Goal forall k' v, bitsToBytes (to_list (HMAC_Bvec k' v)) = HMAC256  (bitsToBytes v) (bitsToBytes (to_list k')).

Lemma Genloop_Zlength_blocks : forall n eta k f v blocks u, @Gen_loop eta f k v n = (blocks,u) -> Zlength blocks = Z.of_nat n.