[riot-devel] [BLE] Random 48-bit address generation

Brett Swann brettswann at gmail.com
Wed Jun 15 15:36:32 CEST 2016


Hi Florent,

A random BD_ADDR is "okay" for testing, but just be aware of the
requirement for an OUI as discussed in BLE Core specification, volume 2,
section 1.2 [1]. Also, steer clear of the reserved range mentioned in
section 1.2.1.

Kind regards,
Brett

[1] https://www.bluetooth.org/docman/handlers/downloaddoc.ashx?doc_id=229737


On Wed, Jun 15, 2016 at 3:27 PM Martine Lenders <mail at martine-lenders.eu>
wrote:

> Hi,
> alternatively, instead of truncating you can just "fold" the remaining
> bytes over using XOR this way you keep some of the variance introduced
> by the longer hash.
>
> Best regards,
> Martine
>
> 2016-06-15 15:12 GMT+02:00 Jose Alamos <jialamos at uc.cl>:
> > Hello,
> >
> > I don't know exactly how the BD_ADDR works, but you might try generate a
> > hash (maybe SHA256? [1]) from CPU ID (function cpuid_get [2]).
> >
> > Then you can truncate to 48 bits and manually set/fix required bytes. Of
> > course the truncation makes the hash weaker in terms of the chances of
> > having 2 same BD_ADDR, but I think that's very unlikely.
> >
> > Best regards.
> >
> >
> > [1] http://riot-os.org/api/sha256_8h.html
> > [2]
> >
> http://riot-os.org/api/group__drivers__periph__cpuid.html#ga562e64bc300b062ac82dac98b8af7cf2
> >
> > _______________________________________________
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> > devel at riot-os.org
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> >
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