CoSIS: A Secure, Scalability, Decentralized Blockchain via Complexity Theory

Abstract

As the origin of blockchains, the Nakamoto Consensus protocol is the primary protocol for many public blockchains (e.g., Bitcoin) used in cryptocurrencies. Blockchains need to be decentralized as a core feature, yet it is difficult to strike a balance between scalability and security. Many approaches to improving blockchain scalability often result in diminished security or compromise the decentralized nature of the system. Inspired by network science, especially the epidemic model, we try to solve this problem by mapping the propagation of transactions and blocks as two interacting epidemics, called the CoSIS model. We extend the transaction propagation process to increase the efficiency of block propagation, which reduces the number of unknown transactions. The reduction of the block propagation latency ultimately increases the blockchain throughput. The theory of complex networks is employed to offer an optimal boundary condition. Finally, the node scores are stored in the chain, so that it also provides a new incentive approach. Our experiments show that CoSIS accelerates blocks’ propagation and TPS is raised by 20% $\sim ~33$ % on average. At the same time, the system security can be significantly improved, as an orphaned block rate is close to zero in better cases. CoSIS enhances the scalability and security of the blockchain while ensuring that all changes do not compromise the decentralized nature of the blockchain.