MPhil Thesis Defence


"SOT : Secure Overlay Tree for Application Layer Multicast"

By

Mr. Wai-Pun Yiu


Abstract

Application layer multicast (ALM) has been proposed to overcome current
limitations in IP multicast. We address, for the first time, offering data
confidentiality in ALM. To achieve confidentiality, a node may need to
continuously re-encrypt packets before forwarding them downstream.
Furthermore, keys have to be changed whenever there is a membership
change, leading to re-key processing overhead at the nodes. For a large
and dynamic group, these re-encryption and re-keying operations incur high
processing overhead at the nodes. We introduce a scalable scheme called
Secure Overlay Tree (SOT) which clusters ALM peers so as to localize
re-keying within a cluster and to limit re-encryption at cluster
boundaries, thereby minimizing the total nodal processing overhead.  We
describe the operations of SOT and compare its nodal processing overhead
with two other basic approaches, namely, host-to-host encryption and whole
group encryption. We present an analytic model for SOT and show that there
exists an optimal cluster size to minimize the total nodal processing
overhead. By comparing with some recently proposed ALM schemes (DT and
NICE), SOT achieves substantial reduction in nodal processing overhead
with little cost in network performance in terms of network stress and
delay.


Date:				Friday, 13 August 2004

Time:				2:00p.m.-4:00p.m.

Venue:				Room 1505
				Lifts 25-26

Committee Members:		Prof. Gary Chan (Supervisor)
				Prof. Shing-Chi Cheung (Chairperson)
				Prof. Lionel Ni


**** ALL are Welcome ****