SMART Credentials in the Multi-queue of Slackness (or Secure Management of Anonymous Reputation Traits without Global Halting)

Anonymous credentials encourage online communication without fear of surveillance, but may invite misbehavior like hate speech. Previous updatable anonymous credentials keep a chronological queue of authenticated sessions and a global pointer to the last chunk of judged sessions. This design allows efficient authentication for proving over only a subset of sessions. However, complications in subjective evaluation often introduce hard-to-judge sessions, which halt all users since sessions that come after the global pointer cannot be redeemed, eventually exceeding the queue size that limits the creation of bad sessions. Such a global-halting loophole may also make judgments overly harsh and hasty.We propose SMART (slack management of anonymous reputation traits), maintaining multiple queues so the server could issue interim judgments many times before finalization. Such slackness removes the binary judgment of old methods and mitigates the global-halting issue. Prior schemes only allow score upgrades (WPES ’14) or require proving against a global session list since the last checkpoint (S&P ’22). Our authentication time is linear in the number of queues or sessions in a designated queue for immediate revocation.