1. Sino-British Blockchain Industry Research Institute, Guangxi University, Nanning, Guangxi 530004, P. R. China
2. Tsinghua Shenzhen International Graduate School, Shenzhen, Guangdong 518055, P. R. China
3. The Research Institute of Peking University in Shenzhen, Shenzhen, Guangdong 518057, P. R. China