Information-theoretic secure rational secret sharing in asynchronous networks for untrusted cloud environments

Today, cloud storage services increased the popular for data storage in the cloud and retrieve from any location without any time limitations. One of the most important demands required in cloud is secured data transmission in un-trusted cloud applications. Particularly, secure and efficient multiparty communications in Untrusted Cloud Environments (UCE) attract widespread attentions. The equipment used in UCE have the particularity of being heterogeneous and UCE communication environment are asynchronous networks in which multiple users cannot transmit their messages simultaneously. How to ensure secure communication between these heterogeneous intelligent devices is a major challenge for multiparty communication applied in UCE. In such an asynchronous environment, the asynchronous transmission can cause security problems in cryptographic functions. Therefore, how to implement rational secret sharing (RSS) in an asynchronous model of the UCE networks has become a burning research topic. The RSS refers to finding a solution composed of strategies to encourage players in the secret reconstruction to act honestly even players are rational to act for their own interest. If each player plays the game for the best response to the best response of other players, the game is in Nash equilibrium. The objective of an RSS is to achieve the Nash equilibrium state corresponding to the global optima. In this paper, we propose an information-theoretic secure RSS in asynchronous model for UCE. Our design uses Petersen's VSS to allow every player to divide his share into multiple pieces for other players. Then, shares can be revealed asynchronously. If any player acts maliciously, his share can be recovered by other players. This feature can encourage players to act honestly since any malicious action (i.e., either revealing a fake share or refusing to release one) is useless. Our scheme is practically valuable for secure group-oriented applications in UCE.