Multi-party Key Agreement Research Articles

A Robust Multi-Party Key Agreement Protocol Resistant to Malicious Participants

By its very nature, a non-authenticated multi-party key agreement protocol cannot provide participant and message authentication, so it must rely on an authenticated network channel. This paper presents the inability of two famous multi-party key agreement protocols to withstand malicious participant attacks, even though their protocols are based on the authenticated network channel. This attack involves a malicious participant disrupting the multi-party key agreement among honest participants. In this case, other honest participants do not correctly agree on a common key. Obviously, the malicious participant cannot obtain the common key either, and the communication confidentiality among participants is not breached. However, in some emergency situations or applications, a multi-party key agreement protocol design that is resistant to malicious participants is useful. Therefore, in this paper, a non-authenticated multi-party key agreement protocol resistant to malicious participants is proposed. The proposed robust protocol requires constant rounds to establish a common key. Each participant broadcasts a constant number of messages. Under the assumption of the Decision Diffie--Hellman problem and the random oracle model, we will show that the proposed protocol is provably secure against passive adversaries and malicious participants.

Multi-party authenticated key agreement protocols from multi-linear forms

Joux [Lect. Notes Comput. Sci., Vol. 1838, 2000, pp. 385–394] presented a one round protocol for tripartitie key agreement and Al-Riyami and Paterson [Report 2002/035, http://eprint.iacr.org, 2002] developed a number of tripartitie, one round, authenticated protocols related to MTI and MQV protocols. Recently, Boneh and Silverleg [Applications of Multi-linear Forms to Cryptography, Contemporary Mathematics, Vol. 324, Am. Math. Soc., Providence, RI, 2003, pp. 71–90] studied multi-linear forms, which provides a one round multi-party key agreement protocol. In this paper, we propose ( n+1) types of one round authenticated multi-party key agreement protocols from multi-linear forms based on the application of MTI and MQV protocols.

Multi-party key agreement protocols with cheater identification

In 2000, Pieprzyk and Li proposed two multi-party key agreement protocols based on secret sharing. The proposed protocols can achieve the following security goals: key freshness, key confidentiality, group authentication and key confirmation. However, this article points out that their protocols have a weakness for practical applications. A dishonest principal may disturb the protocol to fail, but anyone cannot identify the fraudulent principal. Therefore, an efficient cheater identification process is essential for multi-party key agreement protocols. Two improvements on their protocols are respectively proposed to remove this weakness. In our protocols, the extra computation overhead is small and security goals are not impaired.

MULTIPARTY KEY AGREEMENT PROTOCOL BASED ON SYMMETRIC TECHNIQUES

In this paper, we propose multiparty key agreement protocols by generalizing the Blom's scheme based on 2 variable polynomials. Especially we develop three party and four party key agreement schemes with security. The advantage of the new schemes is to have small demands on storage space.

Multiparty authentication services and key agreement protocols with semi-trusted third party

This paper introduces a new family of group key establishment protocols suitable for small or medium-sized groups. Five protocols are presented, using a semi-trusted server, with varying security service. The first one is a non-authenticated key agreement protocol suitable for applications with low security requirements. The second protocol adds an authenticated key agreement to provide collaborative authentication. The third and the fourth protocols provide key establishment with integrity and confirmation services, and the fifth protocol is the member adding protocol. A major advantage of the protocols is that they reduce the numbers of rounds from n to 5.

Key agreement in ad hoc networks

We encounter new types of security problems in ad hoc networks because such networks have little or no support infrastructure. In this paper we consider one such problem: a group of people in a meeting room do not have access to public key infrastructure or third party key management service, and they do not share any other prior electronic context. How can they set up a secure session among their computers? We examine various alternatives and propose new protocols for password-based multi-party key agreement in this scenario. Our protocols may be applicable in other scenarios, too. We also present a fault-tolerant version of a multi-party Diffie–Hellman key agreement protocol which can be of independent interest.

Multiparty key agreement protocols

A class of multiparty key agreement protocols based on secret sharing is presented. The trust infrastructure necessary to achieve the intended security goals is discussed. Entity authentication is suggested to be replaced by a less expensive group authentication. Two key agreement protocols are discussed. The first is the group key agreement where all principals must be active to call the conference. The other allows a big enough subgroup (controlled by the threshold parameter t) to trigger the conference. It is proved that the protocols achieve key freshness, key confidentiality, group authentication and key confirmation. A discussion about possible modifications and extensions of the protocol concludes the paper.