Re: [IPsec] I-D Action: draft-ietf-ipsecme-rfc4307bis-00.txt

[Tero Kivinen <[e-mail]>]

John Mattsson writes:
> - BTW, What does it mean that an algorithm like ENCR_RC5 is not
> listed, does that mean “MAY”, “MUST NOT”, or “totally unspecified”?

It means this document does not specify whether they should be used or
not, i.e. MAY.

> - Section 3.2. says “When an AEAD algorithm (see Section 3.1) is
> used, no algorithm from this table needs to be used.” Shouldn’t this
> be “MUST NOT be used”.

This document just states the fact, the actual MUST NOT is in the
RFC5282, and I do not think we should repeat that here. I.e. this text
just states the fact of life based on the RFC5282, but does not make
any requirements. 

> - Section 3.1. I think AES_CCM_8 should somehow be restricted to
> IoT, as using 64 bit tags in IKE does not sound like general good
> advise. Also IoT implementations would probably just implement
> “ENCR_AES_CCM_8”, “PRF_HMAC_SHA2_256", and "256-bit random ECP
> group" and skip everything else. It seem to make more sense to
> specify an IoT profile in a separate section.

The IoT devices talk to each other, but also to more general purpose
servers, i.e., in your home you might have some kind home area network
server, where all the IoT devices connect to. In that case those
bigger boxes do want to implement the same AES_CCM_8 just so that
those IoT devices which didn't implement anything else can talk to
them.

I.e. I think it is good thing to require real systems to have SHOULD
for the AES_CCM_8. Of couse if your implementation is never expected
to talk to IoT devices, then that is good reason to go against the
SHOULD and leave the AES_CCM_8 implementation out.

> - Section 3.4. The Diffie-Hellman group table diverges heavily from
> the rest with only 112-bit security as MUST, and no group offering
> 128-bit security as even SHOULD+.

That depends how you calculate the securities of the Diffie-Hellman
groups. If you check RFC3526 that gives two strengh estimates for
2014-bit group, 110 and 160 bits. The 160 bit strength takes also
account the memory prices in the calculations, the 110 assumes memory
is free, and CPU cost is only thing that matters. 

> This may be ok, but I think the ipsecme group should try to fulfill
> general recommendations on security levels (NIST, ECRYPT) and have a
> plan on how to make 2048-bit MOPD a MUST NOT before 2030.

I think we are going to replace this document several times before
2030. We actually should have replaced this already few years ago, so
this update is already bit late, but I would assume we might make new
version after we get those new EC groups now being defined to the
implementations. On the other hand there are lots of people still
running IKEv1, so getting them to implementations might get time.

> Not being able to forbid 1024-bit MOPD is this draft is a failure,
> let’s not repeat it.

We should move it to MUST NOT in next update, and then we can also
revisit the discussion of 2048-bit MODP group. 
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