Subject: Re: Second Last Call: draft-saintandre-tls-server-id-check (Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)) to BCP

From: SM <[email-masked]>
Date: Tue, 07 Dec 2010 13:36:43 -0800

At 04:36 18-11-10, The IESG wrote:
>The IESG has received a request from an individual submitter to consider
>the following document:
>
>- 'Representation and Verification of Domain-Based Application Service
>    Identity within Internet Public Key Infrastructure Using X.509 (PKIX)
>    Certificates in the Context of Transport Layer Security (TLS) '
>    <draft-saintandre-tls-server-id-check-11.txt> as a BCP
>
>The IESG plans to make a decision in the next few weeks, and solicits
>final comments on this action.  Please send substantive comments to the

In Section 2.2:

    'A "traditional domain name", i.e., a fully-qualified domain name
     or "FQDN" (see [DNS-CONCEPTS]) all of whose labels are "LDH
     labels" as defined in [IDNA-DEFS].'

It would be better to reference RFC 1123 for LDH labels instead of 
RFC 5890 unless the authors would like to adopt a terminology that is 
specific to IDNA.

In Section 3.1:

   "Unless a profile of this specification allows continued support
    for the wildcard character '*', the fully-qualified DNS domain
    name portion of a presented identifier SHOULD NOT contain the
    wildcard character, whether as the complete left-most label
    within the identifier (following the definition of "label" from
    [DNS], e.g., "*.example.com") or as a fragment thereof (e.g.,
    *oo.example.com, f*o.example.com, or foo*.example.com)."

If the presented identifier is a fully-qualified DNS domain name (I 
assume that means FQDN), the left-most label cannot be a wildcard 
character according to LDH rules.  I suggest rewriting that as:

    Unless a profile of this specification allows continued support
    for the wildcard character '*', the domain name portion of
    a presented identifier SHOULD NOT contain the wildcard character
    (e.g., "*.example.com") or as a fragment thereof (e.g.,
    *oo.example.com, f*o.example.com, or foo*.example.com).

In Section 4.2.1:

   "The client might need to extract the source domain and service type
    from the input(s) it has received.  The extracted data MUST include
    only information that can be securely parsed out of the inputs (e.g.,
    extracting the fully-qualified DNS domain name from the authority
    component of a URI or extracting the service type from the scheme of
    a URI) or information for which the extraction is performed in a
    manner that is not subject to subversion by network attackers (e.g.,
    pulling the data from a delegated domain that is explicitly
    established via client or system configuration, resolving the data
    via [DNSSEC], or obtaining the data from a third-party domain mapping
    service in which a human user has explicitly placed trust and with
    which the client communicates over a connection that provides both
    mutual authentication and integrity checking)."

I read part of the above as meaning that data can only be extracted 
from DNS if the data has been resolved via DNSSEC.  Is that the intent?

Section 4.3 discusses about how to seek a match against the list of 
reference identifiers.  I found the thread at 
http://www.ietf.org/mail-archive/web/certid/current/msg00318.html informative.

In Section 4.4.3:

   "A client employing this specification's rules MAY match the reference
    identifier against a presented identifier whose DNS domain name
    portion contains the wildcard character '*' as part or all of a label
    (following the definition of "label" from [DNS])"

According to the definition of label in RFC 1035, the wildcard 
character cannot be part of a label.  I suggest removing the last 
part of that sentence.  FWIW, RFC 4592 updates the wildcard 
definition in RFC 1034 and uses the term "asterisk label".

Was the comment about the security note ( 
http://www.ietf.org/mail-archive/web/certid/current/msg00427.html ) 
in Section 4.6.4 addressed?

Regards,
-sm