Subject: [dane] Clarity in S 4

From: Eric Rescorla <[email-masked]>
Date: Sun, 13 Nov 2011 16:51:44 -0800

I've just read draft-ietf-dane-protocol-09 and I'm not finding S 4.4
as clear as one might like. In particular, it's not clear to me
whether the checks prescribed here replace the PKIX checks or are
added to the PKIX checks. Based on S 4.2, it appears to be the case
that it depends on the reference type?

Here's what I *think* this document says (ignoring the issue of
the SAN/CN check):

- With certificate type 1, the certificate is accepted iff
  the terminal certificate matches the TLSA RR. Specifically,
  PKIX verification is not done.

- With certificate type 2, there are two cases:
  + With reference type 0, the certificate is accepted iff
    the terminal cert chains to the the cert in the TLSA
    record.
  + With reference type != 0, the certificate is accepted
    if the terminal cert chains to the cert in the TLSA record
    *or* if it would otherwise chain to an existing trust
    anchor

- With certificate type 3, the certificate is accepted iff
  the public key in the TLSA record appears in one of the
  certificates received from the server. [*] This is true
  regardless of whether the certificate chains to an
  existing trust anchor?

Is this interpretation correct?

-Ekr

[*] Note that this is probably too loosely worded in that
it does not appear to require any check of the chain proper,
leaving open the possibility that the terminal cert does
not acually chain to the matching cert, which is especially
relevant as some TLS stacks will process certs received
out of order.

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From: Stephane Bortzmeyer <[email-masked]>
Date: Mon, 14 Nov 2011 12:03:57 +0100

On Sun, Nov 13, 2011 at 04:51:44PM -0800,
 Eric Rescorla <[email-masked]> wrote 
 a message of 44 lines which said:

> I've just read draft-ietf-dane-protocol-09 

The current version is -12 and the numbers of certificate types are
not the same... 

The document is now so different it is probably better to restart from
-12.

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From: Eric Rescorla <[email-masked]>
Date: Mon, 14 Nov 2011 03:06:23 -0800

> The document is now so different it is probably better to restart from

Oops. Don't know how I screwed that up. Will reread.