基于RSA体制的数字移动通信系统用户认证方案

设计了一种基于RSA体制的数字移动通信系统的用户身份认证方案.其安全性基于大整数的分解难题,能抵抗包括网内攻击的多种攻击.用户请求采用预计算的方式,有效减少了实时计算量,满足移动通信系统中用户请求的实时性要求.与基于离散对数的方案相比,本方案用户端和网络中心的计算量与存储量少,能高效实现连续请求.理论分析表明:本方案安全性高,计算复杂性和通信量低,网络中心存储量低,符合数字移动通信系统要求.     

A TTP-Independent Watermarking Protocol Based on Commutative Cryptosystem for Copyright Protection in E-Commerce

For the purpose of deterring unauthorized duplication and distribution of multimedia contents in e-commerce, some Buyer-seller watermarking protocols which combine of traditional watermarking and fingerprinting techniques have been proposed, However, previous protocols have potential risk from trust third party （TTP） because all entities （including multi-buyers and multi-sellers） mentioned in protocol construct a star tupology like connection, in which the watermark certification authority （WCA） serves as the central point in the interaction and therefore its availability probably turns out to be the vital bottleneck of reliability and efficiency to the whole system. Secondly, WCA holds entire information about watermark used hy Buyers so that an innocent Buyer can he found as guilty if WCA collude with the Seller. In this paper, we propose a watermarking protocol to address the problems using cryptographic technologies in phase of watermark generation. The resuh is a TTP-independent and collusion-secure buyer-seller watermarking protocol.