Different public for every site (which is what google proposed: http://www.computer.org/cms/Computer.org/ComputingNow/pdfs/AuthenticationAtScale.pdf http://www.

Different public for every site (which is what google proposed: http://www.computer.org/cms/Computer.org/ComputingNow/pdfs/AuthenticationAtScale.pdf http://www.computer.org/cms/Computer.org/ComputingNow/pdfs/A...)