On archlinux, to automatically connect your wifi on boot to a hidden, wpa2 encrypted network, create a wpa_supplicant.conf that looks similar to this:

ctrl_interface=DIR=/var/run/wpa_supplicant
network={
ssid=”my wifi essid”
psk=randomnumberlettercombinationhere
}

The ctrl_interface is required to store session data.

Then you also need a netcfg profile. Copy the file from /etc/network.d/examples/wireless-wpa-config to/etc/network.d/myname and edit the file to look similar to this:

CONNECTION=’wireless’
DESCRIPTION=’A wpa_supplicant configuration based wireless connection’
INTERFACE=’wlan0′
SECURITY=’wpa-config’
WPA_CONF=’/etc/wpa_supplicant.conf’
IP=’dhcp’
PRE_UP=’ifconfig wlan0 up | iwconfig wlan0 essid myessidhere’

Edit the WPA_CONF to point at the previously created wpa_supplicant.conf.

Now edit your /etc/rc.conf network and daemons configuration:

NETWORKS=(myname)
DAEMONS=(syslog-ng dbus hal @network @net-profiles @openntpd netfs crond sshd alsa slim)

On your next boot, the wifi should automatically try to connect and establish a connection. You can also try netcfg2 myname to debug it.