[AG-TECH] AG Security

[Bill Nickless]

Hi Markus--

Some first reactions to your comments.

I'm not convinced of the viability of a security/encryption model that 
operates below the application layer.

You mention the possibility of an attacker joining the group "and running 
crack over it".  Quoting Rescorla(?) at the IETF IESG Plenary in Yokohama 
last week, "the Internet is where you hand your packets off to your 
attacker to deliver for you."  In other words, the possibility of the 
attacker getting your traffic is assumed even in the case of 
unicast.  Granted, multicast traffic is easier to get hold of than by 
compromising an intermediate router to send you unicast traffic.  But the 
assumptions should be the same--your attacker has all your traffic.

That being said, you might like to look over some of the IETF MAGMA Working 
Group discussions on secure IGMP.  The attack model here is slightly 
different; it appeared to be focused to help a service provider secure 
multicast media content.  That is, the service provider would supply (say) 
HBO on a certain multicast group address, and only those subscribers to HBO 
would be able to join that multicast group.

Deb Agarwal of LBNL presented some work at the last Access Grid retreat on 
securing multicast groups and sessions.  She pointed to 
http://www-itg.lbl.gov/CIF/GroupComm/ in her presentation, which is 
available at 
http://www-fp.mcs.anl.gov/fl/accessgrid/ag-retreat-2002/proceedings/agarwal.pdf 
.



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Bill Nickless    http://www.mcs.anl.gov/people/nickless      +1 630 252 7390
PGP:0E 0F 16 80 C5 B1 69 52 E1 44 1A A5 0E 1B 74 F7     nickless at mcs.anl.gov