English is not my native language so please be patient.
When I don't know how to configure something, sometimes I let the system do it for me, mostly of the times, things works with default values. In this case, if you don't know the function of the
group parameters. You could check this Page or read below:
pairwise: list of accepted pairwise (unicast) ciphers for WPA CCMP =
AES in Counter mode with CBC-MAC [RFC 3610, IEEE 802.11i/D7.0] TKIP =
Temporal Key Integrity Protocol [IEEE 802.11i/D7.0] NONE = Use only
Group Keys (deprecated, should not be included if APs support pairwise
keys) If not set, this defaults to: CCMP TKIP
group: list of accepted group (broadcast/multicast) ciphers for WPA
CCMP = AES in Counter mode with CBC-MAC [RFC 3610, IEEE 802.11i/D7.0]
TKIP = Temporal Key Integrity Protocol [IEEE 802.11i/D7.0] WEP104 =
WEP (Wired Equivalent Privacy) with 104-bit key WEP40 = WEP (Wired
Equivalent Privacy) with 40-bit key [IEEE 802.11] If not set, this
defaults to: CCMP TKIP WEP104 WEP40
This setup works for me, change it according to your ssid and password (psk)
iface wlan0 inet dhcp
# ap_scan can be 0, 1, or 2. Some sources say use 2 but 1 work for me.
# This is needed for hidden SSIDs
# RSN for WPA2 or WPA for WPA1
# WPA-PSK or WPA-EAP
# CCMP for AES or TKIP for TKIP.
# OPEN for WPA1/2 or SHARED or LEAP
About the line
scan_ssid=1 will be some controversy because some more experimented users don't like the hidden ssid thing, but this works for me.
Hopefully this works for you also.