Subject: Re: [pkix] Possible new work item: additional methods for generating key identifiers

From: Peter Gutmann <[email-masked]>
Date: Sat, 03 Jul 2010 22:53:22 +1200

"Miller, Timothy J." <[email-masked]> writes:

>As a result, honoring a requested SKID can exacerbate security
>vulnerabilities--i.e., I request a cert with a SKID that matches the hash-
>derived SKID in your cert, but from a different PKI.  I can then potentially
>authenticate as you to a system that trusts both PKIs but erroneously
>understands the current scope of SKID.

Stefan, do you know if the Adobe PKI uses only the sKID for its path-building?
You mentioned that it requires the sKID to be present, but I'm not sure if
that means it uses the DN as a backup (so more or less the reverse of what
you're supposed to do) or whether it uses only the sKID.  If it relies
entirely on the sKID...

Peter.

---

From: Stefan Santesson <[email-masked]>
Date: Mon, 05 Jul 2010 09:28:00 +0200

Peter,

I think the question is best asked to Adobe.
The only thing I have really tested is that a chain with a mismatching
SKI/AKI is not accepted. I don't know what happens if SKI/AKI is absent so I
have never meant to claim that SKI must be present.

/Stefan

On 10-07-03 12:53 PM, "Peter Gutmann" <[email-masked]> wrote:

> _______________________________________________
> pkix mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/pkix

---

From: Michael StJohns <[email-masked]>
Date: Mon, 05 Jul 2010 20:28:16 -0400

RFC5280, Sect 4.2.1.2: "Applications are not required to verify that key identifiers match when performing certification path validation."

Seems pretty clear to me that the KIDs aren't a security attribute.

Mike

At 12:22 PM 6/24/2010, Miller, Timothy J. wrote:
>>If you authenticated based on a KID match or use a KID as an
>>authorization check, you deserve to be compromised.  KID is solely a
>>path development and validation performance enhancer and not a security
>>attribute of a certificate.
>
>That may be the WG's intent, but IMHO the text isn't clear on the point.  That's why I said it deserves a security note.
>
>-- Tim
>
>