This is a SimpleSAMLphp module to leverage YubiKey devices to authenticate users in different ways. For the moment, it provides an authentication processing filter that allows you to require a user to use a YubiKey to complete authentication, effectively implementing two-factor authentication. This filter can be combined with any other authentication source, provided that the identifier (or identifiers) of the key registered for that user is available as an attribute.
Migrated to GitLab: https://gitlab.com/code-enigma/simplesamlphp-module-yubikey