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From:   Szymon Janc <szymon.janc@codecoup.pl>
To:     Ordit Gross <ordit.gross@orcam.com>
Cc:     linux-bluetooth@vger.kernel.org
Subject: Re: recommended way to register on bluetooth event
Date:   Wed, 02 Oct 2019 13:24:16 +0200
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Hi,

On Tuesday, 1 October 2019 15:36:19 CEST Ordit Gross wrote:
> hi all,
> I would like to register on encryption changed event.
> As far as I could tell mgmt-api does not consist of such capability.
> I think that reading from an HCI socket may enable me to read all
> events (and the needed one as well).
> is there a better way of registering on encryption changed event?
> 
> The reason I need this capability in the first place is that I want to
> enable repairing if BLE Peripheral Removes Pairing keys.
> currently, when the peripheral deletes his side of keys and attempt to
> connect to master, the master will get  encryption changed event with
> error  "PIN or Key Missing".
> that's why I want to be notified on application that we got this
> event, so I can delete my side of keys as well..
> 
> any suggestions?
> thanks in advance!!
> Ordit

Ha, I was working on that few years back but unfortunatelly it never got in... 
mostly due to objections about dropping old keys before new pairing (which I 
don't think is necessary with proposed Agent consent-based approach but others 
were not sharing my view on this ;-).

Kernel part with reporting proper error to userspace is done so userspace has 
all the information it needs. For bluetoothd I've sent RFC [1] which might 
give you a bit of headstart while working on this. In short, it extends Agent 
API with new call used to consent re-bond of remote device.

[1] https://marc.info/?l=linux-bluetooth&m=147031736607899&w=2

-- 
pozdrawiam
Szymon Janc