Re: [TLS] prohibit <1.2 on clients (but allow servers) (was: prohibit <1.2 support on 1.3+ servers (but allow clients))

Geoffrey Keating <geoffk@geoffk.org> Fri, 22 May 2015 17:22 UTC

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To: Peter Gutmann <pgut001@cs.auckland.ac.nz>
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From: Geoffrey Keating <geoffk@geoffk.org>
Date: 22 May 2015 10:22:06 -0700
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Subject: Re: [TLS] prohibit <1.2 on clients (but allow servers) (was: prohibit <1.2 support on 1.3+ servers (but allow clients))
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Peter Gutmann <pgut001@cs.auckland.ac.nz>; writes:

> You know the PLC I used as an example in an earlier message, the one
> that rejects any attempt at connecting with a version number set to
> greater than TLS 1.0?  The "upgrade" procedure for that is to
> replace it when the hardware dies, with a minimum (minimum, not
> maximum) lifetime of around ten years (I've seen refridgerator-sized
> PLCs dating from the 1960s still in active use today, but that's
> because they're practically indestructible compared to modern
> versions).
> 
> So if some sort of BCP is published, it should explicitly target
> browsers and web servers where this kind of upgrade/change is
> possible.  Telling people to throw away their PLCs and replace them
> with new ones isn't going to fly.

Telling people that these PLCs are secure and everything is fine and
they don't need to worry won't fly either.  The owners of these
devices are going to have to find a solution, whether it's an early
hardware upgrade, firmware replacement, or a front-end
translator/firewall.