Re: [TLS] Universal PSKs

Matt Caswell <matt@openssl.org> Fri, 15 June 2018 12:00 UTC

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From: Matt Caswell <matt@openssl.org>
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Date: Fri, 15 Jun 2018 13:00:17 +0100
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Subject: Re: [TLS] Universal PSKs
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On 15/06/18 12:37, Nikos Mavrogiannopoulos wrote:
> It feels that's this is too little too late. Implementations which
> support PSKs will switch to TLS1.3 irrespective of this proposal. If
> this proposal takes on, we will have some implementations which support
> universal PSKs and others which don't leading to interoperability
> problems which we wouldn't have otherwise.

I'm not sure how many TLS1.3 implementations there are out there that
also have TLS1.2 PSK support. OpenSSL is one of them. We have APIs for
TLS1.2 PSKs and different APIs for TLS1.3 PSKs. Currently applications
using the old APIs can still expect those PSKs to work in TLS1.3. In
light of this proposal we are considering removing our TLS1.2 -> TLS1.3
PSK code and instead restricting applications using TLS1.2 PSK APIs to
only TLS1.2 until this is resolved (although unfortunately that would
mean removing it from our upcoming LTS release).

Matt