In 1976, Diffie and Hellman in their path breaking paper [5] proposed a two party key agreement protocol based on finite field. Diffie-Hellman Key Exchange Protocol [DH protocol] has unique importance in two party wireless communication scenarios. After this protocol several protocols have been proposed which were based on DH protocol but the Man in the middle attack raises a serious security concern on this protocol. Researchers have been working to overcome this security concern to design a new protocol. This paper proposes an authenticated key agreement protocol which is secure against Man in the middle attack. The authors also prove security issues of this protocol.

This communication suggests an orthogonal interleaver set for interleave division multiple access (IDMA) based non orthogonal multiple access (NOMA) schemes from beyond 5G viewpoint to support enormous increase in user count. The method generates an orthogonal interleaver set by providing two mother interleavers as seed to generate other users’ interleaving patterns progressively. The key feature of the proposed scheme is that it reduces implementation complexity and memory requirement at the base station, while implementing iterative multiuser detection (MUD), which most of the interlaever designs suggested in literature do not consider. It provides additional security to the user data due to progressively changing mother interleavers’ pattern along with the conventional purpose of providing unique identity for individual users in the system. The proposed orthogonal interleaver set is tested through simulations under multiple IDMA system configurations. It has been observed that it preserves the bit error rate (BER) performance of the IDMA scheme along with the optimal implementation complexity and minimal information exchange requirement between base station and mobile station to share the interleaver design.

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Braid groups were first introduced by Emil Artin in 1925. First cryptosystem, using Braid groups as a platform was discovered by Anshel et al in 2001. After the publication of this paper several cryptosystems on Braid groups had been designed. In this paper we have proposed a tripartite authenticated key agreement protocol using conjugacy problem which works in a braid group. We have proved that our protocol meet the security attributes under the assumption that the Braid Decomposition Problem (BDP) and the Conjugacy Search Problem (CSP) are hard in braid group.

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