The Internet 2 deployment introduces new capabilities, such as multi-party collaboration, high-scale multimedia assembly and multicast communication. For this reason, the research concerning security is facing new challenges. One such challenge is to create secure multi-session frameworks to ensure the confidentiality of exchanged information. In a multi-session environment, several users are joined at two or more work sessions simultaneously. The confidentiality in these environments can be achieved using cryptographic methods. Unfortunately, the key management, necessary for such environments, creates two main problems: a high complexity in key distribution and a high storage cost. In this paper, we propose an efficient multi-session key management mechanism for dynamic multimedia group communication. Our solution proposes a functional architecture that exploits the overlapping of the user sessions to reduce the redundancy in key distribution. The proposed key management makes use of two key generation strategies: a key derivation technique to reduce the rekey overhead and a pseudorandom number generator that allows the users to generate an independent key per cipher packet.