Instructions for creating own Nickname and Client Certificate

You can perform the following steps to create your own certificate:

Create .key and .cer files

Replace $username with your nickname in the following OpenSSL Command:
or in Bash: export username=MyNichname

openssl req -nodes -newkey rsa:2048 -keyout /tmp/$username.key -x509 -days 3650 -out /tmp/$username.cer -subj /CN=foo

Create $username.pem

cat /tmp/$username.cer /tmp/$username.key > /tmp/$username.pem

Calculate the Certificate's fingerprint

Run:

openssl x509 -sha256 -noout -fingerprint -in /tmp/$username.pem | sed -e 's/^.*=//;s/://g;y/ABCDEF/ABCDEF/'

Register your nickname

Use your IRC Client like IRSSI to connect to IRCS.
Choose your desired nichname by typing /nick haxor
Register your nick by: /msg NickServ REGISTER yourpasswordhere foo@bar.de

Add your Certificate to your nick

In Irssi run:

/msg NickServ CERT ADD yournicknamehere yourFingerprintHere

Now you can connect to IRCS with your certificate by running in Irssi:

/server -ssl_verify -ssl_capath /etc/ssl/certs -ssl_cert yourcertificate.pem ircs.thc.org