A family of authenticators based on static shared keys is identified and proven secure. The authenticators can be used in a variety of settings, including identity-based ones. Application of the authenticators to Diffie-Hellman variants in appropriate groups leads to authenticated key agreement protocols which have attractive properties in comparison with other proven-secure protocols. We explo...

This paper presents a new identity based key agreement protocol. In id-based cryptography (introduced by Adi Shamir in [33]) each party uses its own identity as public key and receives his secret key from a master Key Generation Center, whose public parameters are publicly known. The novelty of our protocol is that it can be implemented over any cyclic group of prime order, where the Diffie-Hel...

We give a new two-pass authentication scheme, which is a generalisation of an authentication scheme of Sibert-Dehornoy-Girault based on the Diffie-Hellman conjugacy problem. Compared to the above scheme, for some parameters it is more efficient with respect to multiplications. We sketch a proof that our authentication scheme is secure.

In a group Diffie–Hellman (GDH) key agreement protocol, all group members collaboratively establish a group key. Most GDH key agreement protocols took natural generalization of the original Diffie–Hellman (DH) key agreement protocol to arrange all group members in a logic ring or a binary tree and to exchange DH public keys. The computational cost and the communication rounds are the two most i...

A group key agreement protocol is designed to efficiently implement secure multicast channels for a group of parties communicating over an untrusted, open network by allowing them to agree on a common secret key. In the past decade many problems related to group key agreement have been tackled and solved (diminished if not solved), and recently some constant-round protocols have been proven sec...

We study the composition of security protocols when protocols share secrets such as keys. We show (in a Dolev-Yao model) that if two protocols use disjoint cryptographic primitives, their composition is secure if the individual protocols are secure, even if they share data. Our result holds for any cryptographic primitives that can be modeled using equational theories, such as encryption, signa...

Abstract We propose the first tight security proof for ordinary two-message signed Diffie–Hellman key exchange protocol in random oracle model. Our is based on strong computational assumption and multiuser of a digital signature scheme. With our proof, DH can be deployed with optimal parameters, independent number users or sessions, without need to compensate any loss. abstract approach new not...

Tripartite (Diffie-Hellman) Key Exchange (3KE), introduced by Joux (ANTS-IV 2000), represents today the only known class of group key exchange protocols, in which computation of unauthenticated session keys requires one round and proceeds with minimal computation and communication overhead. The first one-round authenticated 3KE version that preserved the unique efficiency properties of the orig...

Diffie-Hellman is public key based symmetric key algorithm used for secret key sharing between two parties over public communication channel. Diffie-Hellman is weak when there is man in middle attack done by eavesdropper. Diffie-Hellman algorithm is not provide authentication. Security of Diffie-Hellman cryptography system completely depends upon random prime number selected by user. Finding pr...

Whether the discrete logarithm problem can be reduced to the Diffie–Hellman problem is a celebrated open question. The security of Diffie–Hellman key exchange and other cryptographic protocols rests on the assumed difficulty of the computational Diffie–Hellman problem; such a reduction would show that this is equivalent to assuming that computing discrete logarithms is hard. What is known is th...