Key agreement is a critical part of providing security services for group communication systems.
Most of the current contributory key agreement protocols are not designed to tolerate failures and membership changes during execution. Perrig et al. Rep. CNDS 2000-4, Department of Computer Science, Johns Hopkins University, 2000. Y. Amir, Y. Kim, C. Nita-Rotaru, J. Schultz, J. Stanton, and G. Tsudik, Exploring robustness in group key agreement, Tech. Rep. CNDS 2000-4, Department of Computer Science, Johns Hopkins University, 2000.