The goal was to use a visual/motion language that was consistent, familiar to the consumer, and easily scalable across the Microsoft platform/ecosystem. To clearly communicate each step in the authentication process in a very simplified manner.
My inspiration was a play based of the "peek" iconology present in many password input fields. This design was rapidly received well with minimum push back throughout the entire company and quickly adopted and implemented in late 2015. The design is still used to this day, some nearly four years later. ( Late 2018 )