Can this plugin allow sub blog owner to selecitvely make the sub blog visible to her/his friends?

How can sub blog owner/admin password-protect the whole sub site? Just like change the visibility of a post to password protected, but on the whole sub blog/site level. And this protection is set by each sub blog owner on a site by site basis.

Can "Multisite privacy" do that or any other plugin/solution can achieve that?

Thanks and Happy New Year!