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

Lemma HMAC_DRBG_generate_helper_Z_equation': forall (HMAC : list byte -> list byte -> list byte) (key v : list byte) (requested_number_of_bytes : Z), 0 < requested_number_of_bytes -> HMAC_DRBG_generate_helper_Z HMAC key v requested_number_of_bytes = let (v0, rest) := HMAC_DRBG_generate_helper_Z HMAC key v (requested_number_of_bytes - Z.of_nat 32) in (HMAC v0 key, rest ++ HMAC v0 key).