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

Marsh Ray <marsh@extendedsubset.com> Tue, 13 September 2011 20:04 UTC

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Date: Tue, 13 Sep 2011 15:06:35 -0500
From: Marsh Ray <marsh@extendedsubset.com>
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To: Yoav Nir <ynir@checkpoint.com>
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Cc: IETF WebSec WG <websec@ietf.org>
Subject: Re: [websec] Certificate Pinning via HSTS (.txt version)
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Just thinking out loud here.

On 09/13/2011 01:41 PM, Yoav Nir wrote:
>
> Locking yourself into a CA like that seems like a bad idea. Unlike
> the Dutch government and Mozilla, most customers do not have the pull
> to force CAs to submit to audits.

Or not, like the Dutch government, have the pull to convince Mozilla to 
hesitate for a few days to revoke your pwned CA.

> Six months ago we would not have thought that Comodo or DigiNotar
> were easy to hack. In the latter case, the customers of DigiNotar
> were left out in the cold. Without certificate pinning, they just
> need to spend money on a new certificate and their site is working
> again. With it, they are in trouble.

When would locking yourself into a keypair be any more sensible?

PKI has long history of uncounted thousands of revoked certs, most 
probably for mundane reasons. But a large number of critical cases are 
certainly due to the webserver and private key getting pwned (like 
senate.gov).

What if attacker pwned your web server and configured it to broadcast 
HSTS for a few days, pinning you to the keypair of which they now know 
the private key?

What if they maliciously pinned you to a floundering CA?

Google is one thing, they have their own CA and even their own web browser.

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.

- Marsh