Subject: [secdir] Review of draft-ietf-pce-path-03

From: "Hilarie Orman" <[email-masked]>
Date: Tue, 14 Oct 2008 12:52:47 -0600

Preserving Topology Confidentiality in Inter-Domain Path Computation
Using a Key-Based Mechanism, draft-ietf-pce-path-key-03.txt

Do not be alarmed.  I have reviewed this document as part of the
security directorate's ongoing effort to review all IETF documents
being processed by the IESG.  These comments were written primarily
for the benefit of the security area directors. Document editors and
WG chairs should treat these comments just like any other review
comments.

Based on the title, I thought this was about cryptographic keys, but
it isn't.  Even the commendably well-written abstract (all acronyms
expanded!) did not disabuse me of this belief.  If path keys were
instead called, for example, opaque path identifiers, the draft would
benefit.

The confidentiality issue boils down to saying that in messages that
necessarily pass from a trusted domain, across untrusted domains, and
into a trusted domain, there is a protocol element that is, in some
circumstances, confidential, so an exisiting mechanism can be used to
carry an opaque identifier instead of the actual element.  The mapping
from the opaque identifier to the actual element is carried in
protocol messages that "can be authenticated and made secure" as
described in other documents.  "Made secure" presumably encompasses
confidentiality and integrity.

Assuming that everyone knows how to configure their authentication and
cryptographic keys with trusted parties correctly, the overall idea
seems sound.

An risk not mentioned in the security section is the possibility of
infering the mapping if the opaque identifiers are not chosen
randomly.  Observers, over time, might be able to make such inferences
based on being able to predict the identifiers and the network
topology changes.

Hilarie
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