Re: [perpass] privacy implications of UUIDs for IoT devices

Joseph Lorenzo Hall <joe@cdt.org> Fri, 07 October 2016 13:49 UTC

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From: Joseph Lorenzo Hall <joe@cdt.org>
Date: Fri, 7 Oct 2016 09:48:37 -0400
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To: Christian Huitema <huitema@huitema.net>
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Cc: Michael Richardson <mcr+ietf@sandelman.ca>, perpass <perpass@ietf.org>
Subject: Re: [perpass] privacy implications of UUIDs for IoT devices
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The Eddystone ephemeral identifier for BLE work from Google may be of
interest to some here (doesn't solve cases of unknown neighbors):
https://developers.google.com/beacons/eddystone-eid

On Thu, Oct 6, 2016 at 9:41 PM, Christian Huitema <huitema@huitema.net>;
wrote:

>
> On Thursday, October 6, 2016 6:58 AM, Michael Richardson wrote:
> >
> > ...
> > I'd love to find a way to send the identifier only to an authorized
> operator,
> > which is resistant to an active MITM, given that the new device (the
> pledge)
> > doesn't know who the authorized operator is yet.
>
> We are looking at that in the pairing draft in DNSSD
> (https://tools.ietf.org/html/draft-kaiser-dnssd-pairing-00). The
> hypothesis
> is that the two paired devices can display a short authentication string,
> e.g. 6-7 digits. Given that, we can establish a TLS connection without
> prior
> credentials between the two parties, with a probability 99.9999% that any
> MITM attempt will be detected. But the two parties have to be able to "see"
> the string display on the other device and compare it to the local one.
> ZRTP
> uses the same algorithm to detect MITM in audio connection, probably
> assuming that the parties will read the string over the audio channel and
> that the MITM cannot really rework the audio in real time.
>
> There is another trick, used in the privacy extensions to DNS-SD
> (https://tools.ietf.org/html/draft-huitema-dnssd-privacy-02). Use TLS PSK,
> or better yet TLS/ECDH/PSK. Instead of PSK ID, send a puzzle that can only
> be solved by parties knowing the PSK, e.g. nonce + hash (nonce, PSK). That
> guarantees connection without MITM, and also without disclosure of the
> identities to third parties. Problem, it scales as O(number of PSK) known
> by
> the server. We could probably devse an extension of that using public key
> technology.
>
> -- Christian Huitema
>
>
>
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>



-- 
Joseph Lorenzo Hall
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