A scalable scheme for multilevel packet authentication in secure multicasting

Since communication has become an integral part of modernlife, security and authentication have also become important issues for providing secure communication. The issue of providing communication among a group of users has also been in the forefront, and multicasting has become a key technology for supporting such communication. This thesis explores new methods for multicast authentication. First, the thesis discusses several multicast authentication schemes: (i) public-key systems and Message Authentication Codes (MACs), and their relation to multicast authentication, and (ii) different views of multicast authentication, including digital streams, off-line computation, and using less secure but more efficient authentication algorithms. Then, the thesis proposes a scheme for multicast authentication based on a digital streams scheme, extended Fiege-Fiat-Shamir (eFFS), which is efficient and scalable. eFFS allows multiple levels of authentication, but sending these multiple levels may consume a lot of bandwidth. This research enhances eFFS (the enhanced scheme is called Modified eFFS, or MeFFS) by partitioning the receivers of a group to form several multicast subgroups, and sending different authentication levels to different subgroups. The performance enhancement of MeFFS, in terms of bandwidth savings, is quantified through simulation studies. Our studies show that MeFFS outperforms eFFS for multicast groups where the trees corresponding to the subgroups are highly disjoint. Finally, some suggestions are made to make the scheme more scalable and deployable