Subject: PKINIT-23 Editorial changes: section 3.2.4: Validation of KDC Reply

From: "Liqiang(Larry) Zhu" <[email-masked]>
Date: Wed, 26 Jan 2005 02:58:53 -0800

In -22, we have

   In either case, the client MUST check to see if the included
   certificate contains a subjectAltName extension of type dNSName or
   iPAddress (if the KDC is specified by IP address instead of name).
   If it does, it MUST check to see if that extension matches the KDC it
   believes it is communicating with, with matching rules specified in
   RFC 2459.  Exception: If the client has some external information as
   to the identity of the KDC, this check MAY be omitted.

   The client also MUST check that the KDC's certificate contains an
   extendedKeyUsage OID of id-pkkdcekuoid:

       { iso(1) org(3) dod(6) internet(1) security(5) kerberosv5(2)
         pkinit(3) pkkdcekuoid(5) }

The "Exception" is well hidden, and I see no reason why the exception is
not applied to the second check.

I propose to re-arrange this to:

   In either case, unless the client has some external information as to
   the identity of the KDC, the client MUST do the following:

   1.  The client checks to see if the included certificate contains a
      subjectAltName extension of type dNSName or iPAddress (if the KDC
      is specified by IP address instead of name).  If it does, it MUST
      check to see if that extension matches the KDC it believes it is
      communicating with, with matching rules specified in [RFC3280].

   2.  The client checks that the KDC's certificate MUST contain an
      extendedKeyUsage OID of id-pkkdcekuoid:

       { iso(1) org(3) dod(6) internet(1) security(5) kerberosv5(2)
         pkinit(3) pkkdcekuoid(5) }

---

From: Sam Hartman <[email-masked]>
Date: Wed, 26 Jan 2005 18:11:52 -0500

>>>>> "Liqiang(Larry)" == Liqiang(Larry) Zhu <[email-masked]> writes:

    Liqiang(Larry)> The "Exception" is well hidden, and I see no
    Liqiang(Larry)> reason why the exception is not applied to the
    Liqiang(Larry)> second check.

    Liqiang(Larry)> I propose to re-arrange this to:

    Liqiang(Larry)>    In either case, unless the client has some
    Liqiang(Larry)> external information as to the identity of the
    Liqiang(Larry)> KDC, the client MUST do the following:

I support the intent of this change although I'm unsure it is
editorial in nature.

I'm a bit concerned by the wording.  Knowing that the KDC is at
10.0.06 is information about its identity.  

I think the case you are interested in is when the client knows the
cryptographic identity of the KDC.

--Sam