WPA Supplicant

My /etc/wpa_supplicant/wpa_supplicant.conf:

#####

ctrl_interface_group=0

ap_scan=2

network={
ssid="My_SSID"
proto=WPA2
key_mgmt=WPA-PSK
pairwise=CCMP
group=CCMP
psk=This_is_a_64-character_PSK_generated_using_wpa-passphrase
}

#####

What I found out only after a very long time:

For example, if:
SSID = home
passphrase (the password you enter in your modem / router) = mypassword

The psk to be entered in wpa_supplicant.conf is generated using: 

wpa_passphrase home mypassword

I.e: Do not enter your original password in the psk column, instead, use the psk generated using wpa_passphrase

If you want to enter your original password in the psk column, the password must be in quotation marks:

psk="mypassword"