The third important aspect of security is encryption to transfer messages among the users in a secure manner. Group key management discussed in the earlier chapter is applicable for transferring messages securely to the members in a group. Apart from transferring messages to the members in a group, messages can be transferred securely to an individual user. Encryption plays a major role in such...

Lei et al. [26] proposed a new asymmetric group key agreement protocol allowing a set of users to negotiate a common encryption key accessible by any user, and each user holds her respective decryption key. This enables the confidential message communication among group users, and grants any outsider to send message to the group. In this paper, an authenticated asymmetric group key agreement pr...

Multicast routing protocols are widely used as efficient communication methods for Group-oriented applications. Decentralized system is preferred to improve bandwidth economization. However, security with the key management for such protocols re-mains a significant problem. In this paper, a secure group key agreement over decentralized systems is proposed. The proposed system is based on the us...

We define a framework to reason about implementations of equational theories in the presence of an adaptive adversary. We particularly focus on soundess of static equivalence. We illustrate our framework on different equational theories: symmetric encryption, modular exponentiation and also joint theories of encryption and modular exponentiation. Finally, we define a model for symbolic analysis...

We present a hybrid group key management protocol that incorporates both a centralized and a contributory scheme for key management, and a tree-based Elliptic Curve Diffie-Hellman technique for group key updates. It combines the advantage of the centralized approach’s efficiency and the contributory scheme’s fault tolerance. In addition, our rekeying algorithm updates the group key in the prese...

We extend the well-known Tree-Diffie-Hellman technique used for the design of group key exchange (GKE) protocols with robustness, i.e. with resistance to faults resulting from possible system crashes, network failures, and misbehavior of the protocol participants. We propose a fully robust GKE protocol using the novel tree replication technique: our basic protocol version ensures security again...

Emerging applications require secure group communications around hierarchical architecture protocols, like military or public emergency applications. However, conceiving such secure hierarchical protocols is not straightforward. Thus, their verification become a primordial issue in order to avoid the possible security attacks and vulnerabilities. Several attempts have been done to deal with for...

Most practical applications use hybrid encryption to deal with large plaintext messages since the efficiency of the public key encryption algorithm is low. As a main part of hybrid encryption schemes, Key Encapsulation Mechanism (KEM) allows a sender to generate a random session key and distribute it to recipient. In some communication scenario, one-to-group model is of importance. In this pape...

The rapid and promising development of applications and communication systems designed for groups of participants like groupware, computer supported collaborative work systems, or digital conference systems implies exigence of mechanisms providing adequate security properties. These mechanisms can be designed based on the foundations of cryptography. Group key exchange protocols are multi-party...

Attribute based systems enable fine-grained access control among a group of users each identified by a set of attributes. Secure collaborative applications need such flexible attribute based systems for managing and distributing group keys. However, current group key management schemes are not well designed to manage group keys based on the attributes of the group members. In this paper, we pro...