标准信道下的抗敌手的理性秘密共享方案  

Rational Secret Sharing Scheme Resisting Against Malicious Adversaries in Standard Communication Networks

作　　者：祁冠杰 周展飞[1,2] 

机构地区：[1]中国科学院信息工程研究所信息安全国家重点实验室,北京100093 [2]中国科学院数据与通信保护研究教育中心,北京100093 [3]中国科学院大学,北京100049

出　　处：《密码学报》2016年第4期408-418,共11页Journal of Cryptologic Research

摘　　要：有关理性秘密共享的研究指出,若参与者是想要最大化个人利益的理性参与者,则将无动机在协议中共享份额,从而导致秘密共享的失败.本文研究内容是,在秘密共享中,n个参与者是理性参与者或者是行为任意的恶意参与者.先前考虑恶意参与者的理性秘密共享的相关研究都需要广播信道,这在现实中是很难实现的.本文给出的理性秘密共享方案首次做到了能够在标准信道下抵抗恶意敌手.方案通过多轮交互,真实轮未知的机制,导致偏离的收益不会比遵循协议的收益高,从而使得理性参与者不会选择偏离协议.在协议进行中,方案使用可验证的随机函数来检测恶意参与者的偏离,同时使用基于拜占庭一致的广播协议来对此偏离达成一致并在后续协议中屏蔽该参与者,从而避免了恶意参与者的持续伤害.同时给出了一种新的均衡概念,即计算意义下关于敌手结构的序贯均衡,并给出了相关证明.在此均衡概念衡量下,恶意敌手不能阻止理性参与者重组秘密,而且对于恶意敌手的任意行为,理性参与者没有动机去偏离协议,保证了协议的顺利进行.The research of rational secret sharing reveals that if players are selfish to maximize their benefits, they would not have incentives to send their shares which will lead to the failure of secret sharing process. This paper studies secret sharing in the model where none of the players are honest: they are either rational or malicious, acting arbitrarily. Previous works considering adversaries in rational secret sharing need broadcast channels, which may not be available in reality. This paper proposes a rational secret sharing scheme which can resist against malicious adversaries in standard communication networks. The protocol consists of several rounds and players do not know in advance which round is the true round. Using this mechanism, rational players cannot increase their payoff by deviation, thus rational players have no incentive to deviate from the protocol. Furthermore, we use verifiable random function to detect the deviation of malicious adversaries, and apply the broadcast protocol based on Byzantine agreement to reach an agreement on the deviation to disqualify malicious players, hence to prevent the malicious players' further damage. A new equilibrium concept is also proposed which is called computational sequential equilibrium with respect to adversary structure, and related proof is given. Based on this equilibrium, malicious adversary cannot disturb rational players to reconstruct the secret and rational players have no incentive to deviate no matter how adversaries behave.

关 键 词：理性秘密共享 标准信道 序贯均衡 恶意敌手 广播协议 

分 类 号：TN918.1[电子电信—通信与信息系统]