WIDCOMM BT link keys - where are they?

Archived from groups: alt.cellular.bluetooth (More info?)

Hello!

I have a dual boot system - Linux plus Windows. I bought X-Micro BT USB
dongle and it works like a charm. Both in Windows and Linux.

Here comes the problem - link key for paired devices is kept in the OS. So,
if I pair the phone under Windows I lose pairing in the Linux and
vice-versa. My idea is to grab the key from Windows and inject it into
Linux.

Moreover - I use the same dongle in a few computers, each time I need to
re-pair device due to key mismatch. Copying of the key should solve the
problem.

Is it possible?

Best regards,

--
Pawel Kraszewski

Archived from groups: alt.cellular.bluetooth (More info?)

On Tue, 31 Aug 2004 12:23:51 +0200, Pawe³ Kraszewski
<Pawel_Kraszewski@wp.pl> wrote:

>Hello!
>
> I have a dual boot system - Linux plus Windows. I bought X-Micro BT USB
>dongle and it works like a charm. Both in Windows and Linux.
>
> Here comes the problem - link key for paired devices is kept in the OS. So,
>if I pair the phone under Windows I lose pairing in the Linux and
>vice-versa. My idea is to grab the key from Windows and inject it into
>Linux.
>
> Moreover - I use the same dongle in a few computers, each time I need to
>re-pair device due to key mismatch. Copying of the key should solve the
>problem.
>
> Is it possible?
>
> Best regards,

I have a similar problem in that I use the same BlueTooth dongle on
two computers.

As long as your BT software on all OS/Systems has the same BT name and
you use the same pairing passkey then it should work fine without the
need to re-pair.

Pairing is based on the MAC address of the device, in this case the
dongle's MAC address to the phone's MAC address.

As far as the phone is concerned it is connecting to the Dongle not
the computer so as long as bt name and passkey are the same, it should
work... Does for me!

--


Shevek

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Archived from groups: alt.cellular.bluetooth (More info?)

Henryk Plötz wrote:

[cut]

Thank you for competent answer!

Well, I understand BT cryptography as this (key names are my own, they
correspond to the ones specified by Henry):

1. Two devices are unpaired, never seen each other before
2. Before "pairing", during "discovery" they learn each other's MAC (or
whatever the unique ID is called in BT)
3. During "pairing" they use PIN, MAC and some random data to generate
"pairing key", confirming, that device is paired to the other. This key is
stored on the both devices. On computer-side I guess it is stored on the
harddisk rather than in the BT USB dongle. It is at least for Linux BlueZ
driver.
4. "pairing key" is used to generate "session key" for each subsequent
connection.

Paired device recognizes its counterpart by MAC and "pairing key". Mismatch
on MAC and key requires re-pairing.

So, if I pair my mobile with my computer at home via BT dongle and than take
mobile _and_ dongle to my work, the mobile doesn't see the change (MAC of
the dongle hasn't changed), but "pairing key" on work PC doesn't match one
expected by mobile. After I re-pair, everything is OK until I get home.

But - if I move "pairing key" _with_ the dongle, the mobile won't notice,
that the computer it is connecting to has changed. Therefore I won't need
to re-pair mobile at work. It will still think it's at home

So - where might I find that "pairing key" (this probably be the "unit key"
in Henry's note) in WIDCOMM software???? This would be something like
cloning of the BT device identity...

Best regards,

--
Pawel Kraszewski

Hi!

The given information for WIDCOMM BT driver is in the registry:


HKEY_CURRENT_USER\Software\Widcomm\BTConfig\LinkKeys



Have a nice life

JC