Facebook’s offical .onion domain
that they have an offical
.onion domain: https://facebookcorewwwi.onion/
What’s interesting is that their
.onion is serving SSL and the SSL certificate’s SNAs
.onion so that Tor Browser doesn’t complain about an invalid cert.
There was a discussion about just that on the CA/Browser Forum two weeks earlier, started by an DigiCert employee. Unsuprisingly Facebook’s certificate is issued by DigiCert.