Re: [TLS] [therightkey] Fwd: Improving EV Certificate Security

Joseph Bonneau <jbonneau@gmail.com> Thu, 26 September 2013 05:15 UTC

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From: Joseph Bonneau <jbonneau@gmail.com>
Date: Thu, 26 Sep 2013 01:15:13 -0400
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To: Ben Laurie <benl@google.com>
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Cc: "therightkey@ietf.org" <therightkey@ietf.org>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] [therightkey] Fwd: Improving EV Certificate Security
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I'd like some elaboration on the plan for step 6, creating a whitelist of
valid EV certificates without an SCT. How is this going to be achieved?
Also, if we could do this, why not do it for all certificates and bootstrap
CT that way? Are the parameters of EV special for this (fewer certs, better
records, etc.)?

An alternate approach to a whitelist is to require SCTs for certs with a
"not before" validity period after time T (presumably this requirement
kicksn in around time T). With a stolen/compromised EV CA key you could
still issue a fraudulent cert and backdate it, so you'd have to more
strictly enforce the limits on validity periods for EV certs which I
believe are 27 months in the CA/Browser forum guidelines and 39 months in
the EV code-signing cert proposal. Of course this isn't attractive in that
it means years before you really have protection against fraudulent EV
certs. Has this approach been considered?

Joe