Nucleus SSO with Shibboleth

Hi,
We are having trouble getting shibboleth single sign-on SSO setup with nucleus. In particular we need to know:

The info that I would need is whether the app is looking for a signed assertion and the certificate the the SP is trying to use to sign it. That would be on the nucleus end.

We have been unable to find this information.

@dlindsey can you help with this? Thanks !