Re: [Iot-onboarding] what can pinned-domain-cert actually pin?

Michael Richardson <mcr+ietf@sandelman.ca> Wed, 28 August 2019 16:37 UTC

Return-Path: <mcr+ietf@sandelman.ca>
X-Original-To: iot-onboarding@ietfa.amsl.com
Delivered-To: iot-onboarding@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 7D22412080E for <iot-onboarding@ietfa.amsl.com>; Wed, 28 Aug 2019 09:37:06 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.199
X-Spam-Level:
X-Spam-Status: No, score=-4.199 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id fv8E3XrA3Iy6 for <iot-onboarding@ietfa.amsl.com>; Wed, 28 Aug 2019 09:37:04 -0700 (PDT)
Received: from tuna.sandelman.ca (tuna.sandelman.ca [IPv6:2607:f0b0:f:3:216:3eff:fe7c:d1f3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id F0A4D1208B1 for <iot-onboarding@ietf.org>; Wed, 28 Aug 2019 09:37:03 -0700 (PDT)
Received: from sandelman.ca (obiwan.sandelman.ca [IPv6:2607:f0b0:f:2::247]) by tuna.sandelman.ca (Postfix) with ESMTP id 384AB3808A for <iot-onboarding@ietf.org>; Wed, 28 Aug 2019 12:35:52 -0400 (EDT)
Received: from localhost (localhost [IPv6:::1]) by sandelman.ca (Postfix) with ESMTP id 6350161 for <iot-onboarding@ietf.org>; Wed, 28 Aug 2019 12:37:01 -0400 (EDT)
From: Michael Richardson <mcr+ietf@sandelman.ca>
To: "iot-onboarding\@ietf.org" <iot-onboarding@ietf.org>
In-Reply-To: <CY4PR1101MB22782817AA5A55C3812A3EEFDBA30@CY4PR1101MB2278.namprd11.prod.outlook.com>
References: <2693.1566923418@localhost> <0100016cd46359e7-8c844438-dc7a-45df-9868-ba0957bcc89f-000000@email.amazonses.com> <CY4PR1101MB22782817AA5A55C3812A3EEFDBA30@CY4PR1101MB2278.namprd11.prod.outlook.com>
X-Mailer: MH-E 8.6; nmh 1.7+dev; GNU Emacs 24.5.1
X-Face: $\n1pF)h^`}$H>Hk{L"x@)JS7<%Az}5RyS@k9X%29-lHB$Ti.V>2bi.~ehC0; <'$9xN5Ub# z!G,p`nR&p7Fz@^UXIn156S8.~^@MJ*mMsD7=QFeq%AL4m<nPbLgmtKK-5dC@#:k
MIME-Version: 1.0
Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature"
Date: Wed, 28 Aug 2019 12:37:01 -0400
Message-ID: <12883.1567010221@localhost>
Archived-At: <https://mailarchive.ietf.org/arch/msg/iot-onboarding/N4AXQy6ox5--x-bg0fNxEQ6mmbo>
Subject: Re: [Iot-onboarding] what can pinned-domain-cert actually pin?
X-BeenThere: iot-onboarding@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Discussion of IoT onboarding mechanisms <iot-onboarding.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/iot-onboarding>, <mailto:iot-onboarding-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/iot-onboarding/>
List-Post: <mailto:iot-onboarding@ietf.org>
List-Help: <mailto:iot-onboarding-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/iot-onboarding>, <mailto:iot-onboarding-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 28 Aug 2019 16:37:12 -0000

Kent wrote:
    >> In SZTP, pinned-domain-cert is the long-lived TA to a potentially short-lived
    >> "Owner Certificate".  In theory, the root of the pinned-domain-cert PKI could
    >> be a public CA but, in practice (because public CAs don't issue long-lived
    >> certs), it means that a private PKI needs to be used.  Due to the nature of
    >> these PKIs NOT being used to secure TLS-based services, the need for
    >> a public root TA isn't there, so no big deal.

    > What do you mean by long-lived? Public CAs can issue EE certs with
    > expiration times up to 825 days as per
    > https://cabforum.org/wp-content/uploads/CA-Browser-Forum-BR-1.6.5.pdf. When
    > thinking about pinned nonceless vouchers for thing onboarding, that's
    > still pretty long. If pinning the EE cert, then the voucher is valid
    > until the EE cert expires (assuming of course that the non-bootstrapped
    > thing has an accurate trusted view of time). If the public CA root is
    > pinned, then that 825 day limit doesn't matter as the public CA root
    > will be long lived. E.g. Lets Encrypt ISRG Root X1 root expires in
    > 2035, but if pinning that then we have the DNS-ID issue.

1) LetsEncrypt does not issue 825 day certificates. (That's 2 1/4 years).

2) I'm not worried about the LE key rolling, because the RFC8649 will likely
   be used.

3) By Long Lived, I mean 10 to 30 years.

--
Michael Richardson <mcr+IETF@sandelman.ca>;, Sandelman Software Works
 -= IPv6 IoT consulting =-