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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
6 answers Last reply
More about widcomm link keys they
  1. 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

    Get DigiGuide - a downloadable desktop PC TV and Radio Guide
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  2. Archived from groups: alt.cellular.bluetooth (More info?)

    "Shevek" <shevekFOADSPAMMERS@FOADSPAMMERSmoldy.me.uk> wrote in message
    news:hv79j097a75s2rdm1gjj3bbgcqp4k9h5pu@4ax.com...
    > 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!
    >

    Interesting. It doesn't work for a lot of people and was understood that
    pairing information had key + MAC + other random information.


    --
    Mauricio Freitas, Microsoft MVP Mobile Devices
    Bluetooth guides: http://www.geekzone.co.nz/content.asp?contentid=449
    Performance Centre (Pocket PC reviews):
    http://www.geekzone.co.nz/content.asp?ContentId=2028
    Handango discount: http://www.geekzone.co.nz/handango_code.asp
  3. 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
  4. Archived from groups: alt.cellular.bluetooth (More info?)

    In <news:ch5emi$epc$1@nemesis.news.tpi.pl> Pawe³ Kraszewski wrote:
    > [...] So - where might I find that "pairing key" (this probably be the
    > "unit key" in Henry's note) in WIDCOMM software? [...]

    Yes, though some substantial info was given in this thread (tnx!), the
    initial question is still open and I'm also interested to find the saved key
    on the Widcomm side. So if anybody knows where to fnd it, please let us
    know, too.

    My reason is similar to Pawels, but I'm intending to use it on the same PC
    and OS, but with a different 'user'. Here's some background why:

    I'm not starting the Widcomm device drivers with the user logon, but already
    with the start of the PC (XP). This is done by starting the BTstackserver
    via the Scheduled Task manager under my user account and pwd with the option
    at startup. Thou pairing of the devices has to be done in a normal
    operational mode with having the GUI enabled prior to this.

    So this give me the option e.g. to surf the web with my Palm even though I
    aven't logged on to my PC, yet. (Having the devices paired is security
    enough IMHO.)

    The disadvantage is that as soon as I change my password I also have to
    change it in the Schedule Task job. So my idea was attach the BTstackserver
    service not to my account, but to e.g. Windows "System" account. As said
    before, the initial pairing has to be done with the GUI enabled, but I can't
    do this as the "System" user.

    So I also was looking to move my account's key into the area for the
    "System" user.
    --
    tnx
    Oliver
  5. Hi!

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


    HKEY_CURRENT_USER\Software\Widcomm\BTConfig\LinkKeys


    Have a nice life :)

    JC
  6. This topic has been closed by Pyree
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