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

Michael Richardson <> Wed, 28 August 2019 16:37 UTC

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From: Michael Richardson <>
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Date: Wed, 28 Aug 2019 12:37:01 -0400
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Subject: Re: [Iot-onboarding] what can pinned-domain-cert actually pin?
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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
    > 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 <>ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-