Key Transparency can be used as a Public Key discovery service to authenticate users and provides a mechanism to keep the Service Provider accountable.
Key Transparency can be used by account owners to reliably see what keys have been associated with their account, and it can be used by senders to see how long an account has been active and stable before trusting it.
Key Transparency is inspired by CONIKS and Certificate Transparency. It is a work-in-progress with several milestones under development.