1. Centre for Digital Forensics and Cyber Security, Tallinn University of Technology, Tallinn, Estonia
2. Information Systems Group, Tallinn University of Technology, Tallinn, Estonia
3. Guardtime, Lausanne, Switzerland
4. Mitsubishi UFJ Research and Consulting, Minato, Tokyo, Japan
5. Guardtime, Tallinn, Estonia
6. School of Computing and Digital Technology, Birmingham City University, Birmingham, U.K.
7. Applied Artificial Intelligence Group, Tallinn University of Technology, Tallinn, Estonia