Abstract: Multicast is the basis for many new applications in the internet, and key management is one of the key research areas of multicast security. We particularly analyze the security of the key management scheme based on the one-way function tree(OFT), which is one of the drafts of SMuG, an point out the vulnerabilities in providing forward security and backward security. An improved scheme for providing real forward security and backward security is also proposed.

Key words: one-way function tree, multicast security, key management, forward security, backward security