Hello!
I have created another variant for XWiki authenticator, using SAML
Security Token Service (STS) authentication. It is pushed in Github fork
https://github.com/ValdisVitolins/sandbox/tree/master/authenticators/xwiki-…
and I'd be happy if you will include it (doing some cleanup, if
necessary) in XWiki Sandbox repository.
Note, that although this module uses SAML as an high level standard,
actually it is quite different from
https://github.com/xwiki-contrib/sandbox/tree/master/authenticators/xwiki-a…
because it uses quite old SAML 1.2 standard:
http://docs.oasis-open.org/wsfed/federation/v1.2/os/ws-federation-1.2-spec-…
and Authentication provider is implemented using Microsoft technologies.
Valdis