Michael Richardson writes:
> 
> Kris Pister <[email protected]> wrote:
>     > Things that a mote might start with (one or more of):
>     > A) nothing
>     > B) PSK(s)
>     > C) raw public/private key
>     > D) certificate(s) from
>     >   i) manufacturer/distributor/installer
>     >  ii) consortium (e.g. Corner Grocers Alliance)
>     > iii) end user/owner (e.g. Charlie's Market)
>     >  iv) desired network(s)
> 
>     > Things that a mote might end with:
>     > 1) L2 key(s) for MIC (and optionally encryption)
>     > 2) DTLS session with JCE if present
>     > 3) DTLS session with PCE if present
>     > 4) L2 keys for 6top communication to neighbors
>     > 5) locally-significant certificate for future joins
> 
> I agree with your characterisation, but (A) can't be correct.
> 
>     > We need a way for people who say "I don't want the hassle of security,
>     > and I can't afford a chip with ECC" (e.g. start state A) to still
>     > transition to something
>     > that is
>     > secure after the join process is over.
> 
> I can design/pick an online protocol where such a device that has been
> provisioned at manufacturing time with a (larger) symmetric key could join.
> To make this work requires that the manufacturer always be online and
> available, that the devices are never resold or repurposed without the
> participation of the manufacturer, and the privacy footprint of the solution
> may poor.  Such a join process may lack PFS, and maybe some forms of replay
> attack may be possible; that suggests that the device, once provisioned may
> never be factory defaultable.
> 
> I would prefer to leave (A) out for now.

Note, that A is from the security point of view, exactly same as
well-known shared key.
-- 
[email protected]

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