You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: A survey of key management for secure group communication 
Chapter Title:  One-way Function Tree 
1. Abstract of Cited Paper (BIB001):  Multicast communication is becoming the basis for a growing number of applications. It is therefore critical to provide sound security mechanisms for multicast communication. Yet, existing security protocols for multicast offer only partial solutions. We first present a taxonomy of multicast scenarios on the Internet and point out relevant security concerns. Next we address two major security problems of multicast communication: source authentication, and key revocation. Maintaining authenticity in multicast protocols is a much more complex problem than for unicast; in particular, known solutions are prohibitively inefficient in many cases. We present a solution that is reasonable for a range of scenarios. This approach can be regarded as a 'midpoint' between traditional message authentication codes and digital signatures. We also present an improved solution to the key revocation problem.

Literature Review:
An improvement in the hierarchical binary tree approach is a one-way function tree (OFT) and was proposed by BIB001 . Their scheme reduces the size of the rekeying message from 2 · (log 2 n) to only (log 2 n). Here a node's KEK is generated rather than just attributed. The KEKs held by a node's children are blinded using a one-way function and then mixed together using a mixing function. The result of this mixing function is the KEK held by the node. This is represented by the following formula: Where left(i) and right(i) denote respectively the left and right children of node i. The function g is one-way, and f is a mixing function: Ancestors of a node are those nodes in the path from its parent node to the root. In this article, the set of ancestor of a node is called ancestor set and the set of siblings of the nodes in ancestor set are called sibling set (see Figure 4) . Each member receives the key (associated to its leaf node), its sibling's blinded key and the blinded keys corresponding to each node in its sibling set. For a balanced tree, each member stores l og 2 n + 1 keys. For example, in Figure 4 , member u 4 knows key k 4 and blinded keys k plying this information to the formula 1, member u 4 is able to generate all keys in its ancestor set (k 34 , k 14 and k). The message size reduction is achieved because in the standard scheme, when a node's key changes, the new key must be encrypted with its two children's keys, and in the OFT scheme, the blinded key changed in a node has to be encrypted only with the key of its sibling node. Figure 5 shows an example of this scheme. Member u 3 joins the group at node n 34 . It requires keys k 34 , k 14 and k to be changed. The only values that must be transmitted are the blinded KEKs k Each is respectively encrypted with k 4 , k 12 and k 58 . The new KEKs can be calculated by every group member: BIB002 proposed a slightly different approach that achieves the same communication overhead. Their scheme uses a pseudo-random-generator  ] to generate the new KEKs rather than a one-way function and it is applied only on users removal. This scheme is known as the one-way function chain tree. The pseudo-random-generator, G(x), doubles the size of its input (x), and there are two functions, L(x) and R(x), that represent the left and right halves of the output of where |L(x)| = |R(x)| = |x|). When a user u leaves the group, the algorithm to rekey the tree goes as follows: