[Hipsec] OPS-DIE review of draft-ietf-hip-over-hip-05

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I have performed an Operations Directorate review of draft-ietf-hip-over-hip-05

Operations directorate reviews are solicited primarily to help the area directors improve their efficiency, particularly when preparing for IESG telechats, and allowing them to focus on documents requiring their attention and spend less time on the trouble-free ones.  Improving the documents is important, but clearly a secondary purpose.  A third purpose is to broaden the OpsDir reviewers' exposure to work going on in other parts of the IETF.

Reviews from OpsDir members do not in and of themselves cause the IESG to raise issue with a document. The reviews may, however, convince individual IESG members to raise concern over a particular document requiring further discussion. The reviews, particularly those conducted in last call and earlier, may also help the document editors improve their documents.

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Summary: This draft is basically ready for publication, but has nits that should be fixed before publication.

HIP is in a related functional space to IPsec, and in both cases IETF protocols are not typical means for operation and management (e.g., the IPsec SPD MIB is not widely used for configuring IPsec).  This draft specifies minor extensions to HIP in that it defines two additional HIP transports, so it's not a reasonable vehicle for a general discussion of HIP operations and management.  As a result, this review focuses on operational characteristics of the extensions specified in the draft.

This draft defines two new fully encrypted transports for HIP signaling messages - ESP and ESP over TCP.  The draft includes details on negotiation of these modes as extensions to existing HIP signaling, providing support for incremental deployment, a migration path and backwards compatibility.  While it is probably best to start out with the intended transport (i.e., negotiate it in the HIP base exchange), means are also specified to negotiate a transport change later.  An error report is defined for use when a HIP node policy requires use of one of these fully encrypted transports, but none is offered in negotiation.  Fallback to a non-encrypted transport is specified and recommended (SHOULD) when the encrypted transport fails.

I have one recommendation for change - this draft is somewhat inconsistent about support for a HIP node policy that requires use of an encrypted transport for HIP signaling.  Section 3.3 provides an essential building block, the error signaling mechanism to indicate that an encrypted transport is required and none was proposed.  On the other hand, Section 5 is unclear with respect to this class of policy in that it strongly recommends (SHOULD) fallback to a non-encrypted HIP connection but requires (MUST) that "messages that are intended to be sent only encrypted" not be sent unencrypted.  If the "messages that are intended to be sent only encrypted" are all HIP messages after the base exchange, these two requirements appear to be in conflict.

I suggest adding a short explanation to Section 5 of what would be reasonable vs. unreasonable policy for "messages that are intended to be sent only encrypted", and how to use the Section 3.3 error report when a failed encrypted connection is recovered by attempting to fall back to an unencrypted connection when HIP node policy requires encryption of all signaling after the base exchange.

Thanks,
--David
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David L. Black, Distinguished Engineer
EMC Corporation, 176 South St., Hopkinton, MA  01748
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