(* modified version of sha_padding_lemmas.pad *)
Definition pad_inc (msg : list byte) : list byte :=
  let n := BlockSize + Zlength msg in
  msg ++ [Byte.repr 128%Z]
      ++ list_repeat (Z.to_nat (-(n + 9) mod 64)) Byte.zero
      ++ intlist_to_bytelist ([Int.repr (n * 8 / Int.modulus); Int.repr (n * 8)]).Definition sha_splitandpad_inc (msg : Blist) : Blist :=
  bytesToBits (pad_inc (bitsToBytes msg)).

Lemma sha_h_length iv blk: length iv = c -> length blk = b -> length (sha_h iv blk) = c.