Subject: RE: Working Group Last Call: draft-ietf-smime-small-subgroup-02.t xt

From: "John C. Kennedy" <[email-masked]>
Date: Wed, 1 Dec 1999 14:20:42 -0800

RE: Working Group Last Call: draft-ietf-smime-small-subgroup-02.t
xtRobert,

My concerns about alignment and attribution with the X9.42 draft stated
recently on the mailing list are applicable here.  I suggest replacing
[x942] with [RFC2631], or something similar. RFC 2631 is currently, and
presumably will remain, the normative reference; not the ANSI draft.  Even
if X9.42 ever becomes a standard, RFC2631 will continue to profile or
otherwise approximate it but still remain the normative reference.

-John

---

From: "Linn, John" <[email-masked]>
Date: Thu, 2 Dec 1999 11:17:33 -0500

Robert,

Thanks for your quick and thoughful consideration of the comments.  Your
responses look good; we've a residual content-level observation to make on
only one item:

[Sec. 4] 

Re: "This isn't clear to me. For example, if an attacker modified both
public keys to be yb=ya=1 and the parties authenticated each other over a
telephone conversation in which they read out the agreed upon key. Now, they
will both agree on the same key and they will have a certain level of
authentication, but the attacker will be able to eavesdrop. Thus, it is
important that each party's *public key* be authenticated, which is the
point I was trying to make with this section. However, I agree that the way
things are presently worded may be misleading. I will change the first
sentence of the second paragraph to "In some ephemeral-ephemeral key
agreements protection may be required for both entities." "

Good points. As you observe, E-E gives an attacker more flexibility since
both parties' public keys can be changed and they can be coerced into
computing the same key from a small space. In E-S, only the sender's public
key can be changed, and only the recipient can be coerced by an outsider
attacker into computing a key from a small space.  While this may be
apparent, it seems useful to state explicitly for purposes of clarifying
comparison. 

[Sec. 3, minor editorial]

Re: How about if I add a sentence following the first paragraph of Section 3
stating "Implementer's should note that some of the procedures described in
this section may be the subject of patents or pending patents."

"Implementer's" -> "Implementers".

--jl

---

From: Robert Zuccherato <[email-masked]>
Date: Thu, 2 Dec 1999 14:17:37 -0500

John;

I will add your comment below as the second paragraph of Section 4.  You are
correct, it does clarify the discussion.

	Robert.

> ----------
> From: 	Linn, John[SMTP:[email-masked]]
> Sent: 	Thursday, December 02, 1999 11:17 AM
> To: 	'Robert Zuccherato'; [email-masked]
> Cc: 	'Burt Kaliski'
> Subject: 	RE: Working Group Last Call:
> draft-ietf-smime-small-subgroup-02.t xt
> 
> Robert,
>