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Autonomous vehicles offer various advantages to both vehicle owners and automobile companies. However, despite the advantages, there are various risks associated with these vehicles. These vehicles interact with each other by forming a vehicular network, also known as VANET, in a centralized manner. This centralized network is vulnerable to cyber-attacks which can cause data loss, resulting in road accidents. Thus, to prevent the vehicular network from being attacked and to prevent the privacy of the data, key management is used. However, key management alone over a centralized network is not effective in ensuring data integrity in a vehicular network. To resolve this issue, various studies have introduced a blockchain-based approach and enabled key management over a decentralized network. This technique is also found effective in ensuring the privacy of all the stakeholders involved in a vehicular network. Furthermore, a blockchain-based key management system can also help in storing a large amount of data over a distributed network, which can encourage a faster exchange of information between vehicles in a network. However, there are certain limitations of blockchain technology that may affect the efficient working of autonomous vehicles. Most of the existing blockchain-based systems are implemented over Ethereum or Bitcoin. The transaction-processing capability of these blockchains is in the range of 5 to 20 transactions per second, whereas hashgraphs are capable of processing thousands of transactions per second as the data are processed exponentially. Furthermore, a hashgraph prevents the user from altering the order of the transactions being processed, and they do not need high computational powers to operate, which may help in reducing the overall cost of the system. Due to the advantages offered by a hashgraph, an advanced key management framework based on a hashgraph for secure communication between the vehicles is suggested in this paper. The framework is developed using the concept of Leaving of Vehicles based on a Logical Key Hierarchy (LKH) and Batch Rekeying. The system is tested and compared with other closely related systems on the basis of the transaction compilation time and change in traffic rates. [ABSTRACT FROM AUTHOR]

Summary: Space key management schemes play a critical role in space information network security services. However, the existing space key management schemes are inefficient. To overcome these problems, this paper proposed a cluster group key management scheme, in which the space nodes are divided into different clusters. The ground control center (GCC) is used as a private key generation center. The threshold technique based on low‐density parity‐check code (LDPC) is used in the group key management of the cluster‐heads. The key escrow is transferred to GCC, which is a compromise of efficiency and security. The logical key hierarchy is used to manage the group key of the cluster. Furthermore, the bilinear paring‐based cryptosystem is employed to provide the identification. The formalized security proof of the protocol using the Extended Canetti–Krawczyk (ECK) model is introduced to prove the authentication and security. The consistency, forward secrecy, backward secrecy, ability to against the collusion attack and performance are analyzed and simulated. The result shows that the proposed scheme takes lower storage cost and computational cost. [ABSTRACT FROM AUTHOR]

Bir yayın haberleşme yönteminde bir kaynaktan çoklu kullanıcılara mesaj iletimi için genellikle içerisinde şifreleme yöntemlerinin kullanıldığı şemalardan yararlanılır. Bu şema yapıları anahtar sunucu işlemleri açısından merkezi ve de-merkezi olmak üzere ikiye ayrılır. Bu çalışmada günümüzde yaygın olarak kullanılan iki merkezi yöntem olan Mantıksal Anahtar Hiyerarşisi (MAH) ve Tek Yönlü Fonksiyon Ağacı (TFA) şemalarına değinilmiştir. Yayın haberleşme için bir şema önerilmiş ve kullanıcı ekleme/çıkarma işlemlerinde anahtar iletim sayıları-boyutları ve kullanıcılarda bulunan anahtar sayıları-boyutları açılarından mevcut şemalar ile karşılaştırılmıştır.

Autonomous vehicles offer various advantages to both vehicle owners and automobile companies. However, despite the advantages, there are various risks associated with these vehicles. These vehicles interact with each other by forming a vehicular network, also known as VANET, in a centralized manner. This centralized network is vulnerable to cyber-attacks which can cause data loss, resulting in road accidents. Thus, to prevent the vehicular network from being attacked and to prevent the privacy of the data, key management is used. However, key management alone over a centralized network is not effective in ensuring data integrity in a vehicular network. To resolve this issue, various studies have introduced a blockchain-based approach and enabled key management over a decentralized network. This technique is also found effective in ensuring the privacy of all the stakeholders involved in a vehicular network. Furthermore, a blockchain-based key management system can also help in storing a large amount of data over a distributed network, which can encourage a faster exchange of information between vehicles in a network. However, there are certain limitations of blockchain technology that may affect the efficient working of autonomous vehicles. Most of the existing blockchain-based systems are implemented over Ethereum or Bitcoin. The transaction-processing capability of these blockchains is in the range of 5 to 20 transactions per second, whereas hashgraphs are capable of processing thousands of transactions per second as the data are processed exponentially. Furthermore, a hashgraph prevents the user from altering the order of the transactions being processed, and they do not need high computational powers to operate, which may help in reducing the overall cost of the system. Due to the advantages offered by a hashgraph, an advanced key management framework based on a hashgraph for secure communication between the vehicles is suggested in this paper. The framework is developed using the concept of Leaving of Vehicles based on a Logical Key Hierarchy (LKH) and Batch Rekeying. The system is tested and compared with other closely related systems on the basis of the transaction compilation time and change in traffic rates.

