[dane] draft-ietf-dane-srv-03.txt: name checks, ...

Viktor Dukhovni <viktor1dane@dukhovni.org> Thu, 19 December 2013 17:30 UTC

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From: Viktor Dukhovni <viktor1dane@dukhovni.org>
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Subject: [dane] draft-ietf-dane-srv-03.txt: name checks, ...
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On Thu, Dec 19, 2013 at 08:07:10AM -0800, internet-drafts@ietf.org wrote:

> 	Filename        : draft-ietf-dane-srv-03.txt
> 	Date            : 2013-12-13

Section 5 (no exception for usage 3):
Section 7 (MUST and SHOULD on server name are too strong):
Section 10.3 (no exception for usage 3):

This still conflicts with the smtp-with-dane and ops drafts with
respect to name checks (server identity checks) in usage 3.  In
the two conflicting documents usage 3 certificates are validated
exclusively by matching against DANE TLSA RRs.  No name checks,
key usage checks, expiration checks, ... apply with usage 3.  Rather,
the binding of the EE certificate to the service end-point is
entirely established by the DNSSEC TLSA record (also its validity
lifetime is the lifetime of the TLSA record).

Correspondingly, all requirements on the content of the server
certificate are relaxed with usage 3, it may, if desired, contain
no identity information.  For example, given the following TLSA

    _25._tcp.mail.example. IN TLSA 3 1 1 \
	4D8CC746810AB5C7D7D24EE2A78AA6D5 \

the below would be a valid certificate (which is, absent DANE,
anonymous and never valid):

        Version: 3 (0x2)
        Serial Number: 1 (0x1)
        Signature Algorithm: ecdsa-with-SHA256
            Not Before: Dec 19 17:16:51 2013 GMT
            Not After : Dec 18 17:16:51 2013 GMT
        Subject Public Key Info:
            Public Key Algorithm: id-ecPublicKey
                Public-Key: (256 bit)
                ASN1 OID: prime256v1
    Signature Algorithm: ecdsa-with-SHA256