Introduction ......................................................................................................... 132 Background .......................................................................................................... 133

Perfect Forward Secrecy ................................................................................ 134 Strand Spaces .................................................................................................. 136

Framework for Analyzing Partial Forward Secrecy ...................................... 138 Extensions to the Strand Space Model ........................................................ 138 Algorithm for DPFS Computation ............................................................... 139

Analysis of GKA Protocols on Partial Forward Secrecy ................................ 142 Burmester-Desmedt Protocol ....................................................................... 142 Just-Vaudenay Protocol ................................................................................ 143 Becker-Willie Protocol ................................................................................... 143 Steiner-Tsudik-Waidner Protocol ................................................................ 144 Kim-Perrig-Tsudik Protocol......................................................................... 145 Kim Lee-Lee Protocol .................................................................................... 145 Boyd-Nieto Protocol ...................................................................................... 146 A-GDH.2 Protocol .......................................................................................... 146 ID-Based One-Round Authenticated GKA with Bilinear Pairing Protocol ............................................................................................................ 147

Summary of the Analysis of GKA Protocols ................................................... 148 Trust Model .......................................................................................................... 150

Applications Based on P2P Communications ............................................ 152 Cloud-Based Subscribed Journal ............................................................. 152 Interactive Whiteboard ............................................................................. 154 Boardroom Meetings ................................................................................. 154

Trust-Based Analysis of Protocol Suitability to Applications ....................... 155 Burmester-Desmedt Protocol ....................................................................... 156 Just-Vaudenay Protocol ................................................................................ 157 Becker-Willie Protocol ................................................................................... 158 Steiner-Tsudik-Waidner Protocol ................................................................ 158 Kim-Perrig-Tsudik Protocol......................................................................... 159 Kim Lee-Lee Protocol .................................................................................... 159

Group communication is invariably used for services that demand high availability, such as distributed databases, replicated servers and clouds, and collaborative applications, such as multimedia conferencing, shared whiteboards, and multiparty games [1]. Peer-to-peer (P2P) architecture is preferred over hierarchical network architectures in such distributed applications for achieving availability. As data are stored at multiple peers in such architectures, assuring data integrity and condentiality is important [2].