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