Efficient group key exchange protocol with strong security

JiKai Teng, Chuan-Kun Wu, Chunming Tang +1 more

Junghyun Nam, Dongho Won

A group key exchange protocol is a cryptographic primitive that describes how a group of parties communicating over a public network can come up with a common secret key. Due to its significance both in network security and cryptography, the design of secure and efficient group key exchange protocols has attracted many researchers' attention over the years. However, despite all the efforts undertaken, there seems to have been no previous systematic look at the growing problem of key exchange over combined wired and wireless networks which consist of both stationary computers with sufficient computational capabilities and mobile devices with relatively restricted computing resources. In this paper, we present the first group key exchange protocol that is specifically designed to be well suited for this rapidly expanding network environment. Our construction meets simplicity, efficiency, and strong notions of security.

Lihong He

Zheng Yang

Nowadays many crucial network applications rely on the existence of a confidential channel established by authenticated key exchange (AKE) protocols over public networks.With the rapid development of cyber technology, novel attacks to cryptosystem emerge in an endless stream.This has also led to the development of AKE solutions to provide increasingly stronger security guarantees.In this thesis we focus on provision of practical constructions for AKE protocols which are provably secure in a strong sense without resorting to random oracles.We first we present three new efficient compilers to generically turn passively secure key exchange protocols (KE) into authenticated key exchange protocols (AKE) where security also holds in the presence of active adversaries.Our compilers are not only a useful tool for the design of new AKE systems with many additional security properties in a modular and less error-prone fashion, but they also help to relax the assumptions on existing, practical key exchange mechanisms which are not known to be provably secure AKE protocols.Security of our compilers is shown in a strong modified CK model where the adversary is allowed to reveal either long-term secret key or state information of the protocol participants.On the second, we study the open problem on constructing eCK secure two party AKE protocol without random oracles and NAXOS trick.A generic construction satisfying those requirements is given based on well-known cryptographic primitives following the guideline of efficiency.Then a concrete protocol is proposed which is the first eCK secure protocol in the standard model under both standard assumptions and post-specified peer setting (i.e.without knowing any cryptographic information about its communication peer).Both proposed schemes can be more efficiently implemented with secure device than previous works which are eCK secure in the standard model, where the secure device might be normally used to store the long-term private key and to implement codes of protocol which need to be resilience of state leakage.Finally, we generalize our one-round two party AKE construction to group case that yields an efficient tripartite AKE protocol based on bilinear maps and a candidate group AKE protocol (with more than three members) based on multilinear maps.Up to now they are the first solutions which can be proved secure in the g-eCK model without random oracles.Meanwhile we make first step to show how to simplify the security proof for one-round group AKE under g-eCK model.i

Jonathan I. Katz, Moti M. Yung

Emmanuel Bresson, Mark Manulis

In a group key exchange (GKE) protocol, the resulting group key should be computed by all participants such that none of them can gain any advantage concerning the protocol's output: misbehaving participants might have personal advantage in influencing the value of the group key. In fact, the absence of trust relationship is the main feature of GKE (when compared with group key transport) protocols. The existing notions of security are enlarged by identifying limitations in some previously proposed security models while taking into account different types of corruptions (weak and strong). To illustrate these notions, two efficient and provably secure generic solutions, compilers, are presented.