How to Grant Anonymous Access

In this paper, we propose three protocols to share, among a set of <inline-formula> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> competing entities, the responsibility to grant anonymous access to a resource. The protocols we propose vary in their settings to take into account central or distributed registration. We prove that any subset of guardian authorities can neither tamper with, nor forge, new access-key tokens. Besides, two of the methods we propose are resistant to the eventual appearance of quantum computers. The protocols we propose permit new approaches for cryptographic applications such as electronic voting or blockchain access.