基于几何方法的双服务器口令认证与密钥协商

为了在保持口令认证系统代价低、易于使用等特点的同时,克服其单点失效、易受字典攻击等缺陷,提高其安全性,提出了基于几何方法的双服务器口令认证与密钥协商.用户口令分解为两个具有随机分布特性的子口令交付于两个服务器,由两个服务器共同完成口令认证,并同步协商会话密钥.口令认证协议中消息的形成与交换,采用几何方法代替基于离散对数难题等公钥技术.分析表明,用户口令、会话密钥是安全的;协议中只含模加与模乘运算,运算简单、快速.     

Stability of a two-class two-server retrial queueing system

We consider a two-class two-server retrial queueing system. Customers of each class arrive according to a Poisson process and the service times of each class of customers are assumed to be exponentially distributed with service rates depending on both the customer’s class and the servers. We provide stability and instability conditions for this retrial queueing system.     

A generating-function analysis of multiprogramming queues

A simple MP system consisting of an input-output facility and a central processor is modeled as a two-parameter Markov chain. The conditions for stability are demonstrated, and the steady-state joint probabilities are calculated explicitly. Various priority and capacity assignments result in radically different analytical situations, some of which have been considered in the literature. The present work treats a version that was considered for a time intractable. This paper emphasizes the analytical properties of the probability-generating functions and a method to solve a resultant functional equation. The numerical results display the importance of dependence between variables in the model.Technical Report No. 83, TECHNION—Israel Institute of Technology, Computer Science Department (August 1976).