Para openSUSE Leap 15.3 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:ruby:extensions/openSUSE_Leap_15.3/devel:languages:ruby:extensions.repo
zypper refresh
zypper install rubygem-ed25519
Para SLE 15 SP4 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:ruby:extensions/SLE_15_SP4/devel:languages:ruby:extensions.repo
zypper refresh
zypper install rubygem-ed25519
Para SLE 15 SP3 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:ruby:extensions/SLE_15_SP3/devel:languages:ruby:extensions.repo
zypper refresh
zypper install rubygem-ed25519
Para SLE 15 SP2 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:ruby:extensions/SLE_15_SP2/devel:languages:ruby:extensions.repo
zypper refresh
zypper install rubygem-ed25519