"Verifiably random" means produced using a process where it isn't possible for you to know the outcome. In this case, saying "the key is [X], which is the SHA-2 hash of [Y]" would allow you to know that they couldn't choose [X] without breaking SHA-2.
"Verifiably random" means produced using a process where it isn't possible for you to know the outcome. In this case, saying "the key is [X], which is the SHA-2 hash of [Y]" would allow you to know that they couldn't choose [X] without breaking SHA-2.