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From: Luiz Augusto von Dentz <>
To: Vinicius Costa Gomes <>
Cc: Brian Gix <>,
Subject: Re: LE Kernel (bluetooth-le-2.6) and LE Security Manager
Date: Tue, 25 Jan 2011 10:35:19 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20110124213429.GA15121@piper>

Hi Vinicius,

On Mon, Jan 24, 2011 at 11:34 PM, Vinicius Costa Gomes
<> wrote:
> Hi Brian,
> On 11:03 Mon 24 Jan, Brian Gix wrote:
>> Hi Vinicius,
>> I am sorry that it has taken so long to test the snapshot that you
>> placed on gitorious, but I have now done so.
>> On Fri, 2010-12-03 at 19:05 -0300, Vinicius Costa Gomes wrote:
>> > Hi Brian,
>> >
>> > On 11:11 Fri 03 Dec, Brian Gix wrote:
>> > >
>> > > Hi Claudio, Johan & All,
>> > >
>> > > Is this LE capable kernel that Ville is working on, the development stream
>> > > for the LE Security Manager?  And if so, is it in a partial fleshed out
>> > > state?
>> >
>> > There is a simple implementation of SMP here[1] on my "devel" branch. I am
>> > cleaning it up for sending it for review.
>> >
>> > If you want to help, have any comments or just want to tell us what you are
>> > working on, please drop by #bluez on freenode, or send an email.
>> I have been able to verify that the Just Works negotiation of the Short
>> Term Key does work against an independent implementation of the LE
>> Security Manager, as long as I have requested no MITM protection.  I
>> have the following comments:
>> 1. You currently reject security if I *do* request MITM protection.
>> This should not be done.  The correct functionality should be to
>> continue the negotiation.  Even though I requested MITM, it will be
>> clear to both sides that JUST_WORKS methodology has been used, and so
>> when the Keys are generated and exchanged, both sides will indicate in
>> their Key Database that they are no-MITM keys. If I then actually
>> *needed* MITM protection, then whatever functionality requiring that
>> level of security will fail with an insufficient security error code.
>> However, security should *never* be rejected unless there is a
>> fundamental incompatibility such as no level of security actually
>> supported.  This is the only functionality that I found to be actually
>> incorrect.
> I was assuming that the meaning of setting the MITM protection bit, was that
> it was *requiring* MITM protection, and when that couldn't be fulfilled the
> Pairing Request should be rejected.
> So my assumption was incorrect, going to fix it soon.

Well the spec says it is a requirement:

"If the STK generation method does not result in an STK that provides
sufficient security properties then the device shall send the Pairing
Failed command with the error code “Authentication Requirements”" - Selecting STK Generation Method - Page 608

In my interpretation this is exactly what should happen when MITM is
set but there is no way to generate an authenticated key as Table 2.4:
Mapping of IO Capabilities to STK Generation Method suggest, in other
words if one of sides has NoInputNoOutput and MITM is set we should
return "Authentication Requirements" error.

Luiz Augusto von Dentz
Computer Engineer

  reply	other threads:[~2011-01-25  8:35 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-03 19:11 LE Kernel (bluetooth-le-2.6) and LE Security Manager Brian Gix
2010-12-03 22:05 ` Vinicius Costa Gomes
2010-12-04  0:40   ` Brian Gix
2010-12-06 14:50     ` Vinicius Costa Gomes
2011-01-24 19:03   ` Brian Gix
2011-01-24 20:09     ` Luiz Augusto von Dentz
2011-01-24 20:33       ` Brian Gix
2011-01-24 21:34     ` Vinicius Costa Gomes
2011-01-25  8:35       ` Luiz Augusto von Dentz [this message]
2011-01-25 16:58         ` Brian Gix
2011-01-25 17:10           ` Brian Gix
2011-01-25 17:59           ` Johan Hedberg
2011-01-25 18:35             ` Brian Gix
2011-01-25 21:44               ` Luiz Augusto von Dentz
2011-01-25 22:04                 ` Brian Gix
2011-01-26 17:54                   ` Brian Gix
2011-01-28 23:19       ` GATT and D-Bus Inga Stotland
2011-01-29  0:07         ` Vinicius Costa Gomes

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