Strongly Secure Authenticated Key Exchange from Ideal Lattices

In this paper, we propose an efficient and practical authenticated key exchange (AKE) protocol from ideal lattices, which is well-designed and has some similarity to the HMQV protocol. Using the hardness of the graded discrete logarithm (GDL) problem and graded decisional Diffie-Hellman (GCDH) problem, the proposed protocol is provably secure in the extended Canetti-Krawczyk model

Securing group key exchange against strong corruptions and key registration attacks

Abstract: In Group Key Exchange (GKE) protocols, users usually extract the group key using some auxiliary (ephemeral) secret information generated during the execution. Strong corruptions are attacks by which an adversary can reveal these ephemeral secrets, in addition to the possibly used long-lived keys. Undoubtedly, security impact of strong corruptions is serious, and thus specifying appropriate security requirements and designing secure GKE protocols appears an interesting yet challenging task -the aim of our article. We start by investigating the current setting of strong corruptions and derive some refinements like opening attacks that allow to reveal ephemeral secrets of users without their long-lived keys. This allows to consider even stronger attacks against honest, but 'opened' users. Further, we define strong security goals for GKE protocols in the presence of such powerful adversaries and propose a 3-round GKE protocol, named TDH1, which remains immune to their attacks under standard cryptographic assumptions. Our security definitions allow adversaries to register users and specify their longlived keys, thus, in particular capture attacks of malicious insiders for the appropriate security goals such as Mutual Authentication, key confirmation, contributiveness, key control and keyreplication resilience. Keywords: authenticated group key exchange; GKE; contributiveness; insider attacks; key registration; mutual authentication; MA; strong corruptions; tree Diffie-Hellman; TDH1. Reference to this paper should be made as follows: Biographical notes: Emmanuel Bresson received his PhD at the École normale supérieure in Paris. He works as a Cryptography Expert for government teams. His main research subjects involve key exchange mechanisms and authentication for multi-party protocols with provable security. He has published his work in many international conference papers and security focusing journals. Mark Manulis received his PhD in Computer Science from the Ruhr University Bochum in 2007. His research focuses on security and cryptography related to key management, authentication, anonymity and privacy in distributed applications and (wireless) communications

Survey on Security Requirements and Models for Group Key Exchange

In this report we provide an analytical survey on security issues that are relevant for group key exchange (GKE) protocols. We start with the description of the security requirements that have been informally described in the literature and widely used to analyze security of earlier GKE protocols. Most of these definitions were originally stated for two-party protocols and then adapted to a group setting. These informal definitions are foundational for the later appeared formal security models for GKE protocols whos

Survey on Security Requirements and Models for Group Key Exchange

In this paper we provide an analytical survey on security issues that are relevant for group key exchange protocols. We start with the description of the security requirements that have been informally described in the literature and widely used to analyze security of earlier group key exchange protocols. Most of these definitions were originally stated for two-party protocols and then adapted to a group setting. These informal definitions are foundational for the later appeared formal security models for group key exchange protocols whose development, strengths, and weaknesses are also described and analyzed