11.1. BABE digest messages
The Runtime is required to provide the BABE authority list and randomness to the host via a consensus message in the header of the first block of each epoch.
The digest published in Epoch is enacted in . The randomness in this digest is computed based on the all the VRF outputs up to including Epoch while the authority set is based on all transaction included up to Epoch .
The computation of the randomeness seed is described in Epoch-Randomness which uses the concept of epoch subchain as described in host specification and the value , which is the VRF output computed for slot .
Algorithm 31. Epoch Randomness
where is the epoch index.