Hi Vinicius & All,
I am starting to move forward on the LE Security Manager for bluez. I
am currently using the patches submitted by Vinicius for bluetooth-next,
and hope that they are accepted by Gustavo soon, but at some point, I
will be forced to move forward with or without that acceptance.
My more immediate attention is therefore placed on key storage (LTK,
IRK, CSRK), and high level APIs, in particular Passkey agents for MITM
support.
If anyone is working these problem already, I would like to discuss
details, so that we are not coming up with competing solutions. The
main reason I would like Vinicius' patches accepted sooner rather than
later is so that I (and others) can start contributing these next pieces
without creating a divergence headache.
To begin with, I am planning on making the key storage part of the
existing system used by BR/EDR. I am primarily concerned with Dual Mode
devices, and we believe that from a "big system" point of view, that
most of the differences between remote dual-mode and remote LE-only can
be largely abstracted and out of sight by high level apps. The main
differences between LE keys and BR/EDR keys of course is that there are
multiple keys per "pairs of devices", and except for LTKs, they are used
very differently.
Also, I understand that some people think that Write-Cmd signing (CSRK)
and verification should be a function of GATT/ATT in User space, and
others think it should be handled down in the SM kernel on the way out
(and in). I know that the crypto library is being brought into the
kernel for STK resolution, and this would seem to point towards kernel
based signing and verification.
Privacy is the biggest problem however. Identity *resolution* can of
course be done at the kernel level but if addresses change, we will need
to come up with a plan as to how to deal with everything up to and
including dbus object-paths that currently include an ascii
representation of the BD Addr as part of the path. At the highest
(DBus) level I am thinking that a signal on the original object path
might work when we connect/detect a new address for an existing device,
and an object path which is then an extension of the originally paired
device:
If Original was:
/org/bluez/3456/hci0/dev_XX_XX_XX_XX_XX_XX
The Private could be:
/org/bluez/3456/hci0/dev_XX_XX_XX_XX_XX_XX/priv_YY_YY_YY_YY_YY_YY
Anyway, we are starting work on this soon, so if there is
competing/complimentary work being done, I would really like to hear
from you. There is a lot to be done here, and I'd like to have the
architectural conversations sooner rather than later.
I would also like to hear from you if you simply have a good idea of how
you think these LE pieces should be architected, and haven't started
writing code.
--
Brian Gix
bgix@xxxxxxxxxxxxxx
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
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