Multicasting is a prominent communication mechanism for group oriented applications like video conferencing, interactive group-games and video on demand. IP multicast reduces the bandwidth of the network by sending the source traffic over a multicast tree that contains all members of the group. Due to the lack of security there is a obstructs for the development of multicast in large scale. Typically, the distribution of information with some commercial value or state top-secret data requires the use of appropriate confidentiality mechanisms to prevent non authorized recipients from accessing the content. Indeed, group communication needs to maintain confidentiality so that only valid members of the group could decrypt and access the multicast data even if the data is broadcasted throughout the network. One of the methods to encrypt the secure data is by using a symmetric cryptosystem (AES for instance), where a symmetric key is used to encrypt data at the source side and to decrypt it at receivers side. This key is generally called
Traffic Encryption Key (TEK). The confidentiality requirements for the data shared can be translated into the following different key distribution rules [1]: Group confidentiality: users those were not member of the group should not have right to access to any key that can decrypt any multicast data sent to the group. Forward confidentiality: user who left the group should not have right to access to any future key so that a user cannot decrypt data after he/she leaves the group. Backward confidentiality: a new user who joins the group session should not have right to access to any old keys so that a user cannot decrypt data sent before he/she joins the group. Collusion freedom: any deleted users should not be able to get/deduce the currently using key.