WPS: dev_pw_id mismatch

Jouni Malinen j at w1.fi
Mon May 27 17:46:38 EDT 2013

On Mon, May 27, 2013 at 07:41:07PM +0000, Syed Asifful Dayyan Rafiuddeen wrote:
> WFD Cert test cases which use WPS keypad config method to connect with Auto GO are failing due to mismatch of device password id between M1 and M2. CLUT sends M1 with device password id 5, in response to this test bed Auto-GO sends device password id 0 in M2, due to this mismatch CLUT(wpa_supplicant) sends a NAK msg and WPS is failing.

I don't think wpa_supplicant would behave in this way as a GO since it
does not normally use the P2P special case of Device Password ID when a
P2P Client is joining an already operating group, but that is indeed a
possible exchange with P2P.

> This issue seems to exist even before, but it is failing now because of device password id check that has been recently added for NFC handover in wpa_supplicant (wps_process_dev_pw_id).

It looks like the P2P design on how Device Password ID is used is not
exactly compliant with the WSC specification expectations on Device
Password ID use in M1/M2. Commit
b4a17a6ea74b2ffba082e05c84730e979513042c added support for the WSC style
case where the Registrar is allowed to change the Device Password (e.g.,
from PBC or NFC password token to PIN). However, this did not take into
account this special case with P2P Registrar-specifies and Default PIN.

> What do you think, who should be fixed for this, Registrar or Enrollee? 

I don't think there is much of a choice here apart from relaxing that
validation step in Enrollee.


Jouni Malinen                                            PGP id EFC895FA

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