Speaker: Qingyu Zhang, Ph.D. candidate, Department of Computer Science, UK
Place: Verizon Room, on the 1st floor of the Hardymon Building
Time: Thursday, February 28th, 2:00-3:00pm


This Thursday Qingyu Zhang is going to talk about a key management
mechanism for multicast communication sessions that is based on
'subset-difference' algorithm. The title of this paper is
"Subset-Difference based Key Management for Secure Multicast". This paper
is available at:
http://www.ietf.org/internet-drafts/draft-irtf-smug-subsetdifference-00.txt


				Abstract


   The Subset-Difference algorithm is a new revocation scheme which allows
a Center (such as a Group Controller/ Key Manager) to send a message so
that *every* authorized receiver, but none of the revoked receivers, can
decrypt. This message consists of only 2r keys, where r is the number of
revoked group members. In this draft we first describe this new revocation
scheme, and then then discuss how it can be used for key management in
Secure Multicast applications. Its main advantage is that it eliminates
the need for a mechanism that allows individual updates in case a user did
not receive or did not perform the required re-keing operations. This is
particularly useful in settings with unreliable communication or high
rates of packet loss. It also provides an elegant and efficient solution
for the backward secrecy problem. The algorithm guarantees complete secure
multicast communication even if all revoked users (non group-members)
collude their keys.