Subject: Storing Certificates in the DNS (draft-ietf-dnsext-rfc2538bis-08)

From: Russ Housley <[email-masked]>
Date: Mon, 10 Oct 2005 14:25:12 -0400

Please take a look at draft-ietf-dnsext-rfc2538bis-08.  It is on the agenda 
for the IESG telechat this Thursday.  If anyone has any concerns, please 
notify me by Wednesday.

Russ

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From: Tom Gindin <[email-masked]>
Date: Wed, 12 Oct 2005 18:38:58 -0400

Russ:

        Are there any guidelines for CRL owner names, since they're 
covered in the draft although DNS distribution points aren't detailed in 
RFC 3280?  If there aren't any, IMHO a reasonable rule would be that if 
any sequence member of the distribution point name is a domain name (not a 
URI), that should be used.  Also (and lower in precedence), if any 
sequence member of the distribution point name is an RFC 822 address, its 
standard translation should be used.  I doubt if URI's will work without 
conflicts.
        I don't know if these count as "concerns". 

                Tom Gindin
P.S.    The opinions above are mine, and not necessarily those of my 
employer.

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From: Russ Housley <[email-masked]>
Date: Thu, 13 Oct 2005 11:30:04 -0400

Tom:

Thanks for the review.  I do not think that this kind of guidance belongs 
in draft-ietf-dnsext-rfc2538bis, but it does belong in 3280bis.

Russ

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From: Tom Gindin <[email-masked]>
Date: Fri, 14 Oct 2005 07:50:52 -0400

Russ:

        In the current 2538-bis draft, section 2 contains OID's for both 
certificates and CRL's (although not AC's), while section 3 profiles owner 
names for certificates and not for CRL's.  Does this really make sense, 
especially given that there doesn't seem to be any place where owner names 
for CRL's are profiled?
        Also, I think we all realize that most current certificates don't 
fit in 512 bytes, and if the size of standard RSA keys increases the 
certificates will grow more since every certificate contains both a 
subject public key and a signature whose size is no smaller than the CA's 
key.  CRL's actually fit better (a sample one I have with a 1024-bit key 
has a size of about 350 bytes + 37 bytes for each entry, changing to 39 
for revocation times after 2000), but they have to be distribution point 
CRL's and they have to be quite small.  If Phill's point about MTU size is 
relevant, a CRL with more than about 30 entries revoked won't fit into 
that window - and that doesn't guarantee that 30 will.

                Tom Gindin

Russ Housley <[email-masked]>
10/13/2005 11:30 AM
 
        To:     Tom Gindin/Watson/IBM@IBMUS
        cc:     [email-masked], [email-masked]
        Subject:        Re: Storing Certificates in the DNS 
(draft-ietf-dnsext-rfc2538bis-08)

Tom:

Russ

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From: Simon Josefsson <[email-masked]>
Date: Fri, 14 Oct 2005 14:34:23 +0200

> especially given that there doesn't seem to be any place where owner names 

If CERT RR are to be used by PKIX, I believe you would need an PKIX
Operational Protocols for DNS, such as:

http://josefsson.org/rfc2538bis/draft-josefsson-pkix-dns-00.txt

That document should mandate exact owner name rules used for
particular applications, and could describe how CRLs stored in DNS
would be used.  I don't think that kind of detail should go into RFC
2538bis.  Your concerns would be applicable to that document.

> that window - and that doesn't guarantee that 30 will.

The document address this problem through the IPKIX type.

Thanks,
Simon

---

From: Tom Gindin <[email-masked]>
Date: Sun, 16 Oct 2005 16:08:00 -0400

Simon:

        Given the way that distribution points work, I don't understand 
the point of using IPKIX for CRL's with distribution points.  Shouldn't 
the distribution point contain the URL anyway, and if so what good is the 
extra DNS step?  I guess it might be useful for some non-distribution 
point CRL's (mainly those with issuer alternate names), but for 
distribution point CRL's it gains a little flexibility at the cost of both 
security and performance.  I must defer to other members of the PKIX WG as 
to how frequently a CRL has an issuer alternate name without any 
distribution points, as I myself have no recollection of ever seeing such 
a CRL.
        My original reason for commenting was that 2538-bis has owner name 
rules for certificates, but not for CRL's, while section 2.3 lists both 
CRL's and certificates as permitted OID's which are apparently intended 
for the PKIX type.  CRL rules would seem to be less application-specific 
than TLS or S/MIME, and thus more appropriately found in 2538-bis or 
3280-bis than anywhere else.  You have adopted the three 
application-specific guidelines from draft-josefsson-pkix-dns-00.txt in 
2538-bis, even though I don't see why any SSL or TLS client would use the 
DNS to fetch a server certificate when it's exchanged within the protocol 
anyway.  IMHO S/MIME certificates in the DNS are more likely to be useful.
        On a lower level, the binary coding in 2.3 makes little sense. 
Either it's 06 03 55 04 nn, or it's just 55 04 nn - in either case a 
leading x makes sense, but not in front of the length.

                Tom Gindin

Simon Josefsson <[email-masked]>
10/14/2005 08:34 AM
 
        To:     Tom Gindin/Watson/IBM@IBMUS
        cc:     Russ Housley <[email-masked]>, [email-masked]
        Subject:        Re: Storing Certificates in the DNS 
(draft-ietf-dnsext-rfc2538bis-08)

Thanks,
Simon

>>any sequence member of the distribution point name is a domain name (not 

> a