Re: [PATCH 11/21] doc: PKEX support for DPP

[Denis Kenzior <denkenz@gmail.com>]

Hi James,

>>
>> Fair enough, lets explore whether we can provide this via some agent API.
> 
> Reading more about the identifier being used to distinguish a "plurality of 
> devices" this is what I'm thinking as far as the agent interaction:
> 
> It would make sense (on the configurator side) to query an agent _after_ the 
> enrollee sends the PKEX exchange request. That way the configurator can look up 
> the identifier/code, somewhat the same as RequestUserPassword.

Possible.  But isn't the main use case to share the code and initiate on both 
sides independently?

So..
ConfiguratorEnrollee(code, identifier)
StartEnrollee(code, identifier)

> 
> I don't see much benefit of using an agent in StartEnrollee(), and would rather 
> pass via the DBus arguments for simplicity. Adding an agent for this doesn't 
> really gain us anything, it just adds complexity. The caller of the API can 
> still change the code/id for each call it makes to StartEnrollee() as it sees fit.

Okay, sounds fair.

> 
> So something like:
> 
> StartConfigurator()
>      ... waits for PKEX exchange request ...
>      -> RX PKEX exchange request
>          if (id)
>              Agent.RequestUserPassword(id)
>          else
>              Agent.RequestPassphrase()
> 
> (And if we want "SharedCode" Agent APIs, that's fine, these just fit the need)
> 
> The one caveat here is the timing since the PKEX exchange response must come 
> within 200ms, which isn't possible for a human user. A human configurator would 
> need to establish the code/id completely ahead of time.
Well, that's why it says to retransmit 5 times.  But even then, that isn't 
enough time for a human to process this.  Hence my point above, that the 
use-case seems geared towards both sides entering the shared code without any 
'trigger' from the peer.

What you propose here is using the Agent, but only for as a way to machine 
generated a response.  Sounds like maybe:

StartConfigurator(object shared_code_agent_path)?

Regards,
-Denis