Re: [cicm] comments on CICM

http://tools.ietf.org/html/rfc4869 lists AES-GCM as part of Suite B.

-----Original Message-----
From: cicm-bounces@ietf.org [mailto:cicm-bounces@ietf.org] On Behalf Of Cottrell Jr., James R.
Sent: Wednesday, August 03, 2011 7:49 AM
To: CICM Discussion List
Subject: Re: [cicm] comments on CICM

David McGrew,

In your email you stated " Considering that AES-GCM is required for Suite B, and the Suite B RFCs
all cite RFC 5116, the lack of AEAD support appears problematic"

Can you please provide an authoritative document stating this requirement?

Thanks,

Jim Cottrell

-----Original Message-----
From: cicm-bounces@ietf.org [mailto:cicm-bounces@ietf.org] On Behalf Of Novikov, Lev
Sent: Wednesday, August 03, 2011 10:03 AM
To: CICM Discussion List (cicm@ietf.org)
Subject: [cicm] FW: comments on CICM

FYI: Below is an insightful email from David McGrew that does not
appear to have made it to the mailing list nor was it held for
moderation so the list never saw it.

Lev

-----Original Message-----
From: David A. McGrew [mailto:david.a.mcgrew@mindspring.com]
Sent: Wednesday, July 27, 2011 14:39
To: cicm@ietf.org; Lanz, Dan; Novikov, Lev
Subject: comments on CICM

Hi Lev and Daniel,

I skimmed the CICM documents and have several comments.

It seems that the major goal for CICM is multi-vendor support.
Worthwhile goal, but what crypto hardware vendors whose products
support IETF standards are participating in this effort?

RFC 5116 defines a standard interface to Authenticated Encryption with
Associated Data (AEAD) algorithms, which is used by TLS 1.2, SSH,
SRTP, IKE, and SMIME, and is backwards compatible with ESP.   The AEAD
interface is simple (two defined messages, four inputs and one output
each), and AEAD is widely regarded as the state of the art in security
and efficiency (including both OCB and GCM, for instance).  It appears
that CICM is not compatible with this interface, in which case it
would be a real step backwards.  (If CICM does support AEAD, it is not
clear to me how it does.  Am I missing something?)

CICM is intended for use in a high assurance crypto module.
Considering that AES-GCM is required for Suite B, and the Suite B RFCs
all cite RFC 5116, the lack of AEAD support appears problematic.

The use cases for which CICM is intended are those where
"cryptographic transformation of data initiated in one security
domain with the result made available in another security domain";
three cases are given, two of which are HAIPE.  So clearly the CICM
design has been driven by high assurance requirements that are highly
security conscious and not publicly available.   My question here is:
how will the CICM design make implementations of IETF security
protocols better?   If CICM is tightly bound to non-public protocols,
it will not have much relevance to the IETF.   On the other hand, if
there is a document that shows how a high assurance design approach
can be used in an IETF standard like TLS or IPsec, that could be
valuable.   It could be a good contribution to the IETF to provide
implementation criteria or design approaches that are applicable to
internet standards.  I think there would be a good amount of interest
in this sort of work, and in fact I would be very happy to see that
sort of document show up in IRTF CFRG.

An important nit: MD5 is used as an example on pg 24 of draft-lanz-
cicm-02.  It has been deprecated by RFC 6151; I encourage that a
different hash be used as an example.

regards,

David

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