An Information Model for Kerberos Version 5
draft-ietf-krb-wg-kdc-model-16

[Ballot comment]
Based on the removal of the standard 2119 template and the new text in section, I'm willing to clear the DISCUSS. Given how unusual it is nowadays to have MUST/SHOULD/etc. without 2119, Stephen might decide whether this is worth mentioning to the rest of the IETF, but that's his call. Just a few things that might still be worth some updates:

1. MUST and MAY are used in the introduction before they are defined in section 2. You might just want to avoid them there.

4.2.2: That's a seriously funky construction of English.

4.3: Aside from the adorable use of "MUST NOT REQUIRE" (which should probably be defined in section 2), I agree with Robert that the meaning sentence is a bit obscure.

[Ballot discuss]
Unlike my colleagues, I would really like to have a DISCUSSion about this bizzarre use of 2119. I understand at this point the WG is discussing it internally, so I will not be at all put off if you do not respond to this point until that WG discussion completes. I'll list here the more egregious examples of misuse just so you see what I'm concerned about. Like Robert, I think you are better off using prose than trying to shoehorn alternate meanings into 2119. If you insist on using 2119, I think you are going to need an explanation of how these uses constitute places where they are "required for interoperation or to limit behavior which has potential for causing harm".

1: You jump right into using MAY and MUST before they are even defined in section 2, and I'm not convinced they are either used correctly or are necessary in the Introduction:

  Implementations of this document MAY decide to change the names used
  (e.g. principalName).

How is this describing an interoperation option? Are you trying to warn other implementations that some implementations MAY change names? It doesn't sound like it. 
 
  If so an implementation MUST provide a name to
  name mapping to this document.  In particular schema languages may
  have different conventions for caseing, eg camelCase vs use of '_'
  and '-' to separate 'words' in a name.  Implementations MUST call out
  such conventions explicitly.

So these MUSTs are indicating some sort of documentation requirement in 2119 terms? That seems bizzarre. Prose makes much more sense here.

  Implementations of this document MUST be able to support default
  values for attributes as well as the ability to specify syntax for
  attribute values.

This might be a reasonable use of MUST, but why is it in the Introduction? Is this actually a protocol requirement you expect people to read?

4.1:

  The Principal MUST be implemented in full and MUST NOT be OPTIONAL in
  an implementation

Aside from the novel use of "MUST NOT be OPTIONAL", why is this sentence not redundant? If it's not redundant, I don't understand what it means.

4.1.1.2:

  The Principal MUST NOT be used before this date.  The syntax of the
  attribute MUST be Internet Date/Time Format from [RFC3339].  The
  attribute MUST be single-valued.

Not using the Principal before a date is not a protocol requirement; it's a definition of the attribute. The first sentence should be "This attribute contains the date and time before which the Principal can not be used." Also, the last two sentences specify syntax. The MUSTs add nothing.

Similar problems exist in 4.1.1.3, 4.1.1.4, 4.1.1.6, 4.1.1.7, 4.3.1.5, 4.3.1.6.

4.1.2:

  In typical situations the Principal is
  associated with exactly 1 KeySet but implementations MUST NOT assume
  this case, i.e. an implementation of this standard MUST be able to
  handle the general case of multiple KeySet associated with each
  principal.

The second MUST is right, but the first is not. "Assuming" is not something that needs a protocol requirement keyword.

4.2:

  Implementations
  of this standard MUST facilitate, to the extent possible, an
  administrator's ability to place more restrictive access controls on
  KeySets than on other Principal data, and to arrange for more secure
  backup for KeySets.

I can't figure out how that MUST is actionable. How could you tell if I violated it? Given that it's "to the extent possible", this sounds like at best it's "SHOULD allow an administrator to place...".

4.3.3:

  The security of the keys is an absolute requirement for the operation
  of Kerberos 5.  If keys are implemented adequate protection from
  unauthorized modification and disclosure MUST be available and
  REQUIRED by the implementation.

Leaving aside the missing comma after "implemented", I can't quite figure out what is being REQUIRED of whom in the above sentence. I think the attempt to squeeze 2119 in here is making the sentence convoluted.

4.4:

  Implementations SHOULD implement policy but MAY allow them to be
  OPTIONAL.

I'm having trouble making heads or tails out of the above. Do you mean, "Policy SHOULD be implemented, but their use is OPTIONAL."?

[Ballot comment]
4.2.2: That's a seriously funky construction of English.

4.3: Aside from the adorable use of "MUST NOT REQUIRE", I agree with Robert that the meaning sentence is a bit obscure.

[Ballot comment]
I don't think adding additional load to the meanings of the 2119 terms helped with the precision
or conciseness of the text in this document. For future efforts, please consider using prose
where you need it instead. There are two places where I had to either read multiple times, or just
guess at the intended meaning. Please try to find a way to clarify them.

1) In section 4.1, when you say MUST NOT be OPTIONAL, it took awhile to convince myself that this
was only trying to say the schema must have this as a mandatory element. If it meant more than that,
I didn't take that away.

