Stayin' Alive: Aliveness as an Alternative to Authentication

Authentication protocols attempt to discern whether or not a user is who she says she is based on what she has, is or knows. In many situtations, however, such as protecting Wikis from robots and Distributed Hash Tables from sybils, identity is less important than liveness: it's not who you are that matters, it's whether or not you are alive. We propose extensions to the Kerberos authentication which allow systems to test whether or not they are interacting with a real person, optionally disregarding their identity. We demonstrate how such extensions could be used to support realistic user interactions with requiring shared definitions of global identity.