demantz

* Download root_ca and intermediate_ca certificates from https://www.hackint.org/ca
* Verify the fingerprint of the root certificate!
* Store the certificates in your local certificate directory (e.g. /usr/share/ca-certificates/)
* Symlink both certificates to /etc/ssl/certs/
* NOTE: I had to rename the certs to *.pem in order for irssi to read them
* Change your .irssi/config:
...
 {
    address = "irc.hackint.org";
    chatnet = "hackint";