Secure Multi-Party Computation without Agreement

It has recently been shown that authenticated Byzantine agreement, in which more than a third of the parties are corrupted, cannot be securely realized under concurrent or parallel (stateless) composition. This result puts into question any usage of authenticated Byzantine agreement in a setting where many executions take place. In particular, this is true for the whole body of work of secure multi-party protocols in the case that a third or more of the parties are corrupted. This is because these protocols strongly rely on the extensive use of a broadcast channel, which is in turn realized using authenticated Byzantine agreement. We remark that it was accepted folklore that the use of a broadcast channel (or authenticated Byzantine agreement) is actually essential for achieving meaningful secure multi-party computation whenever a third or more of the parties are corrupted. In this paper we show that this folklore is false. We present a mild relaxation of the definition of secure computation allowing abort. Our new definition captures all the central security issues of secure computation, including privacy, correctness and independence of inputs. However, the novelty of the definition is in decoupling the issue of agreement from these issues. We then show that this relaxation suffices for achieving secure computation in a point-to-point network. That is, we show that secure multi-party computation for this definition can be achieved for any number of corrupted parties and without a broadcast channel (or trusted pre-processing phase as required for running authenticated Byzantine agreement). Furthermore, this is achieved by just replacing the broadcast channel in known protocols with a very simple and efficient echo-broadcast protocol. An important corollary of our result is the ability to obtain multi-party protocols that remain secure under composition, without assuming a broadcast channel.     

A bandwidth latency tradeoff for broadcast and reduction

The “fractional tree” algorithm for broadcasting and reduction is introduced. Its communication pattern interpolates between two well known patterns—sequential pipeline and pipelined binary tree. The speedup over the best of these simple methods can approach two for large systems and messages of intermediate size. For networks which are not very densely connected the new algorithm seems to be the best known method for the important case that each processor has only a single (possibly bidirectional) channel into the communication network.     

校园智能公共广播系统改造升级实践

通过分析校园智能公共广播系统的功能及构成,指出了常州工程职业技术学院智能公共广播系统改造升级的必要性,提出了一个以原有设备和线路为基础的改造升级的方案。     

一种频率广播策略在短波组网中的应用

针对频率广播机制在短波组网中的弊端,比较了多种解决方案,提出了一种基于频率分时复用和反向动态唤醒的短波台站频率广播策略,为短波组网项目提供一种短波频率广播机制的实现方案。     

Performance of Broadcast and Multicast Service with Interference Cancellation Based on Macro Diversity

The cdma2000 1xEV-DO mobile communication system provides broadcast and multicast services(BCMCS) to meet an increasing demand for multimedia data services.Single frequency network(SFN) is recognized as an effective way to improve the spectral efficiency of the BCMCS system.To improve the coverage and the data rate of the BCMCS users,an interference cancellation algorithm based on macro diversity is introduced in this paper.The performance of BCMCS in CDMA2000 EV-DO networks under the condition of SFN is evaluated.The simulation results show a significant improvement in bit error ratio(BER) while quantitatively validating the efficiency of our approach.     

全固态立体声调频广播发射机原理和维修（三）

本文较全面地分析了调频发射机各部分的原理、电路、测量、安装、使用及维修技术,既有理论分析,更注重电路实践。文中还收集了不同电路方案,有关国家标准,故障分析,判断及排除经验。     

Resilient-optimal interactive consistency in constant time

For a complete network of n processors within which communication lines are private, we show how to achieve concurrently many Byzantine Agreements within constant expected time both on synchronous and asynchronous networks. As an immediate consequence, this provides a solution to the Interactive Consistency problem. Our algorithms tolerate up to (n-1)/3 faulty processors in both the synchronous and asynchronous cases and are therefore resilient-optimal. In terms of time complexity, our results improve a time bound of (for n concurrent agreements) which is immediately implied by the constant expected time Byzantine Agreement of Feldman and Micali (synchronous systems) and of Canetti and Rabin (asynchronous systems). In terms of resiliency, our results improve the resiliency bound of the constant time, -resilient algorithm of Ben-Or. An immediate application of our protocols is a constant expected time simulation of simultaneous broadcast channels over a network with private lines.Received: April 2001, Accepted: September 2002, Michael Ben-Or: Research supported by Israel Academy of Sciences and by United States - Israel Binational Science Foundation grant BSF-87-00082     

一种改进的监视Cache协议算法

本文探讨ＳＭＰ体系结构的多处理环境下,几种常见Ｃａｃｈｅ一致性问题的解决方案,讨论和对比了各自的特色,在此基础上进行一步分析了基中的不足,并提出我们的方案－－改进的监视Ｃａｃｈｅ协议算法。     

Techniques for pipelined broadcast on ethernet switched clusters

By splitting a large broadcast message into segments and broadcasting the segments in a pipelined fashion, pipelined broadcast can achieve high performance in many systems. In this paper, we investigate techniques for efficient pipelined broadcast on clusters connected by multiple Ethernet switches. Specifically, we develop algorithms for computing various contention-free broadcast trees that are suitable for pipelined broadcast on Ethernet switched clusters, extend the parametrized LogP model for predicting appropriate segment sizes for pipelined broadcast, show that the segment sizes computed based on the model yield high performance, and evaluate various pipelined broadcast schemes through experimentation on Ethernet switched clusters with various topologies. The results demonstrate that our techniques are practical and efficient for contemporary fast Ethernet and Giga-bit Ethernet clusters.     

我国广播电视网络经营与产业化发展思考

分析国内广播电视信息网络发展的现状及存在的问题,有针对性地提出经营和产业发展战略：实现全国网络互联,完善产业组织结构,调整和理顺广电运营结构,客观地分析把握住现实业务和挖掘市场潜在需求,多渠道吸引投资资金,建立广泛的战略合作伙伴关系,才能促使中国广播电视网络的高速产业化发展。