2) In section 4.3, does the first sentence mean "A schema must make keys an optional element"?
Is it ok for the schema to not represent keys at all? Is it OK for the interface to not represent keys
even if the schema does? (I realize that's not what reasonable interfaces would do, but the way the
requirements language here is constructed, the sentence as written could be read to say that's ok.)

[Ballot comment]
Thanks for a readable document and for doing the important work of
writing an information model rather than a data model.

I have only a number of petty nits...

---

I do agree wit others' comments about uppercase and pseudo-2119
langauge. At least his could be tidied up a bit. For example, "MUST NOT
be OPTIONAL" is a lovely mixture :-)

---

Abstract should say what a KDC is.

---

Please decide "kerberos" or "Kerberos"

---

  The Kerberos version 5 authentication service described in [RFC4120]
  describes how a Key Distribution Center (KDC) provides authentication
  to clients.  The standard does not stipulate how a KDC is managed and

RFC 4120 is not a standard in the IETF sense of the word.
Maybe s/The standard/RFC 4120/

---

I am not convinced that Section 5 adds to this document, and I can
believe that it might confuse the reader and potentially lead to a
restricted view of implementation options.

If it were to be enitely deleted, I would not miss it.

[Ballot comment]
These are non-blocking, but please consider them seriously, and feel free to
chat with me about them:

I find Section 2 to be rather odd.  I don't like the way you say that the terms are used as defined in 2119, and then go on to say, "Oh, but they're really not, and here's what we mean."  I would *greatly* prefer that you eliminate the 2119 boilerplate and reference, and simply define the terms here, as you mean them.

-- Section 4.1 --

  The Principal MUST be implemented in full and MUST NOT be OPTIONAL in
  an implementation

I think the combination of not-really-2119 terms here is confusing: "MUST NOT be OPTIONAL".  Maybe the right fix here is just to use lower-case "optional".  Or, better, maybe just this: "The Principal MUST be implemented in full, as a required part of every implementation."

-- Section 4.3 --

Similarly, make "MUST NOT REQUIRE" into "MUST NOT require", probably.

IANA has reviewed draft-ietf-krb-wg-kdc-model-12 and has the following comments:

IANA has a question about the IANA Actions requested in this document.

IANA understands that, upon approval of this document, there are five actions which IANA must complete.

In the SMI Network Management MGMT Codes Internet-standard MIBsubregistry
of the Network Management Parameters registry located at:

http://www.iana.org/assignments/smi-numbers

a new subregistry will be created as follows:

Registry Name: [ see question below ]
Reference: [ RFC-to-be ]
Registration Procedures: [ see question below ]

Prefix: iso.org.dod.internet.security.kerberosV5.policies (1.3.6.1.5.2.5)

IANA Question -> What should the new subregistry be named?
IANA Question -> What are the registration procedures for new entries in the
newly created subregisty?

In the newly created (see above) subregistry of the SMI Network Management MGMT
Codes Internet-standard MIBsubregistry of the Network Management Parameters
registry located at:

http://www.iana.org/assignments/smi-numbers

four new MIB will be registered as follows:

Decimal: [ TBD by IANA at time of registration ]
Name: [ see question below ]
Description: Password Quality Policy
References: [ RFC-to-be ]

Decimal: [ TBD by IANA at time of registration ]
Name: [ see question below ]
Description: Password Management Policy
References: [ RFC-to-be ]

Decimal: [ TBD by IANA at time of registration ]
Name: [ see question below ]
Description: Keying Policy
References: [ RFC-to-be ]

Decimal: [ TBD by IANA at time of registration ]
Name: [ see question below ]
Description: Ticket Flag Policy
References: [ RFC-to-be ]

IANA Question -> For each of the MIbs being proposed above, what is
the short name to be used for the MIB?

IANA notes that the authors have suggested values for each of the four MIBs in the document.

IANA understands that these are the only actions required of IANA upon approval of this document.

Note: The actions requested in this document will not be completed until the document has been approved for publication as an RFC.  This message is only to confirm what actions will be performed.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Subject: Last Call:  (An information model for Kerberos version 5) to Proposed Standard


The IESG has received a request from the Kerberos WG (krb-wg) to consider
the following document:
- 'An information model for Kerberos version 5'
  as Proposed Standard

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
ietf@ietf.org mailing lists by 2012-06-12. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  This document describes an information model for Kerberos version 5
  from the point of view of an administrative service.  There is no
  standard for administrating a kerberos 5 KDC.  This document
  describes the services exposed by an administrative interface to a
  KDC.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-krb-wg-kdc-model/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-krb-wg-kdc-model/ballot/


No IPR declarations have been submitted directly on this I-D.

(1.a) Who is the Document Shepherd for this document? Has the
Document Shepherd personally reviewed this version of the
document and, in particular, does he or she believe this
version is ready for forwarding to the IESG for publication?

>> The Document Shepherd for this document is Jeffrey Hutzelman,
>> . I have reviewed this document, and I believe
>> it is ready for IETF-wide review and publication as a
>> Proposed Standard.

