Blockchain-Based Key Management Scheme Using Rational Secret Sharing

Traditional blockchain key management schemes store private keys in the same location,which can easily lead to security issues such as a single point of failure.Therefore,decentralized threshold key management schemes have become a research focus for blockchain private key protection.The security of private keys for blockchain user wallet is highly related to user identity authentication and digital asset security.The threshold blockchain private key management schemes based on verifiable secret sharing have made some progress,but these schemes do not consider participants’self-interested behavior,and require trusted nodes to keep private key fragments,resulting in a narrow application scope and low deployment efficiency,which cannot meet the needs of personal wallet private key escrow and recovery in public blockchains.We design a private key management scheme based on rational secret sharing that considers the self-interest of participants in secret sharing protocols,and constrains the behavior of rational participants through reasonable mechanism design,making it more suitable in distributed scenarios such as the public blockchain.The proposed scheme achieves the escrow and recovery of personal wallet private keys without the participation of trusted nodes,and simulate its implementation on smart contracts.Compared to other existing threshold wallet solutions and keymanagement schemes based on password-protected secret sharing(PPSS),the proposed scheme has a wide range of applications,verifiable private key recovery,low communication overhead,higher computational efficiency when users perform one-time multi-key escrow,no need for trusted nodes,and personal rational constraints and anti-collusion attack capabilities.

Supply Chain Network Equilibrium with Revenue Sharing Contract under Demand Disruptions

Contract is a common and effective mechanism for supply chain coordination,which has been studied extensively in recent years.For a supply chain network model,contracts can be used to coordinate it because it is too ideal to obtain the network equilibrium state in practical market competition.In order to achieve equilibrium,we introduce revenue sharing contract into a supply chain network equilibrium model with random demand in this paper.Then,we investigate the influence on this network equilibrium state from demand disruptions caused by unexpected emergencies.When demand disruptions happen,the supply chain network equilibrium state will be broken and change to a new one,so the decision makers need to adjust the contract parameters to achieve the new coordinated state through bargaining.Finally,a numerical example with a sudden demand increase as a result of emergent event is provided for illustrative purposes.

Modeling China's offshore production sharing contracts using meta analysis

Production sharing contracts have been used in the development of China’s offshore petroleum resources since 1982, but the mechanism in which the fiscal terms impact project economics is complicated and not well understood. The purpose of this paper is to model China’s offshore production sharing contracts using a probabilistic approach. Cash flows and economic indicators are used for a typical offshore oilfield development, and meta-models are constructed to analyze the basic features of the fiscal system. Applications of the models in contract negotiation are discussed.

Production sharing contract: An analysis based on an oil price stochastic process

Assuming that oil price follows the stochastic processes of Geometric Brownian Motion （GBM） or the Mean-Reverting Process （MRP）, this paper takes the net present value （NPV） as an economic index and models the PSC in 11 different scenarios by changing the value of each contract element （i.e. royalty, cost oil, profit oil as well as income tax）. Then the NPVs are shown in probability density graphs to investigate the effect of different elements on contract economics. The results show that under oil price uncertainty the influence of profit oil and income tax on NPV are more significant than those of royalty and cost oil, while a tax holiday could improve the contractor＇s financial status remarkably. Results also show that MRP is more appropriate for cases with low future oil price volatility, and GBM is best for high future oil price volatility.

Revenue-sharing contract to coordinate independent participants within the supply chain

To improve the performance of the supply chain with one supplier and multiple retailers under deterministic price-sensitive customer demand, an optimal strategy is proposed based on knowledge discovery. First the decentralized system in which the supplier and the retailers are independent, profit-maximizing participants with the supplier acting as a Stackelberg game leader is studied. Numerical examples illustrate the importance of the coordination. The conventional quantity discount mechanism needs to be modified to coordinate the supply chain, so a revenue-sharing contract is proposed to coordinate such supply chain. Lastly, a special decision under certain demand rates is studied. The pricing and replenishment policies can be decided sequentially, which yields much less loss comparing with optimal decision when the demand rates are sufficiently large.

