A Selectable κ-Times Relaxed Anonymous Authentication Scheme

摘要

In a κ-Times Anonymous Authentication (κ-TAA) scheme, Application Providers (APs) authenticates each group member in k times. A user can preserve his/her own privacy and an AP can restrict the number of used services to just κ -times, since users are identified if they access an AP more than k times. In all previous schemes, each AP assumes the same k for all users. Added to this, total anonymity of unlinkability requires large computation amount such as pairing computations compared with non-anonymous schemes. In this paper, we propose a selectable κ-TAA scheme with relaxed anonymity. Relaxed anonymity is an intermediate level of privacy required between total anonymity and linkability, where authentication executions for the same AP are linkable, but an authentication execution with an AP v0 and an authentication execution with an AP v1 (v0≠v1) are unlinkable. Our authentication algorithm is efficient than existing ones thanks to this relaxed notion.