Distributing a Symmetric Fast Mobile IPv6 (FMIPv6) Handover Key Using SEcure Neighbor Discovery (SEND)
draft-ietf-mipshop-handover-key-03

[Ballot comment]
From Gen-ART Review from Miguel Garcia.

  The Abstract is way too long, and goes way beyond the 5-10 lines that
  the RFC Editor recommends.

  Please expand acronyms at the first occurrence. For example, CGA is
  not written immediately after "Cryptographically Generated Address".
  Other terms, such as "MAC" are never expanded.

  The second author's affiliation is incorrect, so is his email address.

[Ballot comment]
The Abstract is way too long, and goes way beyond the 5-10 lines that
  the RFC Editor recommends.

  Please expand acronyms at the first occurrence. For example, CGA is
  not written immediately after "Cryptographically Generated Address".
  Other terms, such as "MAC" are never expanded.

  The second author's affiliation is incorrect, so is his email address.

IANA Last Call comments:

Upon approval of this document, the IANA will make the following assignments in the "ICMPv6 TYPE NUMBERS" registry located at
http://www.iana.org/assignments/icmpv6-parameters
sub-registry "IPv6 NEIGHBOR DISCOVERY OPTION FORMATS"

(AUTHORS: please confirm that we've identified the correct sub-registry.)

Type Description Reference
---- ----------- ---------
TDB-1 Handover Key Request Option [RFC-ietf-mipshop-handover-key-03]
TDB-2 Handover Key Reply Option [RFC-ietf-mipshop-handover-key-03]

We understand the above to be the only IANA Action for this document.

I reviewed this specification. It is mostly in very good shape,
but there were a few issues. I'd like to discuss them before
moving forward -- and a new draft revision may be needed.

> The MN can reuse the key pair on different
> access routers but MUST NOT use the key pair for
> any other encryption or for signature operation.

I hope this does not imply that the same key pair could not be
used for SEND. Essentially, this would mean that SEND and
FMIP are incompatible. OTOH, I see no reason why this should
apply to anything involving the CGA address itself. Suggested
rewrite:

The MN can reuse the key pair on different
access routers but MUST NOT use the key pair for
any encryption or signature beyond operations
involving the given CGA address (such as Neighbor
Advertisements for the given address, secured
with SEND).


> The AR MUST use its CGA as the source address for the
> PrRtAdv and include a SEND CGA Option and a SEND Signature
> Option with the SEND signature of the message.

This is unusual and unexpected compared to what one would
do in SEND. CGA does not help you protect against someone
pretending to be a router. I would suggest a mechanisms similar
to SEND be applied here, i.e., router side is protected with
trusted root configuration in the mobile nodes and certificates
assigned to each router. This is similar to how TLS works for web,
and is fairly easily deployable.

> The handover key MUST be stored by the AR
> for  future  use,  indexed  by  the  CGA,  and  the  authentication
> algorithm type (i.e., the resolution of the AT field processing)
> and HK-LIFETIME MUST be recorded with the key.
...
> To avoid
>      state depletion attacks, the handover key MUST NOT be generated
>      prior to SEND processing that verifies the originator of RtSolPr.
>      State depletion attacks are possible if this ordering is not
>      respected.

The last statement is not true. Any number of hosts may appear on the link,
existing hosts may generate O(2^64) addresses and demand keys for them,
etc.

The document does not need a big change to fix this, though. Basically
s/MUST/SHOULD/ in the first piece of text, and then some explanation
of how to deal with state depletion in the second piece.

> Upon receipt of one or more PrRtAdvs secured with SEND and having
> the Handover Key Reply Option, the MN MUST first validate the
> PrRtAdvs  as  described  in  RFC  3971.  From  the  messages  that
> validate, the MN SHOULD choose one with an AT flag in the Handover
> Key Reply Option indicating an authentication algorithm that the
> MN supports. From that message, the MN MUST determine which
> handover key encryption public key to use in the event the MN has
> more than one. The MN finds the right public key to use by
> matching the SEND nonce from the RtSolPr. The MN MUST use the
> matching  private  key  to  decrypt  ...

I think it would be helpful to have a statement where the MN MUST drop
the PrRtAdv if it does not see a nonce from itself.

>        Encrypted Handover Key:
> 
>                      The shared handover key, encrypted with the MN's
>                      handover key encryption public key.
> 

In which format? Can you specify this more explicitly?

Jari

PROTO Write-up

(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?

Vijay Devarapalli is the Document Shepherd for this document. I
have reviewed the document and it is ready for forwarding to the
IESG for publication.

(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 been reviewed by numerous folks, including
folks who are proficient in IP Mobility and Security. This
document went through a WG last call in the MIPSHOP WG. I have no
concerns about the depth or breadth of the reviews that have been
performed.

(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?

None.

(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.

None.

(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 WG consensus in advancing this document.

(1.f) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarize 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.)

No.

(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? If the document
does not already indicate its intended status at the top of
the first page, please indicate the intended status here.

The document meets all the requirements. There were a few minor
nits about additional spacing between words in a few paragraphs.
These nits will be fixed in the next revision of the draft.

(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].

The document splits the references into Normative and Informative
references. This document has a normative dependency on an yet to
be published document - draft-ietf-mipshop-fmipv6-rfc4068bis. But
this draft is also being advanced to the IESG at the same time.

(1.i) Has the Document Shepherd verified that the document's IANA
Considerations 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 the Document
Shepherd conferred with the Responsible Area Director so that
the IESG can appoint the needed Expert during IESG Evaluation?

The IANA considerations section exists and is consistent with
the body of the document. The document requests reservations in
the appropriate IANA registries. No new IANA registries are
created.

(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?

Does not apply.

(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
Relevant content can frequently be found in the abstract
and/or introduction of the document. If not, this may be
an indication that there are deficiencies in the abstract
or introduction.

Fast Mobile IPv6 requires that a Fast Binding Update is secured
using a security association shared between an Access Router and a
Mobile Node in order to avoid certain attacks. In this document, a
method for provisioning a shared key from the Access Router to the
Mobile Node is defined to protect this signaling. The key exchange
messages are required to have SEND security; that is, the source
address is a CGA and the messages are signed using the CGA private
key of the sending node.

Working Group Summary
Was there anything in the WG process that is worth noting?
For example, was there controversy about particular points
or were there decisions where the consensus was
particularly rough?

None.

Document Quality
Are there existing implementations of the protocol? Have a
significant number of vendors indicated their plan to
implement the specification? Are there any reviewers that
merit special mention as having done a thorough review,
e.g., one that resulted in important changes or a
conclusion that the document had no substantive issues? If
there was a MIB Doctor, Media Type, or other Expert Review,
what was its course (briefly)? In the case of a Media Type
Review, on what date was the request posted?

There are no known implementations of the proposed protocol. The
quality of the document is good.

Personnel
Who is the Document Shepherd for this document? Who is the
Responsible Area Director? If the document requires IANA
experts(s), insert 'The IANA Expert(s) for the registries
in this document are .'

Document shepherd: Vijay Devarapalli
Responsible AD: Jari Arkko/Mark Townsley

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