Re: [websec] Certificate Pinning via HSTS (.txt version)

Chris Palmer <> Tue, 13 September 2011 20:59 UTC

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Date: Tue, 13 Sep 2011 13:35:47 -0700
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From: Chris Palmer <>
To: Marsh Ray <>, IETF WebSec WG <>
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Subject: Re: [websec] Certificate Pinning via HSTS (.txt version)
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On Tue, Sep 13, 2011 at 1:06 PM, Marsh Ray <> wrote:

> Q: What kind of pinning would we recommend to our friend or family member
> who runs his business on the web?
> Right now he has his domain registration and cert from GoDaddy.

They could also buy a cert from StartSSL, and keep it on a USB token
in a safe, in case of emergency. I.e., everyone who does pinning
should have a backup pin.

But, currently, we are saying this about that:

"""Deploying certificate pinning safely will require operational and
organizational maturity due to the risk that HSTS Hosts may "brick"
themselves by pinning to a certificate that becomes invalid."""

"""The disaster recovery plans described above all incur new costs for
site operators, and increase the size of the certificate
market. Arguably, well-run sites had already absorbed these costs
because (e.g.) backup certificates from different CAs were necessary
disaster recovery mechanisms even before certificate pinning. Small
sites — which although small might still need to provide good
security — may not be able to afford the disaster recovery mechanisms
we recommend. (The cost of the backup certificate is not the issue; it
is more the operational costs in safely storing the backup and testing
that it works.) Thus, low-risk pinning may be available only to large
sites; small sites may have to choose no pinning or potentially
bricking their site (up to the maxAge window). This is not worse than
the status quo."""