**6. Conclusions, Limitations, and Future Work**

This paper proposes the use of a multi-biometric system, which is useful for identification and verification of a person through his/her hand geometry and bloodstream behavior (at the upper part of the hand). The study experimentally tested the effectiveness of the system using a number of research participants. The system proved to be able to verify users with high precision by demonstrating good differentiating abilities. The ERR value of the system is estimated as 5%, which is higher than most existing systems (Table 1). This can, however, be optimized. The proposed system is flawed on the lengthy time taken to carry out the verification. As such, attaining commercial usage would mean optimizing an extraction algorithm for the biometric characteristics. This aspect paves way for future research, with goals of speeding up user identification and verification time.

**Author Contributions:** Conceptualization, L.K., O.K., A.S. and K.K.; methodology, L.K., O.K., O.F. and A.S.; software, L.K. and O.K.; validation, A.S. and O.K.; formal analysis, L.K. and O.K.; investigation, L.K.; resources, O.K., K.K. and A.S.; data curation, L.K., A.S. and O.K.; writing—original draft preparation, L.K. and O.K.; writing—review and editing, O.F. and O.K.; visualization, O.F. and O.K.; supervision, A.S., K.K. and O.K.; project administration, O.K. and K.K.; funding acquisition, O.K. and K.K.

**Funding:** The work and the contribution were mainly supported by project of excellence 2019/2205, Faculty of Informatics and Management, University of Hradec Kralove. The work was also partially funded by the: (1) the Ministry of Education, Youth and Sports of Czech Republic (project ERDF no. CZ.02.1.01/0.0/0.0/18\_069/0010054), (2) Universiti Teknologi Malaysia (UTM) under Research University Grant Vot-20H04, Malaysia Research University Network (MRUN) Vot 4L876 and (3) the Fundamental Research Grant Scheme (FRGS) Vot 5F073 supported under Ministry of Education Malaysia for the completion of the research.

**Acknowledgments:** We are grateful for the support of student Sebastien Mambou and Michal Dobrovolny in consultations regarding application aspects. The APC was funded by project of excellence 2019/2205, Faculty of Informatics and Management, University of Hradec Kralove.

**Conflicts of Interest:** The authors declare no conflict of interest.