Study of the Option Ordering Policy concerning Perishable Farm Produce Based on Revenue Sharing Contract

This paper considers the two-echelon supply chain system which consists of single agricultural producers and retailers,and analyzes the impact of sharing ratio on the option ordering quantity,and retailers and producers' expected profits.Studies have shown that in the case of decentralization,when the revenue sharing ratio is between 0 and 0.3,the option ordering quantity of farm produce is a decreasing function of the sharing ratio; when the revenue sharing ratio is between 0.3 and 1,the option ordering quantity of farm produce is an increasing function of sharing ratio; when the revenue sharing ratio is between 0.421 and 1,the agricultural producers and retailers' expected profits are an increasing function of sharing ratio.Finally,through the numerical calculation,the applicability of the conclusions is verified,to provide a reference for the supply chain management practices.

CWoT-Share: Context-Based Web of Things Resource Sharing in Blockchain Environment

Web of Things(WoT)resources are not only numerous,but also have a wide range of applications and deployments.The centralized WoT resource sharing mechanism lacks flexibility and scalability,and hence cannot satisfy requirement of distributed resource sharing in large-scale environment.In response to this problem,a trusted and secure mechanism for WoT resources sharing based on context and blockchain(CWoT-Share)was proposed.Firstly,the mechanism can respond quickly to the changes of the application environment by dynamically determining resource access control rules according to the context.Then,the flexible resource charging strategies,which reduced the fees paid by the users who shared more resources and increased the fees paid by users who frequently used resources maliciously,were used to fulfill efficient sharing of WoT resources.Meanwhile,the charging strategies also achieve load balancing by dynamic selection of WoT resources.Finally,the open source blockchain platform Ethereum was used for the simulation and the simulation results show that CWoT-Share can flexibly adapt to the application environment and dynamically adjust strategies of resource access control and resource charging.

基于区块链的联邦蒸馏数据共享模型研究

零散、孤立的海量数据形成“数据孤岛”使得数据无法交互和连接,如何在保护原始数据隐私的前提下安全有效地共享数据中的知识信息已成为热点研究问题。基于以上内容,提出了一种基于区块链的联邦蒸馏数据共享模型(BFDS)。区别于中心化架构,采用区块链联合多参与方组建教师网络,实现分布式协同工作;通过交换蒸馏输出的方式,传递数据中的知识信息,联合训练轻量化模型;提出了一种多权重节点可信评估算法,调用智能合约分配权重并生成可溯源全局软标签,降低因参与方质量差异而产生的负向影响。实验结果表明,BFDS模型能联合多参与方安全可信共享数据知识,协同蒸馏训练模型,降低了模型的部署成本;所提出的多权重节点评估算法能有效减小低质量节点的负向影响,提高了全局软标签的质量与安全性。

非理性偏好下动力电池再制造供应链最优决策与协调研究

考虑动力电池剩余容量不确定特征,构建由电池供应商和汽车制造商组成的再制造供应链,分别探讨决策双方完全理性、单向非理性偏好和双向非理性偏好等5种决策情形下的均衡解。研究发现:动力电池再制造容量起始点对回收量具有正向作用。在双向非理性偏好情形下,供应商的利他(公平)偏好程度增加导致制造商和系统总利润提高(降低),而自身利润总是降低;制造商的非理性偏好对供应链成员及系统利润的影响与供应商的非理性偏好程度有关。在单向非理性情形下,供应链成员的利他(公平)偏好程度增加导致自身利润下降(上升)而对方利润上升(下降)。两部定价契约和收益共享契约能够实现双向非理性偏好情形下再制造供应链的协调。

基于侧链和信任管理模型的数据共享方案

为解决在不信任的区块链环境中由于数据转售而造成的用户不愿共享数据等问题,提出一种基于侧链和信任管理模型的数据共享方案。使用信任管理模型量化节点信任值,将节点信任值集成到数据共享智能合约中,为用户提供可信的共享环境和动态的访问控制接口。对联盟链进行侧链扩容,使用信任管理模型优化共识算法。规定主链使用具有拜占庭容错能力的T-PBFT算法,侧链使用仅适用于高信任场景的T-Raft算法。用户根据预先设置的阈值动态决定在主链或侧链共享数据。实验就方案的安全性和性能进行分析,表明了该方案的可行性和有效性。

