1. College of Computer Science and Technology, National Huaqiao University, Xiamen 361021, China
2. Xiamen Key Laboratory of Data Security and Blockchain Technology, National Huaqiao University, Xiamen 361021, China
3. Fujian Key Laboratory of Big Data Intelligence and Security, National Huaqiao University, Xiamen 361021, China
4. Department of Information and Computer Science, Feng Chia University, Taichung 40724, Taiwan