Anon-Pass is a practical anonymous subscription system. It provides users the guarantee that a service provider cannot link different authenticated sessions to particular users any better than random guessing. However, it also provides a service provider proper admission control: that is, no more users may authenticate than have previously registered.
Anon-Pass: Practical Anonymous SubscriptionsProceedings of the 34th IEEE Symposium on Security and Privacy (S&P), San Francisco, CA, May 2013.In the
Source code can be found on github.