[cabfpub] Private key control

[Ryan Sleevi]

Before you go proposing more requirements just to have more requirements,
which is the unfortunate way I interpret "so we have something to put in
this section", I'd again like to repeat the request that you elaborate on
the threats you believe this addresses.

Surely, if this provides any security value, you can at least elaborate one
or two actual scenarios that you believe the BRs fail to address, and that
this would.

Cheers
On Oct 24, 2014 9:47 AM, "Ben Wilson" <ben.wilson at digicert.com> wrote:

> Bruce,
>
> I assume you’re not opposed to coming up with wording that is less
> specific but would at least eventually fill in content for section 3.2.1 of
> an RFC-3647-formatted CP, which is what I’d like us to be working toward.
>   If we really want to strip this down, even though I think we should
> address the MITM concern, then maybe we could just say something like,
> “Prior to issuing a Certificate, the CA MUST verify that the Applicant
> possesses the Private Key associated with the Public Key to be included in
> the Certificate.  The CA MAY verify this association by obtaining a CSR
> from the Applicant.”  ?
>
>
>
> In other words, I don’t think anyone wants to disrupt internal practices
> of CAs that comply with this textbook CA baseline practice, unless you are
> saying that for the Web PKI, proof of possession isn’t necessary.  If you
> are, then do you have an alternative you could propose?  That’s what I’m
> looking for—something that we can all agree on that will fill a hole.
>
> Thanks,
>
> Ben
>
>
>
>
>
> *From:* public-bounces at cabforum.org [mailto:public-bounces at cabforum.org] *On
> Behalf Of *Bruce Morton
> *Sent:* Friday, October 24, 2014 8:19 AM
> *To:* Rick Andrews; Jeremy Rowley; CABFPub
> *Subject:* Re: [cabfpub] Private key control
>
>
>
> I think the requirement should be dropped.
>
>
>
> If we only validate the signature on the CSR, then we do not know if there
> is a man-in-the-middle. You need some other data.
>
>
>
> If we want to technically validate private key control, then we should
> take some action such as sending the Subscriber some information
> out-of-band for signature. The signature would be compared to the signature
> on the CSR to see if the same key was used.
>
>
>
> The softer way that an OV/EV private key control is confirmed is by
> contacting the Subscriber out of band to confirm that they
> made/authenticate the request. I don’t think this works for DV. It will
> also not work when the Subscriber can approve a certificate issuance with
> dual-factor login.
>
>
>
> I don’t think we should have the requirement unless we suggest methods
> that will actually work for all certificate types and our current
> certificate management methods.
>
>
>
> This requirement is not in the BRs or the EV guidelines and we have not
> been suffering from an incidents, so again, I think the requirement should
> be dropped.
>
>
>
> Bruce.
>
>
>
> *From:* public-bounces at cabforum.org [mailto:public-bounces at cabforum.org
> <public-bounces at cabforum.org>] *On Behalf Of *Rick Andrews
> *Sent:* Thursday, October 23, 2014 2:46 PM
> *To:* Jeremy Rowley; CABFPub
> *Subject:* Re: [cabfpub] Private key control
>
>
>
> Jeremy,
>
>
>
> How about “The CA MAY verify this association by obtaining a CSR from the
> Applicant and validating the signature on the CSR.”
>
>
>
> -Rick
>
>
>
> *From:* public-bounces at cabforum.org [mailto:public-bounces at cabforum.org
> <public-bounces at cabforum.org>] *On Behalf Of *Jeremy Rowley
> *Sent:* Wednesday, October 22, 2014 6:57 PM
> *To:* CABFPub
> *Subject:* [cabfpub] Private key control
>
>
>
> During the Code Signing BR discussion a few weeks ago, we noticed that the
> Baseline Requirements lack a definitive requirement for the CA to confirm
> that the Application is properly associated with the Public Key being
> included in the certificate.  We’d like to remedy this oversight.  What
> does everyone thing about adding a section similar to the following to the
> BRs?
>
> Section 11.1.5    Verification of Key Pair Association
>
> Prior to issuing a Certificate, the CA MUST verify that the Applicant’s
> Private Key is properly associated with the Public Key and a subject name
> to be included in the Certificate. The CA MAY verify this association by
> obtaining a CSR from the Applicant.
>
>
>
> Jeremy
>
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