Re: [Open1x-xsupplicant] [Linux] Problem with 2/4 of 4-way handshake

[Klaus M. <kmu...@ju...>]

Hello!

Meanwhile, I think I know why the MIC is considered invalid on the AP. I
detected, that the PTK derivation done by xsupplicant doesn't match the
request of 802.11i as defined in Part 11 / Amendment 6 on page 90 and
following:

When using ccmp as pairwise key cipher, the ptk has a size of 384 bits
(and not 512 as implemented - I couldn't find any differentiation at
this point between 384 (ccmp) or 512 bits (tkip)).

But even if the size is set correctly, the PTK derived in xsupplicant is
another as in hostapd (but now with the same length). The PMK is the
same on both sides.

Another incompatibility seems to me, that the key length field on frame
2/4 sent by xsupplicant is set to a value > 0 (the value is taken from
frame 1/4). According the 802.11i standard, this should be 0 (see page 102).



Kind regards,
Klaus