Ruby on Rails的SAML 2.0 SSO？

Where can I dig up a Ruby or Ruby on Rails library for SAML 2.0 SSO. I have a set of enterprise applications that are to be built but need to have federated login from a central authentication system. I have used SAML 1.1 and SAML 2.0 in a Microsoft .Net environment but have yet to see a library that handles both SAML Providers and Consumers for Ruby on Rails. Can someone point me in the right direction or tell me if I need to build the library myself?Where can I dig up a Ruby or Ruby on Rails libr