一种节点信誉相关的P2P网络信任管理模型

现有的P2P系统中存在大量的欺诈行为和不可靠的服务.本文通过模拟社会关系网络中信任的形成机制,提出P2P网络信任管理模型TMMRN,TMMRN通过考察节点的信誉值来进行安全交易,节点的信誉主要来自于其他节点对它的加权信任反馈,在信誉计算中增加了激励机制.TMMRN还可减少交易时的网络负担.实验表明TMMRN可提高信誉值的计算效率,能有效抵抗恶意节点的攻击,还可激励懒惰节点主动参与到系统中来.     

无线传感器网络中的信任管理

作为对基于密码体系的安全手段的重要补充,信任管理在解决WSNSs(wireless sensor networks)中的内部攻击,识别恶意节点、自私节点及低竞争力节点,提高系统安全性、可靠性和公平性等方面有着显著优势.综述了WSNs环境下信任管理的特点、分类方法、框架设计、脆弱性分析、攻击模型及对策,在此基础上介绍了WSNs下的典型信任管理系统.以信任计算模型为中心的WSNs环境下信任管理框架的设计是信任管理系统的核心,从信任要素、信任计算模型和信任值的应用这3个方面对其进行了深入讨论.最后,总结了WSNs环境下信任管理的研究现状,提出了值得参考的研究发展方向.     

Mitigating information asymmetry to acquire venture capital financing for digital startups in China: The role of weak and strong signals

This paper addresses how weak and strong signals affect venture capital funding acquired by digital startups at their early stage in various industries of China. We also articulate the interaction mechanism of these strong and weak signals by demonstrating their complementary or substitutive effects in alleviating information asymmetry on startup quality, which can help digital startups secure venture capital financing. Drawing on signalling theory and institutional legitimacy theory, we introduce application (app) downloads as a novel strong signal that can reduce market legitimacy concerns, and previous-round venture capitalist reputation as a traditional strong signal that mitigates regulatory legitimacy concerns. We treat founders' startup and IT experience as weak signals, as they provide rhetorical and indirect information indicating a startup's potential to establish regulatory and market legitimacy. The study empirically investigates our hypotheses using data of 163 digital startups in various industries of China. Results confirm the positive relationships between strong signals and venture capital funding secured by a digital startup. Furthermore, signals of similar strength are found to complement each other's effects in certain situations, while strong signals can reduce the effects of weak signals on a digital startup's financing performance under specific conditions that create these mixed effects. Implications for digital startup research and practice as well as limitations and suggestions for future research are discussed.     

基于信誉机制的改进PBFT共识算法

针对实用拜占庭容错共识算法（practical Byzantine fault tolerant,PBFT）通信开销大和缺乏奖惩机制的问题,提出一种基于信誉机制的改进PBFT共识算法RPBFT（reputed practical byzantine fault tolerance）。首先,引入信誉机制对节点评分,将参与共识的节点分为收集器节点和普通共识节点,并对恶意节点进行惩罚。其次,收集器节点负责收集普通共识节点的投票消息,避免普通共识节点之间的通信,从而降低通信开销。最后,当普通共识节点中的拜占庭节点均无恶意行为时,通过增加收集所需的投票数量,减少一次投票收集过程,实现快速共识。实验结果表明,RPBFT能够有效地发现恶意节点并对其作出惩罚,同时具有更低的通信开销、平均共识时延以及更高的共识吞吐量。当节点总数为37时,与SBFT相比,RPBFT将平均共识时延降低25.2%以上,并将共识吞吐量提高39%以上。