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Abstract-With the extension in computer networks, there has been a drastic change in the disposition of network security. Security has always been a major concern of any organization as it involves mechanisms to ensure reliable access. In the present era of global electronic connectivity where hackers, eavesdroppers, electronic frauds, viruses are growing in number, security has proved to be indispensable. Although numerous solutions have been put forth in literature to guarantee security, they have botched with related traits like efficiency and scalability. Despite the range of security solutions that have been presented by experts, not a single approach has been wholly agreed upon to provide absolute security or standardized upon unanimously. Furthermore, these approaches lack adoptable user implementation. In this paper, various approaches and techniques that were introduced in the past for the purpose of enhancing the authentication and authorization of the user while performing sensitive and confidential transaction are discussed. Each of works performed by the researchers is taken singlehandedly for debate followed by analysis. Finally, the open issues in the current domain of study are formulated from the review conducted.

N‐Hydroxypthalimide (NHPI) has become a powerful and versatile organocatalyst, it has been known to catalyze various free‐radical processes leading to the wide range of organic transformations. Primarily, phthalimido‐N‐oxyl (PINO) radical formed from NHPI is highly efficient abstraction species for carrying out radical chain reactions. In this review, we have discussed about the most important and successful reactions from last six years, with their plausible reaction mechanisms. This review broadly covers the type of bond formation such as carbon‐carbon, carbon‐oxygen and carbon‐nitrogen bond formations. We have also highlighted various types of reaction strategies where in combination with divergent reagent systems it helps to construct different types of molecules which further find applications in the synthesis of complex set of biologically active molecule. NHPI catalyzed oxidation reactions of different class of organic compounds are also reviewed.

A Ni-catalyzed direct access to various pyrano cis-fused dihydro benzofurans and indoles from unsaturated enopyranoses and o-iodo phenols/anilines is developed.