交易或合作?双积分政策下汽车制造商积分策略研究

双积分政策实施后,汽车制造企业须调整生产运营策略以应对政策变化为企业带来的影响。以由一个同时生产传统燃油汽车和新能源汽车的汽车制造商和经销商组成的汽车供应链为研究对象,构建汽车制造商的交易策略和合作策略模型,比较不同策略下汽车供应链的分散决策和集中决策;对比分析不同投资金额时汽车制造商的最优积分策略。研究表明汽车制造商可通过直接交易或与其他汽车制造商合作的方式获取新能源正积分;不论汽车制造商选择交易策略或合作策略,汽车供应链集中决策比分散决策更优;当投入的金额较小时,合作策略更有优势;通过收益共享契约协调后,供应链成员收益达到帕累托最优。

数字出版供应链下区块链投资与版权保护策略

区块链技术的可追溯性、安全性以及不可篡改性可以解决数字内容产品的盗版问题。以此为背景,构建由出版商、销售平台以及消费者构成的数字出版供应链,探讨在传统版权保护和区块链下的版权保护两种版权保护模式中的出版商最优定价和平台最优版权保护强度的决策问题,并比较了供应链绩效。研究发现,区块链下的版权保护模式中平台实施严格的版权保护强度,进而提高正版产品的吸引力,需求上升弥补了传统版权保护下出版商通过降价提高需求造成的利润损失。但是,平台只有在区块链投资成本较低时才愿意投资区块链,无法实现供应链的收益最大化。针对这一问题,通过设计契约提高了平台投资区块链的动机。最后,研究了平台投资区块链对购买正版产品消费者的消费者剩余以及社会福利,发现投资区块链可以提高社会福利,但在一定程度上会损害正版产品的消费者剩余。

基于区块链的外包安全多方统计计算可验证隐私保护方案

安全多方求和/乘积是安全多方计算(Secure Multi-Party Computation, MPC)的一种典型问题,近年来在智能电网、电子投票和联合征信等场景中有诸多应用。如何实现数据隐私保护是安全多方求和/乘积计算应用领域的一个关键性问题。针对此问题,引入了区块链构建可信数据共享环境,以此为基础结合可验证秘密共享协议设计了简单可行的基于区块链的外包安全多方统计计算可验证隐私保护方案。应用实例证明了方案的安全性和可行性,理论分析和实验测试表明该方案可实现安全多方统计计算过程中数据的可验证隐私保护,且较Feldman方案在数据验证过程中有更小的计算开销。

新的教育社会契约中的人文主义:传统、局限与超越

随着联合国教科文组织发布《一起重新构想我们的未来:为教育打造新的社会契约》以及联合国召开“教育变革峰会”,新的教育社会契约已成为当今全球教育治理的重要话语。它根植于人文主义传统,与联合国教科文组织此前的前瞻性教育报告一起,建构起与时俱进的人文主义教育思想体系。然而,当人文主义与西方个体理性的底层逻辑相结合时,无法解决个体利益争斗和有效的共同体建设等问题,阻碍了人文主义在全球教育治理中发挥出理想的效果。中华文明中的关系理性能够为新的教育社会契约的未来超越提供思路,培养具备“关系素养”的人来建立真实的“人类命运共同体”,这是中国对未来全球教育治理的可能贡献。

不同数字技术投资模式决策及其对绿色供应链定价影响

将数字技术投资模式引入绿色供应链定价决策中,分别构建数字技术固定投资模式和边际投资模式情形下的供应链模型,研究不同数字技术投资模式对绿色供应链定价决策影响.研究发现,(1)两种模式下,制造商分别存在一个改善自身利润的数字技术投资成本阈值,存在一个数字技术投资合作区间,提出零售商收益分享+罗宾斯坦恩讨价还价模型达成供应链双赢;(2)数字技术边际投资模式下的批发价(零售价)大于数字技术固定投资模式下的批发价格,但数字技术固定投资模式下的产品绿色度比数字技术边际投资模式下大;(3)两种数字技术投资模式都能带来零售商利润的改善,且零售商利润在数字技术固定投资模式下更大.相同数字技术投资总成本下,数字技术固定投资模式更有利于提高供应链成员企业的利润.

