Correct, this is part of the Signal protocol[1]. Specifically, this part is called Sesame[2]: > This document describes the Sesame algorithm for managing messa

Correct, this is part of the Signal protocol[1]. Specifically, this part is called Sesame[2]: > This document describes the Sesame algorithm for managing message encryption sessions in an asynchronous and multi-device setting. [1] https://www.signal.org/docs/ https://www.signal.org/docs/ [2] https://www.signal.org/docs/specifications/sesame/ https://www.signal.org/docs/specifications/sesame/