Multicasting may be a productive secure group communication components in UAV (Unmanned autonomous vehicles) - MBN (Mobile ad hoc networks) to distribute group key to a variety of recipients. During this paper, we have a tendency to propose a secure information group action and economical delivery of group key management theme, hybrid group key management (HGKM), for multicasting. This approach, contrasted with the Logical Key Hierarchy (LKH), Group Key Management Protocol (GKMP), and One-Way Function Tree (OFT) in multicast group key management approaches, we can improve the operation efficiency of wireless network Environment. [ABSTRACT FROM AUTHOR]

Multicasting may be a productive secure group communication components in UAV (Unmanned autonomous vehicles) – MBN (Mobile ad hoc networks) to distribute group key to a variety of recipients. During this paper, we have a tendency to propose a secure information group action and economical delivery of group key management theme, hybrid group key management (HGKM), for multicasting. This approach, contrasted with the Logical Key Hierarchy (LKH), Group Key Management Protocol (GKMP), and One-Way Function Tree (OFT) in multicast group key management approaches, we can improve the operation efficiency of wireless network Environment.

With the development of 5G and the Internet of Things (IoT), mobile terminals are widely used in various applications under multicast scenarios. However, due to the limited computation resources of mobile terminals, reducing the computation cost of members in group key distribution processes of dynamic groups has become an important issue. In this paper, we propose a computation-efficient group key distribution (CEGKD) protocol. First, an improved secret sharing scheme is proposed to construct faster encryption and decryption algorithms. Second, the tree structure of logical key hierarchy (LKH) is employed to implement a simple and effective key-numbering method. Theoretical analysis is given to prove that the proposed protocol meets forward security and backward security. In addition, the experiment results show that the computation cost of CEGKD on the member side is reduced by more than 85% compared with that of the LKH scheme.

Group key management (GKM) in mobile communication is important to enable access control for a group of users. A major issue in GKM is how to minimize the communication cost for group rekeying. To design the optimal GKM, researchers have assumed that all group members have the same leaving probabilities and that the tree is balanced and complete to simplify analysis. In the real mobile computing environment, however, these assumptions are impractical and may lead to a large gap between the impractical analysis and the measurement in real-life situations, thus allowing for GKM schemes to incorporate only a specific number of users. In this paper, we propose a new GKM framework supporting more general cases that do not require these assumptions. Our framework consists of two algorithms: one for initial construction of a basic key-tree and another for optimizing the key-tree after membership changes. The first algorithm enables the framework to generate an optimal key-tree that reflects the characteristics of users’ leaving probabilities, and the second algorithm allows continual maintenance of communication with less overhead in group rekeying. Through simulations, we show that our GKM framework outperforms the previous one which is known to be the best balanced and complete structure. [ABSTRACT FROM AUTHOR]

Abstract: Secure multicast applications of multimedia contents, such as Internet TV, pay per view, satellite TV, etc., need to maintain a high number of keys. In these applications, a user contracts a group of channels or even specific content (films, sports, etc.) which do not have to coincide with the services contracted by other users, so different keys are needed to encrypt the contents. These keys must be recalculated, encrypted and redistributed when a user joins or unjoins a specific group in order to prevent users who do not belong to a group from being able to access the contents. Original algorithms generate only one group key for all users, so this key must be recalculated and resent when a user joins or unjoins in the user group. This is an important problem, because a group key could be changed even when one content is performing. This paper presents a high performance implementation of one of the most employed algorithms of group key maintenance, the LKH algorithm, using reconfigurable hardware and a very high and realistic number of users (8,388,609). The performance obtained by this study improves a lot other results found in the literature in terms of both performance and number of users. [Copyright &y& Elsevier]

This paper presents a new group key management protocol, CKC (Code for Key Calculation) for secure IP multicast. In this protocol which is based on logical key hierarchy, only the group key needs to be sent to new member at join. Then, using the group key current members and the new member calculate the necessary keys by node codes and one-way hash function. A node code is a random number assigned to each node to help users calculate necessary keys. Again, at leave server just sends the new group key to the remaining members. By this key, members calculate necessary keys using node codes and one-way hash function. The security of the keys is based on one-wayness of hash function. The results show that CKC reduces computational and communication overhead, and message size largely at join without increasing them at leave. [ABSTRACT FROM AUTHOR]

