For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:brassh:branches:security/openSUSE_Tumbleweed/home:brassh:branches:security.repo
zypper refresh
zypper install libnitrokey
For openSUSE Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:brassh:branches:security/openSUSE_Factory/home:brassh:branches:security.repo
zypper refresh
zypper install libnitrokey
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:brassh:branches:security/16.0/home:brassh:branches:security.repo
zypper refresh
zypper install libnitrokey
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:brassh:branches:security/15.6/home:brassh:branches:security.repo
zypper refresh
zypper install libnitrokey