Subject: Re: Moving forward with IKE V2: A proposal for final edits to ikev2-04

From: [email-masked]
Date: Sat, 1 Feb 2003 21:58:53 -0500

Stephen Kent <[email-masked]> wrote on 01/31/2003 06:31:45 PM:
> It is likely that IANA will add additional Suite-IDs in the future, and
> some users may want to use private suites, especially for IKE where
> implementations should be capable of supporting different parameters,
> up to certain size limits. In support of this goal, all
> implementations of IKEv2 SHOULD [I'd prefer MUST, but Paul has argued
> eloquently for very restrictive criteria for MUST re suites.] include
> a management facility that allows specification (by a user or system
> administrator) of Diffie-Hellman parameters (the generator, modulus,
> and exponent lengths and values) for new IKE Suites. Implementations
> SHOULD provide a management interface via which these parameters and
> the associated Suite-IDs may be entered (by a user or system
> administrator), to enable negotiating such Suites.

I would strongly oppose making this a "MUST" and have mixed feelings
about "SHOULD". If we are going to include it, I think we have to say
what the size limits are, and whether all intermediate sizes SHOULD
be supported. We had such a debate over RSA key sizes, without
concrete resolution. The current draft says 1024 and 2048 bit keys
MUST be supported and doesn't say anything about SHOULD. There
exist implementations of crypto toolkits that don't support RSA
keys that are not an integer multiple of 16 bits in size. Very
general requirements make conformance testing harder.

          --Charlie

Opinions expressed may not even be mine by the time you read them, and
certainly don't reflect those of any other entity (legal or otherwise).

---

From: Stephen Kent <[email-masked]>
Date: Mon, 3 Feb 2003 13:24:06 -0500

>general requirements make conformance testing harder.

Charlie,

My goal in pushing for this is NOT to require any implementation to 
support a bigger key size, but rather to allow specification of 
parameters within whatever constraints we established separately for 
parameters sizes.  I'm very much open to rewording suggestions to 
avoid any confusion over this aspect of my proposed text.

Steve