1. Rating Technical quality 5: Contents are completely correct. There are no errors. 4: Contents are mostly correct. Some improvements suggested below. 3: Some errors which can be easily corrected, as described below. 2: Several errors but most are minor errors 1: Several/major errors 5 Originality 5: New results of publishable quality and good analysis of current state 4: Contains some new ideas, but can be developed as described below; good analysis of current state 3: No significantly new ideas, but good analysis of current state 2: Good survey of current state; no new ideas 1: Survey of current state has gaps 4 Editorial quality 5: Clear, understandable and easy to read 4: Mostly understandable, some improvements identified below 3: Understandable with some effort, several improvements suggested below 2: Hard to understand; several improvements suggested below 1: Very hard to understand 4 Overall grade (overall, how do you rate this paper?) 5: Excellent 4: Very good 3: Good 2: Satisfactory 1: Poor 5 Confidence (how confident are you about this review?) 3: I have good or expert level knowledge of this topic 2: I have some general knowledge of this subject 1: This is a completely new subject to me; I made educated guesses 2 2. Detailed comments 2a. Technical quality The paper describes the current work on IP multicast key management, states the problems of these approaches and suggests the use of Host Identity Protocol to enhance the current methods. I think the paper is a good survey of the state of the art. From the paper it can be seen that the author has good knowledge of the subject. He points out clearly the reasons and development of the IP multicast and extends the discussion to the IP multicast key management. Even readers who are not so familiar with IP multicast can understand the paper because it is logical and tells enough background information. While introducing the HIP, there could be a short description of the HIP service registration protocol. After all, it plays a key role in HIP multicast extension. Also there could be a short discussion of HIP protocol's deployment. What changes it requires for current networks and network elements? How hard it would be to adapt the current multicast key exchange protocols to HIP. Are there other approaches to enhance the IP multicast than HIP? If there are, you could add these to the Related Work chapter. 2b. Originality The paper suggests the usage of HIP for IP multicast key management. HIP renews the TCP/IP architecture and provides many novel features that can be utilized for instance in multicast. I think that it is well justified to use HIP to enhance the IP multicast key management. 2c. Editorial quality Language of the paper is very good and easy to understand. However, you use lots of abbreviations that are hard to remember. I suggest that you open the abbreviation every now and then to help the reader to remember the key terms. Abstract states very clearly the content of the paper. Introduction motivates the reader well and describes the problems that are discussed in the paper. There are lots of different things discussed in the paper. Perhaps Introduction could contain a few lines about how the paper is organized. I suggest that you rename either chapter 3 or 3.2. Currently these two chapters have the same title and it is a little bit confusing. What is SKEYID_a in chapter 6? Pictures are good and make the protocols easier to understand. A minor style issue: doesn't -> does not (4.2,5) I found only couple typos: 3.1 Logical Key Hiearchy -> Hierarchy 3.2.2 Whe public key or...-> When public... 3.2.3 The ISAKMP phase 1 negotiation (e.g. IKE[]) -> something missing between brackets 4.1 host identity (HI) -> host identifier ... 4.2 The puzzle is create so that at the verifciation -> ...verification