Abstract
The conventional authentication mechanisms in blockchain systems rely on trusted service provider and creden-tial authority, which are undesirable for the distributed systems and facing risk of single point of failure. Moreover, a consortium blockchain system may suffer from both inside attacks and linking attacks caused by the authorized nodes, leading to the privacy leakage and high security risk. To circumvent these impediments, a distributed anonymous authentication scheme with accountability is proposed in this paper. First of all, a recom-mendation mechanism is developed, where multiple authorized nodes in the consortium blockchain system act as referrers to authenticate a public node and to generate an initial anonymous credential for the authenticated node to join in the system. Then, a reputation update strategy is designed for all nodes based on the evaluation of their behaviors, so that their authorizations will be dynamically updated to control the security risk of the system. To be more specific, the referrers should be responsible for their applicants, resulting in a supervised authentication scheme, named accountability. Finally, we develop a credential update strategy based on the mix-context for defending against linking attacks, such that the privacy of real identity of a node and its transactions will be protected. The theoretical and numerical results demonstrate that our solution significantly improves the authentication performance and protects privacy in blockchain systems.
Published Version
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