To ensure confidentiality and avoid humain attacks against our data, we exchange encryption decryption keys. In proposal scheme, use the commutative properties of product circular matrices to create a common key by applying protocol { \it Diffie-Hellman} through classic channel. raise security level system have introduced sensibility chaotic logistic maps in another which is $BB84$ throuth quan...

We show that in applications that use the Diffie-Hellman (DH) transform but take care of hashing the DH output (as required, for example, for secure DH-based encryption and key exchange) the usual requirement to work over a DDH group, i.e., a group in which the Decisional Diffie-Hellman assumption holds, can be relaxed to only requiring that the DH group contains a large enough DDH subgroup. In...

Secure group protocols are not easy to design: this paper will show new attacks found against a protocol suite for sharing key. The method we propose to analyse these protocols is very systematic, and can be applied to numerous protocols of this type. The A-GDH.2 protocols suite analysed throughout this paper is part of the Cliques suites that propose extensions of the Diffie-Hellman key exchan...

authenticated Diffie-Hellman key exchange allows two principals communicating over a public network, and each holding public/private keys, to agree on a shared secret value. In this paper we study the natural extension of this cryptographic problem to a group of principals. We begin from existing formal security models and refine them to incorporate major missing details (e.g., strong-corruptio...

A generalization of the original Diffie-Hellman key exchange in (Z/pZ) found a new depth when Miller [27] and Koblitz [16] suggested that such a protocol could be used with the group over an elliptic curve. In this paper, we propose a further vast generalization where abelian semigroups act on finite sets. We define a Diffie-Hellman key exchange in this setting and we illustrate how to build in...

A generalization of the original Diffie-Hellman key exchange in (Z/pZ) found a new depth when Miller [27] and Koblitz [16] suggested that such a protocol could be used with the group over an elliptic curve. In this paper, we propose a further vast generalization where abelian semigroups act on finite sets. We define a Diffie-Hellman key exchange in this setting and we illustrate how to build in...

Recently, M. Abdalla et al. proposed a slightly different variant of AuthA, based on the scheme proposed by E. Bresson et al., and provided the first complete proof of forward-secrecy for AuthA. They claimed that under the Gap Diffie-Hellman assumption the variant of AuthA was forward-secure in the random-oracle model. In this paper, we present an active attack to reveal a previously unpublishe...

Authenticated multiple key exchange (AMKE) protocols not only allow participants to warrant multiple session keys within one run of the protocol but also ensure the authenticity of the other party. Many AMKE protocols using bilinear pairings have been proposed. However, the relative computation cost of the pairing is approximately twenty times higher than that of the scalar multiplication over ...

Garg, Gentry and Halevi (GGH) described the first candidate multilinear maps using ideal lattices. However, Hu and Jia recently presented an efficient attack for two applications based on the GGH map, multipartite Diffie-Hellman key exchange and an instance of witness encryption using 3-exact cover problem. In this paper, we describe a modification construction of multilinear maps from ideal la...