In the current globalization scenario, many group communication applications have become vital and the users not only subscribe to a single resource, but they use multiple resources and hence ending up with multi-privileged groups. In some group communication applications, it is desirable to encrypt the contents without exact knowledge of the set of intended receivers. Attribute based encryptio...

We propose two schemes for efficient broadcast key establishment that enables a sender to communicate to any subset of the user-base by allowing a small ratio of free-riders. The schemes do not require stateful receivers and one scheme is unconditionally secure. The free-riders are unable to learn from the past whether they might become free-riders for a certain transmission again. We present a...

We build the first public-key broadcast encryption systems that simultaneously achieve adaptive security against arbitrary number of colluders, have small system parameters, and have security proofs that do not rely on knowledge assumptions or complexity leveraging. Our schemes are built from either composite order multilinear maps or obfuscation and enjoy a ciphertext overhead, private key siz...

This paper puts forward an efficient broadcast encryption in public key setting employing ternary tree subset difference method for revocation. It provides outsider anonymity disabling the revoked users from getting any information of message and concealing the set of subscribed users from the revoked users. Our approach utilizes composite order bilinear group setting and exhibits significant i...

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...

As the low maintenance, cloud computing supply an capable solution for sharing group resource within cloud users. Sharing data with the two or more owners while preserving data and identity privacy from an un-trusted cloud is still an issue, due to the frequent change of the membership. In this paper, we propose a secure data sharing scheme for dynamic subgroups in the cloud. By using group sig...

This document describes an architecture for secure service replication in an asynchronous network like the Internet, where a malicious adversary may corrupt some servers and control the network. The underlying protocols for Byzantine agreement and for atomic broadcast rely on recent developments in threshold cryptography. These assumptions are discussed in detail and compared to related work fr...

In this paper we consider anonymity in the context of Broadcast Encryption (BE). This issue has received very little attention so far and all but one of the currently available BE schemes fail to provide anonymity. Yet, we argue that it is intrinsically desirable to provide anonymity in standard applications of BE and that it can be achieved at a moderate cost. We provide a security definition ...

Broadcast encryption (BE) is a cryptographic primitive that allows a broadcaster to encrypt digital content to a privileged set of users and in this way prevent revoked users from accessing the content. In BE schemes, a group of users, called traitors may leak their keys and enable an adversary to receive the content. Such malicious users can be detected through traitor tracing (TT) schemes. Th...