In this paper, we present collusion attacks on a very recently proposed group re-keying scheme, the Secret Keys Multiplication (SKM). Users can conspire together (collude) to obtain the private key of the trusted group controller server. This is a very serious weakness in the SKM and shows that it is not secure at all. It should therefore not be used, but should go through a major redesign.
The Advancement of ICT for a Secure Global Information Society : MMU International Symposium on Information and Communication Technologies/M2USIC 2003, Petaling Jaya, Malaysia, 2-3 October 2003,