The arc fault circuit interrupter (AFCI) is expected to be one of the most essential components in smart grid systems for providing physical security and safety against electrical fire hazards caused by arc faults. As AFCIs are widely deployed as a part of mandatory installation requirements, a hierarchy consisting of multilevel AFCIs has been established, where a portable AFCI is connected serially to an outlet box AFCI. However, this multilevel AFCI structure causes serious problems when the AFCI detects arc faults in the surveillance area of its descendant AFCIs. This can cause de-energizing of the entire area covered by the upper-level AFCI, which may lead to blackouts over large areas. This paper proposes an integrated security framework comprised of physical and logical security measures as a solution for this problem. Firstly, the problem is tackled through communication between the hierarchy levels. Since the proposed system deals with physical security and safety, the communication must guarantee reliable message delivery within the specified deadlines. A controller area network (CAN) is chosen as the communication technology because it provides deterministic message delivery that meets the system requirements. Moreover, CAN has the advantages of verified performance and cost competitiveness through accelerated industrial adoption. Along with the physical security framework, a logical security framework is also proposed with group key management that prevents unauthorized access. Finally, this paper reports an integrated methodology for optimizing the design parameters satisfying the bandwidth and security demands of physical and logical measures because both demands competitively share a common communication resource. [ABSTRACT FROM PUBLISHER]

The group key management scheme that adopts the means of logical key hierarchy (LKH) is introduced, together with several improved schemes based on LKH. According to the needs and limitations of multicast applications in the schemes, the solutions to provide reliable security and high quality service at a minimal cost are analyzed. It is concluded that all these schemes make certain compromises and balances among security, quality of service and cost. The analysis of the motivation as well as the advantages or disadvantages for every improved scheme provides references for designing group key management scheme of specific multicast application according to the actual situation. [ABSTRACT FROM AUTHOR]

The Internet multicast capabilities have been used in enormous number of groups through the Internet. However, IP multicast does not deploy any mechanisms to secure the multicast messages in these groups. A lot of research efforts have been done to secure multicast messages. The idea behind the multicast security is to share a symmetric key between group members to encrypt/decrypt the multicast messages and to change this key after any membership change. The main re-keying problem is how to exchange the new group key between the group members in a scalable and secure way. In this paper we present a new multicast re-keying approach that is based on dividing the whole group into smaller subgroups. Each subgroup in turn is organized in a logical key hierarchy tree, and each subgroup member has the inverse key values of the other members in his subgroup in order to make the subgroup re-keying in a scalable and secure way. This decomposition, the proposed approach, which is named as Key Inverse Re-keying (KIR), reduces the multicast complexity from O(n) to O(log 2m) where n is the total number of the whole group members and m is the number of members in each subgroup. The performance of KIR is compared with that of other group re-keying approaches to prove its effectiveness. The comparison is undertaken according to the computational overhead, communication overhead, storage overhead, and message size. The results show that KIR enhances the group performance in terms of computational overhead and communication overhead especially at the leave operation which represents a big problem for most of the previous group re-keying protocols. [ABSTRACT FROM AUTHOR]

With the growing interest in converging fixed and mobile networks (FMC), mobile applications will require more and more resources from both the network and the mobile device. In such context, multicasting is essential because it lowers bandwidth consumption by simultaneously reaching a group of multiple recipients. Securing multicast flows has been extensively studied in the past, but none of the existing solutions were meant to handle the constraints imposed by mobile scenarios, in particular the high packet-loss rate. The need for a low overhead self-healing rekeying mechanism that is scalable, reliable and suitable for mobile environments has never been more urgent than with the arrival of FMC in 4G networks. This paper presents two self-healing recovery schemes based on the dual directional hash chains (DDHC) for the logical key hierarchy (LKH) rekeying protocol. This enables a member that has missed up to m consecutive key updates to recover the missing decryption keys without asking the group controller key server (GCKS) for retransmission. Conducted simulations show considerable improvements in the ratio of decrypted messages and in the rekey message overhead in high packet loss environments. [ABSTRACT FROM AUTHOR]

In this paper, we propose an efficient and a scalable protocol for secure multicast communication. This protocol is based on the Iolus and the logical key hierarchy protocols. It divides the whole group into several subgroups as in the Iolus protocol. Each subgroup in turn is organized in a logical key hierarchy as in the LKH protocol. This decomposition reduces the complexity for a member join or leave form O(n) to O(log m), where n is the number of the whole group members and m is the number of each subgroup members. The performance of the proposed protocol is compared with that of the Simple App., Iolus and LKH protocols. The comparison is undertaken according to the computational overhead, communication overhead, storage overhead, and message size. The results show that the proposed protocol enhances the group performance in terms of computation overhead, and communication overhead especially at the leave operation. [ABSTRACT FROM AUTHOR]

