1. University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
2. UCL Centre for Blockchain Technologies, Malet Place, London WC1E 6BT, UK
3. Branch Business & Information Systems Engineering of the Fraunhofer, FIT and FIM Research Center, Wittelsbacherring 10, 95444 Bayreuth, Germany