(1.b) Has the document had adequate review both from key WG members
and from key non-WG members? Does the Document Shepherd have
any concerns about the depth or breadth of the reviews that
have been performed?

>> This document has received extensive review within the
>> working group, including multiple last calls, each of
>> which generated additional comments. It has been reviewed
>> by WG participants familiar with several possible schema
>> languages. Any issues raised have been resolved.

(1.c) Does the Document Shepherd have concerns that the document
needs more review from a particular or broader perspective,
e.g., security, operational complexity, someone familiar with
AAA, internationalization or XML?

>> I don't believe any particular additional review is required.
>> Of course, more review is always welcome.

(1.d) Does the Document Shepherd have any specific concerns or
issues with this document that the Responsible Area Director
and/or the IESG should be aware of? For example, perhaps he
or she is uncomfortable with certain parts of the document, or
has concerns whether there really is a need for it. In any
event, if the WG has discussed those issues and has indicated
that it still wishes to advance the document, detail those
concerns here. Has an IPR disclosure related to this document
been filed? If so, please include a reference to the
disclosure and summarize the WG discussion and conclusion on
this issue.

>> I have no concerns.
>> No IPR disclosures related to this document have been filed.

(1.e) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with
others being silent, or does the WG as a whole understand and
agree with it?

>> There is concensus within the working group to publish this
>> document. This document has proceeded slowly and, as noted
>> above, there were several last calls, primarily because there
>> were few comments on the meat of the document between last
>> calls. However, there was extensive discussion at various
>> times on what the model should cover and what uses it should
>> aim to support.

(1.f) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in
separate email messages to the Responsible Area Director. (It
should be in a separate email because this questionnaire is
entered into the ID Tracker.)

>> There have been no such expressions of discontent.

(1.g) Has the Document Shepherd personally verified that the
document satisfies all ID nits? (See
http://www.ietf.org/ID-Checklist.html and
http://tools.ietf.org/tools/idnits/). Boilerplate checks are
not enough; this check needs to be thorough. Has the document
met all formal review criteria it needs to, such as the MIB
Doctor, media type and URI type reviews?

>> This document has been run through the idnits tool, and was
>> reviewed manually for compliance with requirements not checked
>> by the automatic tool. No additional formal review criteria
>> apply to this document.

(1.h) Has the document split its references into normative and
informative? Are there normative references to documents that
are not ready for advancement or are otherwise in an unclear
state? If such normative references exist, what is the
strategy for their completion? Are there normative references
that are downward references, as described in [RFC3967]? If
so, list these downward references to support the Area
Director in the Last Call procedure for them [RFC3967].

>> References have been split appropriately. There are no
>> normative downward references or normative references to
>> documents that are not ready for advancement. However,
>> there is an informative reference to a WG document which
>> has been stalled for some time, and some work may be needed
>> to rework text around mentions of that work-in-progress
>> if references to it are to be removed.

(1.i) Has the Document Shepherd verified that the document IANA
consideration section exists and is consistent with the body
of the document? If the document specifies protocol
extensions, are reservations requested in appropriate IANA
registries? Are the IANA registries clearly identified? If
the document creates a new registry, does it define the
proposed initial contents of the registry and an allocation
procedure for future registrations? Does it suggest a
reasonable name for the new registry? See [RFC2434]. If the
document describes an Expert Review process has Shepherd
conferred with the Responsible Area Director so that the IESG
can appoint the needed Expert during the IESG Evaluation?

>> This document requires no IANA actions per se. However,
>> it needs to create a new OID arc under
>> iso.org.dod.internet.security.kerberosV5, for which we
>> believe the security AD's to be authoritative.

(1.j) Has the Document Shepherd verified that sections of the
document that are written in a formal language, such as XML
code, BNF rules, MIB definitions, etc., validate correctly in
an automated checker?

>> No part of this document is written in a formal language
>> requiring such verification.

(1.k) The IESG approval announcement includes a Document
Announcement Write-Up. Please provide such a Document
Announcement Write-Up? Recent examples can be found in the
"Action" announcements for approved documents. The approval
announcement contains the following sections:


Technical Summary

This document describes an information model for Kerberos version 5
from the point of view of an administrative service. There is no
standard for administrating a kerberos 5 Key Distribution Center
(KDC). This document describes the services exposed by an
administrative interface to a KDC.

Working Group Summary

This document represents the consensus of the Kerberos Working Group.
and will serve as the basis for further development of an LDAP schema.


Document Quality

As an information model, this document does not specify anything
that can be directly implemented. Rather, it forms the basis for
further work, such as the production of an LDAP schema which can be
used to support administration of a Kerberos KDC. Producing such
a schema is a chartered work item of the Kerberos Working Group.

In addition, while this document is not necessarily intended to
serve as a basis for KDC database design, it has been informed by
the design of several implementations, including some which are
able to use LDAP as a data store for the KDC database.

Personnel

The Document Shepherd for this document is Jeffrey Hutzelman.
The responsible Area Director is Stephen Farrell.