Tiki as a SAML IDP
You probably want Tiki as a Service Provider (SP). Please see SAML.
If you require Tiki to be an Identity provider (IdP): It has been done but it's not properly documented. The general idea is to install SimpleSAMLphp and let SimpleSAMLphp access Tiki's database. Please see: https://github.com/pitbulk/tiki-saml/blob/master/doc/tiki_wiki_as_idp.rst
If you need this feature and would like this to be streamlined, documented and future-proof (as was done for Tiki as a Service Provider ), please contact Marc Laporte (en/fr/sp) or Torsten Fabricius (de/en) so we can make this happen together.