基于区块链技术的生鲜农产品溯源系统设计

当前生鲜农产品供应链体系通常采用中心化管理模式,存在不同用户之间信息不对称、缺乏实时信息共享平台以及产品来源可追溯性差等问题。为了解决这些问题,采用区块链技术作为开发框架,提出一个基于区块链技术的生鲜农产品供应链的信息共享和可追溯模型,该模型系统具有信息共享、调度实时控制、溯源机制完善等特点。通过设计智能合约算法和新型的交易提案方式,实现自动化管理生鲜农产品供应链系统,以更好地可视化展现区块链网络交易流程。使用Caliper工具进行性能测试,实验结果表明,该方案可行性高,多节点环境下系统交易时延低,同时可以保证信息安全,具备完善的交易功能。最后,选取几个现有的农产品溯源应用系统做对比分析,该方案相较于现有的农产品溯源应用系统具有更强的溯源监管能力,更高的交易可靠性,以及更好的供应链各环节节点间的数据交互性等优势。

土地经营权入股立法的反思与展望

自家庭联产承包责任制实施以来,关于农村土地承包经营权能否以入股等方式流转,在政策与法律层面经历了比较复杂的变迁过程。土地经营权入股在立法中得到确认是“三权分置”改革的重要成果之一,有利于在流转中更好地实现土地经营权的价值。土地经营权入股现行立法表达不规范、不统一,且与相关法律规定存在冲突,导致立法预期的实现受阻。以立法的基本原理来审视,立法用语不规范只是表面现象,土地经营权的性质不明才是立法困境的根源,对入股所致不利后果的担忧则进一步导致适用难题。实践中大量存在的“以租代转”、“名为入股、实为出租”现象表明,既有立法并不能有效满足土地经营权入股的需求,反而徒增解释与适用的混乱。为了弥合土地经营权入股的认知分歧,保持相关立法之间的协调,实现“三权分置”的立法目的,有必要在立法中统一相关表述,明确规定土地经营权的性质,移除土地经营权承载的不必要负担,让土地经营权真正成为“可以用货币估价并可以依法转让的非货币财产”,进而以“作价出资”取代“入股”。

MaaS旅游供应链收益共享契约设计与协调

针对出行即服务(Mobility as a Service,MaaS)提供定制化的出行服务以满足游客差异化的交通需求,构建了由传统旅游供应商和MaaS平台组成的双渠道旅游出行服务链,探讨不同主导权下的集中式决策和分散式决策策略及其效益,并开展以供应商为主导的供应链收益共享契约设计和数值分析。研究结果发现:基于MaaS的旅游供应链集中式决策下的效益大于分散式决策,且集中式决策效益是以供应商为主导的分散式决策效益的3/4。在收益共享契约协调下,供应商利润和MaaS平台利润分别为0.68和0.58,均有所提高,旅游供应链整体效益最大,实现旅游供应链完美协调。

基于区块链的基因数据安全共享模型

基因数据作为极具私密性的个人数据资产,其隐私保护和价值化已成为当前的研究热门。但目前基因检测行业采取的仍是传统的基因数据共享模式,存在着个人基因数据所有权丢失、基因数据隐私性弱、共享多方协作性差等问题。鉴于此,设计基于区块链的基因数据共享模型,利用区块链技术的去信任化、可追踪溯源等特性,明确个人基因数据的所有权的归属;利用密码学技术和可信硬件,保证基因数据的隐私性;利用智能合约处理共享方间共享流程,建立安全可行的基因数据共享模型,作为基因数据价值流转的技术支撑。最后,简单实现基因数据安全共享操作平台,比较模型的优势并作出安全性分析。

考虑网络口碑的供应链定价与协调研究

随着电子商务和社交网络的迅速发展,网络口碑正在影响和改变消费者的购买习惯,并对企业决策产生重要影响。本文考虑由一个制造商和一个零售商组成的二级供应链,通过建立两阶段定价模型研究网络口碑对供应链定价和协调的影响。首先,文章分析了集中决策下网络口碑对供应链最优定价策略和整体利润的影响;其次,设计批发价契约和收益共享契约对分散决策下的供应链进行协调。研究表明:当受正面口碑影响时,系统会降低第一阶段价格,提高第二阶段价格,且口碑影响力度越大,两阶段的价格差异越小,供应链整体利润越高;当受负面口碑影响时,系统会提高第一阶段价格,降低第二阶段价格,且口碑影响力度越大,两阶段的价格差异越大,供应链整体利润越低;批发价契约无法实现供应链的协调,收益共享契约可以同时改善制造商、零售商和供应链整体利润,实现供应链协调。