1. Introduction
The use of finger-vein as a type of a biometric characteristic for verification is growing in recent years, especially for banking transaction applications, where there is a need for highly secure access control [9]. The practical example of such systems can be found in commercial applications that were developed by Hitachi in 2004 with finger-vein verification mainly for use in unsupervised scenarios such as Bank ATMs [9]. Despite the high recognition accuracy of such finger-vein systems, they are prone to attacks at the capture level where one can use an artefact (e.g., printed finger-vein image) to gain illegitimate access, especially in unsupervised access control settings. Such attacks at the capture level are popularly termed as presentation attacks (aka., spoofing attacks), and attacks can be carried out using different kind of artefacts, such as using a printed photo of a finger-vein representation (print-attack) or alternatively using an electronic display to show the vein representation (display-attack)[24].