A decentralized crypto network with dynamic threshold change

The threshold proxy re-encryption (tPRE) algorithm not only ensures the separation of data ownership and use right, but also prevents a single data proxy from doing evil. In order to avoid collusion of multiple data proxies, this paper constructs a decentralized crypto network (DCN) based on blockchain technology and tPRE. DCN is more than a key management system, while expanding the data storage capacity of blockchain network. Combined with existing distributed storage schemes, it can store massive data. Due to Byzantine failure in distributed networks, the data proxy nodes can join or leave at will. In order to ensure that the number of data proxy nodes in the DCN network meets the requirements of the re-encryption threshold, and the data authorization operation can be carried out smoothly, this paper presents a dynamic refresh method of tPRE fragments. When there are fragments that meet the threshold number in the network, the allocation of encrypted fragments can be adjusted non-interactivity and self-adaptively. Non-interactivity means that each data proxy node independently refreshes its old fragments into new fragments without collecting old fragments from other nodes in the DCN, and then distributes the new fragments to other data proxy nodes in the DCN. Self-adaptability refers to monitoring the changes of data proxy node sets in the DCN, and automatically refreshing fragments. Finally, the performance of critical algorithms is calculated in the proposal.