组密钥协商协议用于解决多个参与方在不安全的通信网络中的组消息传递安全问题。然而现有方案存在通信效率低、计算开销大、群组规模难以扩大、安全性不足等问题。针对组密钥协商中的这些问题,设计了一种可聚合共享棘轮树算法,并基于此...组密钥协商协议用于解决多个参与方在不安全的通信网络中的组消息传递安全问题。然而现有方案存在通信效率低、计算开销大、群组规模难以扩大、安全性不足等问题。针对组密钥协商中的这些问题,设计了一种可聚合共享棘轮树算法,并基于此提出了一个基于可聚合广播的安全可追溯组密钥协商协议(Traceable Group Key Agreement,TGKA)。TGKA协议将基于签名的可聚合广播方案与密钥封装的思想结合,通过棘轮树将用户划分为多个子组,在子组之间进行密钥协商,从而减小其在计算与通信上的开销,实现了动态组的高效密钥更新。实验结果表明,在确保了组密钥协商协议安全性的同时,TGKA协议能够降低群组发送者与接收者的通信复杂度,在数十至数百用户的中型组中具备一定的可行性。展开更多
This paper studies the backward-forward linear-quadratic-Gaussian(LQG)games with major and minor agents(players).The state of major agent follows a linear backward stochastic differential equation(BSDE)and the states ...This paper studies the backward-forward linear-quadratic-Gaussian(LQG)games with major and minor agents(players).The state of major agent follows a linear backward stochastic differential equation(BSDE)and the states of minor agents are governed by linear forward stochastic differential equations(SDEs).The major agent is dominating as its state enters those of minor agents.On the other hand,all minor agents are individually negligible but their state-average affects the cost functional of major agent.The mean-field game in such backward-major and forward-minor setup is formulated to analyze the decentralized strategies.We first derive the consistency condition via an auxiliary mean-field SDEs and a 3×2 mixed backward-forward stochastic differential equation(BFSDE)system.Next,we discuss the wellposedness of such BFSDE system by virtue of the monotonicity method.Consequently,we obtain the decentralized strategies for major and minor agents which are proved to satisfy the-Nash equilibrium property.展开更多
为揭示全球价值链(global value chain,GVC)双向嵌入对研发投入的影响,利用附加值分解方法识别GVC双向嵌入度,基于72个国家和地区行业层面面板数据进行实证研究。研究发现:GVC前向嵌入通过增强竞争和行业获利能力促进研发投入强度提升,...为揭示全球价值链(global value chain,GVC)双向嵌入对研发投入的影响,利用附加值分解方法识别GVC双向嵌入度,基于72个国家和地区行业层面面板数据进行实证研究。研究发现:GVC前向嵌入通过增强竞争和行业获利能力促进研发投入强度提升,而GVC后向嵌入通过增强国外研发溢出的替代作用及限制行业获利降低研发投入强度;数字技术不仅可放大GVC前向嵌入对研发投入强度的提升作用,还可缓解GVC后向嵌入对研发投入强度的降低作用。另外,GVC前向嵌入的研发投入强度提升作用对于发达国家更强,而后向嵌入的研发投入强度抑制作用对于发展中国家更大,且这两项作用在资本和技术密集型行业尤为突出。展开更多
文摘组密钥协商协议用于解决多个参与方在不安全的通信网络中的组消息传递安全问题。然而现有方案存在通信效率低、计算开销大、群组规模难以扩大、安全性不足等问题。针对组密钥协商中的这些问题,设计了一种可聚合共享棘轮树算法,并基于此提出了一个基于可聚合广播的安全可追溯组密钥协商协议(Traceable Group Key Agreement,TGKA)。TGKA协议将基于签名的可聚合广播方案与密钥封装的思想结合,通过棘轮树将用户划分为多个子组,在子组之间进行密钥协商,从而减小其在计算与通信上的开销,实现了动态组的高效密钥更新。实验结果表明,在确保了组密钥协商协议安全性的同时,TGKA协议能够降低群组发送者与接收者的通信复杂度,在数十至数百用户的中型组中具备一定的可行性。
基金support partly by RGC Grant 502412,15300514,G-YL04.ZWu acknowledges the Natural Science Foundation of China(61573217),111 project(B12023)the National High-level personnel of special support program and the Chang Jiang Scholar Program of Chinese Education Ministry.
文摘This paper studies the backward-forward linear-quadratic-Gaussian(LQG)games with major and minor agents(players).The state of major agent follows a linear backward stochastic differential equation(BSDE)and the states of minor agents are governed by linear forward stochastic differential equations(SDEs).The major agent is dominating as its state enters those of minor agents.On the other hand,all minor agents are individually negligible but their state-average affects the cost functional of major agent.The mean-field game in such backward-major and forward-minor setup is formulated to analyze the decentralized strategies.We first derive the consistency condition via an auxiliary mean-field SDEs and a 3×2 mixed backward-forward stochastic differential equation(BFSDE)system.Next,we discuss the wellposedness of such BFSDE system by virtue of the monotonicity method.Consequently,we obtain the decentralized strategies for major and minor agents which are proved to satisfy the-Nash equilibrium property.
文摘为揭示全球价值链(global value chain,GVC)双向嵌入对研发投入的影响,利用附加值分解方法识别GVC双向嵌入度,基于72个国家和地区行业层面面板数据进行实证研究。研究发现:GVC前向嵌入通过增强竞争和行业获利能力促进研发投入强度提升,而GVC后向嵌入通过增强国外研发溢出的替代作用及限制行业获利降低研发投入强度;数字技术不仅可放大GVC前向嵌入对研发投入强度的提升作用,还可缓解GVC后向嵌入对研发投入强度的降低作用。另外,GVC前向嵌入的研发投入强度提升作用对于发达国家更强,而后向嵌入的研发投入强度抑制作用对于发展中国家更大,且这两项作用在资本和技术密集型行业尤为突出。