A sensor network operating in open environments requires a network-wide group key for confidentiality of exchanged messages between sensor nodes. When a node behaves abnormally due to its malfunction or a compromise attack by adversaries, the central sink node should update the group key of other nodes. The major concern of this group key update procedure will be the multi-hop communication overheads of the rekeying messages due to the energy constraints of sensor nodes. Many researchers have tried to reduce the number of rekeying messages by using the logical key tree. In this paper, we propose an energy-efficient group key management scheme called Topological Key Hierarchy (TKH). TKH generates a key tree by using the underlying sensor network topology with consideration of subtree-based key tree separation and wireless multicast advantage. Based on our detailed analysis and simulation study, we compare the total rekeying costs of our scheme with the previous logical key tree schemes and demonstrate its energy efficiency. [ABSTRACT FROM AUTHOR]

In this letter, we propose a decentralized group key management algorithm called DECLKH, which combines the logical key hierarchy (LKH) and the tree-based group Diffie- Hellman (TGDH) schemes. LKH is a centralized key distribution scheme, and thus, lacks fault-tolerance. On the other hand, TGDH is relatively inferior in terms of performance to LKH although it is fault-tolerant. The proposed algorithm, DECLKH, solves the single point of failure problems of LKH with much more enhanced performance than TGDH. [ABSTRACT FROM PUBLISHER]

The efficiency and security of secure group communication are dependent on the group key manager (GKM), which manages the group keys and membership. Although a GKM can employ any kind of group key management algorithm, we adopt the logical key hierarchy (LKH) for its efficiency and scalability. LKH is a tree-based group key management algorithm, which is more efficient when the key tree is balanced. However, only a few papers or documents have dealt with practical tree balancing techniques so far. In this letter, we propose LKH tree manager, an LKH key tree balancing algorithm that is efficient for a large and highly dynamic secure group. [ABSTRACT FROM PUBLISHER]

We study the issue of distributing cryptographic keys to a secure multicast group. The key management is focused on virtual tree-based schemes represented by the logical key hierarchy (LKH). We present the optimal key tree structure problem. Specifically, we address minimizing the computational overhead of the key server with analytical formulation and propose two new variations of LKH. The first one is based on hash functions while the second being an observably different approach of generating new keys based on existing ones. Both structures are investigated and optimized for the key server. [ABSTRACT FROM PUBLISHER]

Summary: In cloud environment, the importance of security for the outsourced data has increased much, since the data is maintained and controlled by the semi‐trusted third‐party cloud providers. Data Security is one of the major factors to be considered in group data sharing. Using the secret key, the entire file is encrypted directly in a conventional security framework; however, in a cloud‐based environment for group mechanism, this framework cannot be applied as there is a problem of key distribution. This research paper proposes an efficient hierarchical‐based group key mechanism for a cloud‐based environment. This proposed system relies on Key Distribution Server (KDS), which performs cryptographic key operations for securing the data in the cloud. Also, this system uses logical key hierarchy (LKH) protocol to maintain hierarchical tree for scalability. The group key is generated using the group member secret values and a secret value assigned by the KDS server. Performance analysis of this system shows that the proposed key management system is more efficient and much suitable for cloud environment. [ABSTRACT FROM AUTHOR]

With the development of 5G and the Internet of Things (IoT), mobile terminals are widely used in various applications under multicast scenarios. However, due to the limited computation resources of mobile terminals, reducing the computation cost of members in group key distribution processes of dynamic groups has become an important issue. In this paper, we propose a computation-efficient group key distribution (CEGKD) protocol. First, an improved secret sharing scheme is proposed to construct faster encryption and decryption algorithms. Second, the tree structure of logical key hierarchy (LKH) is employed to implement a simple and effective key-numbering method. Theoretical analysis is given to prove that the proposed protocol meets forward security and backward security. In addition, the experiment results show that the computation cost of CEGKD on the member side is reduced by more than 85% compared with that of the LKH scheme. [ABSTRACT FROM AUTHOR]

For wireless sensor networks, key management is a challenging issue because of the limited node resources, network size, and diverse requirements, depending on the exact application. This work presents CHAT, a key management scheme based on the well-known logical key hierarchy class of protocols. CHAT exploits topological network information to reduce rekeying costs and tessellates the network into topological clusters, to further localize rekeyings, leading to greater rekeying cost reductions. A modification that adds a network key is also presented, aiming to provide a group communication scheme which still incurs a low rekeying cost. [ABSTRACT FROM AUTHOR]