What Mechanism Ensures the Randomness and Fairness of Validator Selection?

The randomness and fairness of validator selection in PoS-based systems, including the PoS component of PoA, are typically ensured through a Verifiable Random Function (VRF). A VRF is a cryptographic function that produces a unique, non-forgeable, and publicly verifiable random output.

This output is then used to select the next set of validators, ensuring that the selection process is unpredictable and transparent to all participants.