Re: [TLS] The future of external PSK in TLS 1.3

Hannes Tschofenig <Hannes.Tschofenig@arm.com> Wed, 30 September 2020 08:08 UTC

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From: Hannes Tschofenig <Hannes.Tschofenig@arm.com>
To: "Blumenthal, Uri - 0553 - MITLL" <uri@ll.mit.edu>, Watson Ladd <watsonbladd@gmail.com>
CC: "tls@ietf.org" <tls@ietf.org>
Thread-Topic: [TLS] The future of external PSK in TLS 1.3
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Date: Wed, 30 Sep 2020 08:08:33 +0000
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Archived-At: <https://mailarchive.ietf.org/arch/msg/tls/7BrdP7Spo5ZXizxFDfQ6Vb_4fG0>
Subject: Re: [TLS] The future of external PSK in TLS 1.3
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Hi Uri,

I would even argue that key management is less challenging for IoT deployments because devices typically talk to a single device management server only.
So, the communication patterns are pretty simplistic compared to a generic computing device.
RFC 7452 talks about this topic (see the device-to-cloud and device-to-gateway pattern).

Ciao
Hannes

-----Original Message-----
From: TLS <tls-bounces@ietf.org> On Behalf Of Blumenthal, Uri - 0553 - MITLL
Sent: Wednesday, September 30, 2020 2:48 AM
To: Watson Ladd <watsonbladd@gmail.com>
Cc: tls@ietf.org
Subject: Re: [TLS] The future of external PSK in TLS 1.3

Because PSK is one of the affordable and reliable quantum-resistant key exchanges that work *today*? And done environments do not wish to do any EC operations.

Yes, key management issues are real. Those who need it, understand the implications.

Regards,
Uri

> On Sep 29, 2020, at 20:30, Watson Ladd <watsonbladd@gmail.com> wrote:
>
> ´╗┐On Tue, Sep 29, 2020 at 12:49 PM Blumenthal, Uri - 0553 - MITLL
> <uri@ll.mit.edu> wrote:
>>
>> I share Achim's concerns.
>>
>> But I believe the explanations will turn out mostly useless in the real world, as the "lawyers" of the industry are guaranteed to steer away from something "not recommended".
>>
>> In one word: bad.
>
> Why is PSK so necessary? There are very few devices that can't handle
> the occasional ECC operation.  The key management and forward secrecy
> issues with TLS-PSK are real. Steering applications that can afford
> the CPU away from PSK and toward hybrid modes is a good thing and why
> this registry exists imho.
>
>
> --
> Astra mortemque praestare gradatim
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