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From:   Alexandre Augusto <alexandre.a.giron@gmail.com>
Date:   Mon, 25 Mar 2019 09:40:04 -0300
Message-ID: <CABLzjm_jO8=vVjSosWh=PjLpoeZuY8BSYPkSxKwomY4AYBPLGA@mail.gmail.com>
Subject: Re: Information about HCI LE Rand command
To:     Emil Lenngren <emil.lenngren@gmail.com>
Cc:     Bluez mailing list <linux-bluetooth@vger.kernel.org>
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Thanks Emil.

The reason I asked is that I am researching ways to provide that
"minimum entropy required", and I was not able to find details about
the number generation.

Best regards,
Alexandre Giron

Em seg, 25 de mar de 2019 =C3=A0s 09:23, Emil Lenngren
<emil.lenngren@gmail.com> escreveu:
>
> Hi Alexandre,
>
> Den m=C3=A5n 25 mars 2019 kl 13:03 skrev Alexandre Augusto
> <alexandre.a.giron@gmail.com>:
> >
> > Hello,
> >
> > I would like to know, if possible, information about the bluez LE Rand
> > command (ocf 0x0018) at HCI code. How does it generate the number? Is
> > it vendor-specific (or secret)?
>
> According to the Bluetooth core specification, it shall be a "A pseudo
> random number generator compliant with [FIPS PUB 140-2]
> (http://csrc.nist.gov/publications/fips/fips140-2/fips1402annexc.pdf)"
> which shall be seeded "with at least the minimum entropy required by
> the pseudo random number generator". What algorithm each Bluetooth
> controller actually uses is therefore vendor specific. I guess most
> controllers will use some SHA-based or AES-based algorithm. Note that
> it is not the host (BlueZ) that generates the number; it just asks the
> controller to generate it for the host.
>
> /Emil


--=20
Alexandre Augusto Giron
Professor da UTFPR