Collusion resistant self-healing key distribution in mobile wireless   networks
  A fundamental concern of any secure group communication system is key management and wireless environments create new challenges. One core requirement in these emerging networks is self-healing. In systems where users can be offline and miss updates, self-healing allows a user to recover lost session keys and get back into the secure communication without putting extra burden on the group manager. Clearly, self-healing must only be available to authorized users. This paper fixes the problem of collusion attack in an existing self-healing key distribution scheme and provides a highly efficient scheme as compared to the existing works. It is computationally secure, resists collusion attacks made between newly joined users and revoked users and achieves forward and backward secrecy. Our security analysis is in an appropriate security model. Unlike the existing constructions, our scheme does not forbid revoked users from rejoining in later sessions. 
Ratna Dutta, Sugata Sanyal
cs.NI