Secure communication across the Internet requires cryptography.
This page documents the keys I use.
For email I use PGP/GPG - I have never seen the point of S/MIME.
For remote logon I use ssh (I refuse to use telnet/rlogin).
Before using these keys be sure to verify them by some other means than this page (call me, email me or check the signatures on my pgp key and if you find someone you know, then use gpg/pgp to verify the signatures of my ssh keys).