00000ctm a22000004a 4500 UP-99796217608175395 Buklod 20230503092542.0 m |o d | ta 070926s2005 xx r |||| u|eng d (iLib)UPD-00000528689 DML eng DMLUC LG 995 2005 C65 H6 Ho Hai Van An improvement on logical key hierarchy algorithm for multicast and group security Ho Hai Van. 2005. ix, 81 leaves ill. Thesis (M.S. Computer Science)--University of the Philippines, Diliman. Multicast enables efficient group communication by allowing the sender to transmit a single copy of data, with network elements such as routers and switches making copies as necessary for the receivers. Thus, multicast reduces the computational load at the sender, as well as the number of copies of data on the network. For the successful deployment of group communication applications, multicast security is one of the important problems to solve together with other issues such as traffic management, accounting and biling, and reliability. With respect to security, key distribution is regarded as one of the most difficult challenges so far. The group key should be changed when the membership of the group changes so that departed members cannot decrypt the future group data and new members cannot decrypt the past group data. One fundamental question is how the group key can be efficiently distributed to so many group members when group membership changes in a dynamic fashion. This thesis proposes an improvement on the Logical Key Hierarchy (LKH) algorithm that facilitates efficient distribution of a group key to very large (up to 100,000 members) and dynamic (the period between two membership changes is less than 30 seconds) groups. First, we discuss the LKH algorithm and analyze its overheads such as receiver or key server computation and communication bandwidth. Next, we propose a new variation of the LKH algorithm and evaluate its performance compared to the original LKH. The idea is to reduce LKH overheads by minimizing the height of the logical tree. This is achieved by grouping users into different trees instead of one. Finally, we supplement this analysis by providing a simulation program based on Java Network Simulator (JNS) to demonstrate the advantages of the new algorithm. Multicasting (Computer networks) Security measures. Computer networks Security measures. Data encryption (Computer Science). Multichannel communication. Broadband communication systems. Thesis FI UP UPD DARCHIVES LG 995 2005 C65 H6 UPD DENG-II LG 995 2005 C65 H6 Thesis