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From:   Sonny Sasaka <sonnysasaka@chromium.org>
Date:   Tue, 15 Feb 2022 08:49:55 -0800
Message-ID: <CAO271mkRwR9nMe79d78wJSiyybHjiZdGtGApAWBJjWqPYT3KYA@mail.gmail.com>
Subject: Re: Question about Trusted property
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc:     BlueZ <linux-bluetooth@vger.kernel.org>
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Hi Luiz,

Friendly ping here. Could you respond to my RFC about adding "Bonded"
property? I am about to write the patch but I would like to hear
whether this makes sense from your perspective. Thanks.

On Thu, Feb 10, 2022 at 4:02 PM Sonny Sasaka <sonnysasaka@chromium.org> wrote:
>
> Hi Luiz,
>
> Thanks for the clarification. So my guess was right that it does not
> have to do with bondedness. In that case, do you think it makes sense
> to add a "Bonded" flag property to org.bluez.Device1? There are some
> use case flows that pair with a peer device but do not actually bond,
> and just with Paired property the UI can't know whether to show this
> device as "Bonded" or not.
>
> On Thu, Feb 10, 2022 at 1:30 PM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> >
> > Hi Sonny,
> >
> > On Thu, Feb 10, 2022 at 11:23 AM Sonny Sasaka <sonnysasaka@chromium.org> wrote:
> > >
> > > Dear maintainers,
> > >
> > > Friendly ping on this question. Does adding "Bonded" property to
> > > org.bluez.Device1 make sense?
> > >
> > > On Fri, Feb 4, 2022 at 4:02 PM Sonny Sasaka <sonnysasaka@chromium.org> wrote:
> > > >
> > > > Hi Luiz/BlueZ maintainers,
> > > >
> > > > What is the purpose of the Trusted property on org.bluez.Device1
> > > > interface? Does it mean whether the device is bonded? My experiment
> > > > with BlueZ shows that sometimes a device with "Trusted" property set
> > > > is not bonded (does not have pairing key stored) and also vice versa,
> > > > so I am assuming that the Trusted property means something else. What
> > > > is an example use case of the Trusted property?
> > > >
> > > > Eventually, what I am trying to achieve is for BlueZ clients to find
> > > > out whether a device is Bonded or not. Using the Paired property is
> > > > not very accurate because it is set to true during connection although
> > > > the device is not bonded (pairing key does not persist after
> > > > disconnection). For this purpose, I am about to propose adding
> > > > "Bonded" property to org.bluez.Device1. Some use cases include when
> > > > there is a temporary pairing with a peer device we don't want UI to
> > > > show that the device is in the Bonded device list. What do you think
> > > > about exposing the Bonded state via D-Bus? I will do the
> > > > implementation if this idea makes sense.
> > > >
> > > > Thanks!
> >
> > Trusted primary use is to bypass agent authorization, so when set the
> > agent will not have to authorize profile connections, and yes you can
> > set a device to be Trusted even without having it paired since the
> > bonding procedure refers to authentication rather than authorization
> > which is what Trusted controls.
> >
> >
> > --
> > Luiz Augusto von Dentz