Added a new configuration option, wpa_ptk_rekey, that can be used to
enforce frequent PTK rekeying, e.g., to mitigate some attacks against TKIP
deficiencies. This can be set either by the Authenticator (to initiate
periodic 4-way handshake to rekey PTK) or by the Supplicant (to request
Authenticator to rekey PTK).
With both wpa_ptk_rekey and wpa_group_rekey (in hostapd) set to 600, TKIP
keys will not be used for more than 10 minutes which may make some attacks
against TKIP more difficult to implement.
We need to cancel the group key update for a STA if a reauthentication
request is received while the STA is in pending group key update. When
canceling the update, we will also need to make sure that the PTK Group Key
state machine ends up in the correct state (IDLE) to allow future updates
in case of WPA2.
IEEE 802.11w/D6.0 defines new AKMPs to indicate SHA256-based algorithms for
key derivation (and AES-CMAC for EAPOL-Key MIC). Add support for using new
AKMPs and clean up AKMP processing with helper functions in defs.h.
This updates management frame protection to use the assocition ping process
from the latest draft (D6.0) to protect against unauthenticated
authenticate or (re)associate frames dropping association.
