RE: FCIP and iFCP Keying Problem

[Black_David@emc.com]

Resending as I didn't see this come through - apologies
if it's a duplicate.  --David

> -----Original Message-----
> From: Black, David (MKT Hopkinton) 
> Sent: Friday, September 07, 2001 6:28 PM
> To: Black, David (MKT Hopkinton); ips@ece.cmu.edu
> Subject: RE: FCIP and iFCP Keying Problem
> 
> 
> Filling in a couple of missing pieces here:
> 
> - See Section 4.4 of draft-aboba-ips-iscsi-security-00.txt
> 	for more details on the man-in-the-middle vulnerability.
> 	That vulnerability is based on the use of group pre-shared
> 	keys.  
> - My strong language below is based in part on an 
> 	assumption that banning group pre-shared keys is
> 	unworkable in practice.  Key management is a pain,
> 	and use of group pre-shared keys simplifies it, even
> 	though it has some security costs.
> 
> Questioning the latter assumption is reasonable, but I'll
> point out that group pre-shared (vs. per session pre-shared)
> keys are a fact of life in current IPsec deployment/management,
> and even turn up in the absence of dynamic IP address
> assignment.  The reason the text in my previous message
> just said "pre-shared keys" rather than "group pre-shared keys"
> is that there may be no way for a participant in an IKE
> session to know whether the pre-shared key was shared only
> among the two endpoints of the session or with other parties.
> 
> Thanks,
> --David
> 
> > -----Original Message-----
> > From: Black_David@emc.com [mailto:Black_David@emc.com]
> > Sent: Friday, September 07, 2001 4:34 PM
> > To: ips@ece.cmu.edu
> > Subject: FCIP and iFCP Keying Problem
> > Importance: High
> > 
> > 
> > Both FCIP and iFCP intend to require:
> > 
> > 	- IKE with pre-shared keys MUST implement
> > 	- IKE with public-key based keys MAY implement
> > 	- IKE Main Mode MUST implement
> > 	- IKE Aggressive Mode MAY implement
> > 
> > That's not acceptable because the result of combining
> > the two mandatory (MUST) mechanisms is vulnerable to a
> > man-in-the-middle attack.
> > 
> > If IKE with pre-shared keys is "MUST implement" (which
> > makes sense, as it's the simplest IKE authentication
> > mechanism), then:
> > 	- IKE Aggressive Mode needs to be "MUST implement"
> > 	- Use of IKE Main Mode with pre-shared keys needs
> > 		to be "SHOULD NOT use" or "MUST NOT use".
> > Alternatively, if IKE Aggressive Mode remains "MAY implement",
> > then:
> > 	- IKE with signature authentication based on public
> > 		keys needs to be "MUST implement" along with
> > 		some certificate usage guidelines.
> > 	- Pre-Shared keys needs to be "MAY implement" (can't
> > 		be any stronger than the requirement for
> > 		IKE Aggressive Mode).
> > 	- Use of IKE Main Mode with pre-shared keys needs
> > 		to be "SHOULD not use" or "MUST not use".
> > 
> > Changing IKE to remove the Main Mode vulnerability
> > with pre-shared keys is not a viable approach.
> > 
> > Sorry,
> > --David
> > 
> > ---------------------------------------------------
> > David L. Black, Senior Technologist
> > EMC Corporation, 42 South St., Hopkinton, MA  01748
> > +1 (508) 435-1000 x75140     FAX: +1 (508) 497-8500
> > black_david@emc.com       Mobile: +1 (978) 394-7754
> > ---------------------------------------------------
> > 
>