Dynamic Peer Group (DPG) applications, such as video-conferencing and multi-user gaming environments have proliferated the internet and group-key agreement protocols are critical in securing DPG communication. Identity-based cryptosystems avoid certificate management complications inherent to traditional public-key systems but introduce key escrow, which is highly undesirable in most applications. We design a scalable technique to eliminate key escrow and develop a distributed, escrow-less identity-based group-key agreement protocol for securing resource-constrained DPG communication. The proposed protocol is provably secure against passive adversaries, resilient to active attacks, scalable and more cost effective than any such protocol. We provide a detailed theoretical analysis to support the claims.
Dynamic Peer Group (DPG) applications, such as video-conferencing and multi-user gaming environments have proliferated the internet and group-key agreement protocols are critical in securing DPG communication. Identity-based cryptosystems avoid certificate management complications inherent to traditional public-key systems but introduce key escrow, which is highly undesirable in most applications. We design a scalable technique to eliminate key escrow and develop a distributed, escrow-less identity-based group-key agreement protocol for securing resource-constrained DPG communication. The proposed protocol is provably secure against passive adversaries, resilient to active attacks, scalable and more cost effective than any such protocol. We provide a detailed theoretical analysis to support the claims.
Modern collaborative and group-oriented applications typically involve communications over open networks. Given the openness of today's networks, communications among group members must be secure and, at the same time, efficient. Group key agreement (GKA) is widely employed for secure group communications in modern collaborative and group-oriented applications. This paper studies the problem of GKA in identity-based cryptosystems with an emphasis on round-efficient, sender-unrestricted, member-dynamic, and provably secure key escrow freeness. The problem is resolved by proposing a one-round dynamic asymmetric GKA protocol which allows a group of members to dynamically establish a public group encryption key, while each member has a different secret decryption key in an identity-based cryptosystem. Knowing the group encryption key, any entity can encrypt to the group members so that only the members can decrypt. We construct this protocol with a strongly unforgeable stateful identity-based batch multisignature scheme. The proposed protocol is shown to be secure under the k -bilinear Diffie-Hellman exponent assumption.
Key escrow is a default property that is inherent in identity-based cryptography, where a curious private key generator (PKG) can derive a secret value shared by communicating entities in its domain. Therefore, a dishonest PKG can encrypt and decrypt ciphers or can carry out any attack on the communicating parties. Of course, the escrow property is not completely unwanted but is acceptable in other particular applications. On the other hand, in more civil applications, this key escrow property is undesirable and needs to be removed to provide maximum communication privacy. Therefore, this paper presents an escrow-free identity-based key agreement protocol that is also applicable even in a distinct PKG condition that does not use pairings. The proposed protocol has comparable computational and communicational performance to many other protocols with similar security attributes, of which their security is based on costly bilinear pairings. The protocol’s notion was inspired by McCullagh et al. and Chen-Kudla, in regard to escrow-free and multi-PKG key agreement ideas. In particular, the scheme captures perfect forward secrecy and key compromise impersonation resilience, which were lacking in McCullagh et al.’s study, as well as all other desirable security attributes, such as known key secrecy, unknown key-share resilience and no-key control. The merit in the proposed protocol is the achievement of all required security requirements with a relatively lower computational overhead than many other protocols because it precludes pairings.
Through the group key agreement, all group members could negotiate a common session key which is used in later secure communication.While simple GKA cannot provide enough security to resist the adversary's attack, and the malicious damage during the agreement makes the authenticated key agreement particularly important.In identity-based authentication, user's unique identity information is used as the public key, which makes it exempt from a series of management of the certification in public-key infrastructure.Thereby, the identity-based key agreement can simplify the key management procedures and reduce the risk of failure at the certification authority.Recently, several identity-based group key agreement protocols have been proposed, however most of them are either vulnerable to impersonation and replay attack or inefficient and unscalable.This paper proposes a novel authenticated group key agreement protocol which is based on bilinear pairings.It needs two rounds to negotiate the session key, and the low computational complexity makes the protocol efficient and scalable.Meanwhile, our protocol also ensures the forward and backward secrecy and the key independence.Under the Decisional Diffie-Hellman assumption, our protocol is proved to be secure against the adversary. 1.
A recent primitive known as asymmetric group key agreement (AGKA) allows a group of users to negotiate a common encryption key which is accessible to any entities and corresponds to different decryption keys, each of which is only computable by one group member. This concept makes it easy to construct distributed and one-round group key agreement protocols. However, this existing instantiation depends on public key infrastructure (PKI) associated with certificate management, or it is only secure against passive adversaries. This paper addresses this concern by designing a certificateless authenticated AGKA scheme, which does not require certificates to guarantee the authenticity of public keys yet avoids the inherent escrow problem of identity-based cryptosystems. Using simple binding techniques, the proposed scheme can be raised to the same trust level as that using the traditional PKI. We show that the proposed protocol is secure provided that the underlying k-bilinear Diffie–Hellman exponent problem is hard.
Group key agreement (GKA) is a cryptographic primitive allowing two or more users to negotiate a shared session key over public networks.Wu et al. recently introduced the concept of asymmetric GKA that allows a group of users to negotiate a common public key, while each user only needs to hold his/her respective private key.However, Wu et al.'s protocol can not resist active attacks, such as fabrication.To solve this problem, Zhang et al. proposed an authenticated asymmetric GKA protocol, where each user is authenticated during the negotiation process, so it can resist active attacks.Whereas, Zhang et al.'s protocol needs a partially trusted certificate authority to issue certificates, which brings a heavy certificate management burden.To eliminate such cost, Zhang et al. constructed another protocol in identity-based setting.Unfortunately, it suffers from the so-called key escrow problem.In this paper, we propose the certificateless authenticated asymmetric group key agreement protocol which does not have certificate management burden and key escrow problem.Besides, our protocol achieves known-key security, unknown key-share security, key-compromise impersonation security, and key control security.Our simulation based on the pairing-based cryptography (PBC) library shows that this protocol is efficient and practical.
The members in the dynamic peer group (DPG) are divided into several clusters according to linker cluster architecture (J.B. Dennis and E. Anthony, 1981). In each cluster, the members perform the BD protocol (M. Burmester and Y. Desmedt, 1994) to establish the cluster key and the TGDH protocol (Y. Kim et al., 2004) is performed among the clusters to generate the group key. This method can not only avoid the weakness of AKA (auxiliary key agreement) of BD, but also reduce the computation cost of TGDH scheme. In our scheme the members have been authenticated based identity, and we prove the security in random oracle model.