Subject: Working Group Last Call: draft-ietf-smime-small-subgroup-02.txt

From: Russ Housley <[email-masked]>
Date: Tue, 16 Nov 1999 20:18:17 -0500

Announcing S/MIME Working Group Last Call.

	Title		: Methods for Avoiding the "Small-Subgroup" Attacks on
			: the Diffie-Hellman Key Agreement Method for S/MIME
	Author		: R. Zuccherato
	Filename	: draft-ietf-smime-small-subgroup-02.txt
	Date		: November 1999
	
In some circumstances the use of the Diffie-Hellman key agreement scheme
in a prime order subgroup of a large prime p is vulnerable to certain
attacks known as "small-subgroup" attacks.  Methods exist, however, to
prevent these attacks.  This document will describe the situations
relevant to implementations of S/MIME version 3 in which protection is
required and the methods that can be used to prevent these attacks.

This document will become an Informational RFC.

Working Group Last Call will close on 30 November.

S/MIME WG Chair,
    Russ

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From: Russ Housley <[email-masked]>
Date: Tue, 16 Nov 1999 20:35:18 -0500

I have a few comments on draft-ietf-smime-small-subgroup-02.txt.

1.  Section 1.2, 3rd paragraph: Please explain "r<<q".  This is the only 
use of the "<<" symbol.

2.  Section 2.2, 2nd paragraph: Please explain that any protocol event that 
allows the attacker to conclude that decryption was successful is also 
relevant.  Such events include replies and returning signed receipts.

3.  Section 2.2, 3rd paragraph: Please remove the extra space after "party".

4.  Section 4, 4th paragraph: Any integrity protection for the public keys 
(not just signatures), will thwart the attack.  Please expand the text to 
cover any integrity mechanism.

5.  Section 7:  Please update the [CMS], [MSG], and [x942] references to 
point to the RFCs.