Re: Frequent SM test failure at UPF

[Brian Gix <bgix@codeaurora.org>]

On 2/7/2011 4:26 PM, Brian Gix wrote:
>
> Testing of Shorter than 16 octet keys.
>
> In smp_cmd_pairing_random() when the STK is generated, it needs to be
> truncated to the MIN of conn->preq[4] and conn->pres[4].
>
> This Min value may need to be saved for later as well, because it needs
> to also limit the LTK key exchange.
>
> This failure showed up with the PTS tool, and at least one other device
> during the days testing. I have mocked up a fix, but have not had a
> chance to test it yet.
>
>

PTS also did not like that we request No Bonding, but request to 
exchange keys.  I am not sure who is at fault there. At first glance, 
exchanging keys insinuates a bonded relationship, so I don't know what 
it means to request key exchange but not bond.  I think both sides need 
to agree to bond (bit 0x01 in offset 3 (4th octet) of the req and res) 
to remember the exchanged keys, but exchanging keys should still be OK 
for the duration of that session at least.  They would then be discarded 
when the connection ended.

It also may not make sense to request Bonding, but not have keys to 
exchange, because I am not sure if you are really bonded if you have no 
keys exchanged with the remote device.  You could always just remember 
the remote device's BD Addr, I suppose and choose to accept or reject 
no-security connections based on that.

I am sorry, the above is mostly just me thinking out loud. I don't know 
for sure if any of that is actually correct.


-- 
Brian Gix
bgix@codeaurora.org
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum