Re: [lamps] Call for adoption of draft-becker-guthrie-cert-binding-for-multi-auth-02

[Mike Ounsworth <[e-mail]>]

Hi Panos,

Mike / Alie / Rebeca should really answer here, but as I've been following this, I'll give it a shot.

You asked:

> In other words, if CertA and CertB were issued separately, why could the verifier not just use the Subject Name or SANs to confirm the certs relationship while verifying?

NSA has said this is for their internal PKIs, they just want an RFC to make cross-vendor implementation easier. I think that's about all the detail they're willing to share as anything more would probably reveal specifics of their private PKI.

My guess is that they're dealing with PIV cards where you may have more than one active card for a given DN / SAN, so they need a way to prove that both private keys reside in the same piece of hardware, which this draft gives them a way to do.

---
Mike Ounsworth

-----Original Message-----
From: Spasm <[e-mail]> On Behalf Of Kampanakis, Panos
Sent: Thursday, January 5, 2023 9:33 PM
To: Russ Housley <[e-mail]>; LAMPS <[e-mail]>
Subject: [EXTERNAL] Re: [lamps] Call for adoption of draft-becker-guthrie-cert-binding-for-multi-auth-02

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My previous objections and concerns have not been addressed, but maybe I had misunderstood the spirit of the draft. So let me repeat the last, most important, question after Mike's presentation of the draft in IETF-115.

It seems that the draft just wants to provide an extension that says cert A and cert B are related and owned by the same entity and allow a CSR to prove that the requester of Cert B also owns the private key for Cert A. In other words the flow would work as:
- Entity X generates a CSR for CertA and proves it owns the private key for A. The issuer generates CertA after verifying the ownership of private key A and the identity of X.
- Entity X generates a CSR for CertB which is related to CertA and proves it owns the private key for A and B. The issuer generates CertB (related-to-CertA) after verifying the ownership of private keys A and B and the identity of X.
- Entity X owns CertA and CertB which it uses to be authenticated in protocol Y. The protocol Y verifier gets CertA and CertB, it verifies the peer owns the private key for CertA, CertB and it confirms it trusts these certs were issued for Entity X.

Now let's forget the draft and say we do not use a new X.509 or CSR extension. And let's say the flow now works as
- Entity X generates a CSR for CertA and proves it owns the private key for A. The issuer generates CertA after verifying the ownership of private key A and the identity of X.
- Entity X generates a CSR for CertB and proves it owns the private key for B. The issuer generates CertB after verifying the ownership of private key B and the identity of X.
- Entity X owns CertA and CertB which it uses to be authenticated in protocol Y. The protocol Y verifier gets CertA and CertB, it verifies the peer owns the private key for CertA, CertB and it confirms it trusts BOTH of these certs were issued for the same entity Entity X.

Why is the former flow better over the latter? In other words, if CertA and CertB were issued separately, why could the verifier not just use the Subject Name or SANs to confirm the certs relationship while verifying?



-----Original Message-----
From: Spasm <[e-mail]> On Behalf Of Russ Housley
Sent: Thursday, January 5, 2023 6:02 PM
To: LAMPS <[e-mail]>
Subject: [EXTERNAL] [lamps] Call for adoption of draft-becker-guthrie-cert-binding-for-multi-auth-02

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Do the changes that were made in -02 of the Internet-Draft resolve the concerns that were previously raised?

On behalf of the LAMPS WG Chairs,
Russ


> On Sep 15, 2022, at 11:44 AM, Russ Housley <[e-mail]> wrote:
>
> There has been some discussion of https://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-becker-guthrie-cert-binding-for-multi-auth/__;!!FJ-Y8qCqXTj2!eoRwxOb953vE83NpPebPNglW-QCy48W1d9auwOVRRsHK0P3CUQil9v2iT8BjDEdle9YlpmtmPm4Iw_vJKyE2TceSUDgbEICFMbx47N_BrA$ .  During the discussion at IETF 114, we agree to have a call for adoption of this document.
>
> Should the LAMPS WG adopt “Related Certificates for Use in Multiple Authentications within a Protocol” indraft-becker-guthrie-cert-binding-for-multi-auth-01?
>
> Please reply to this message by Friday, 30 September 2022 to voice your support or opposition to adoption.
>
> On behalf of the LAMPS WG Chairs,
> Russ
>

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