Definition shah : Blist -> Blist ->  Blist := sha_h.Definition hashblock : list int -> list int -> list int := SHA256.hash_block.Definition HHB : shah =
      (fun rgs bl : Blist =>
       intsToBits (hashblock (bitsToInts rgs) (bitsToInts bl))).Definition hashblocks: list int -> list int -> list int := SHA256.hash_blocks.Definition d:nat := 16%nat.Definition HBS_eq : forall r msg : list int,
         hash_blocks r msg =
         match msg with
         | List.nil => r
         | _ :: _ => hash_blocks (hash_block r (firstn d msg)) (skipn d msg)
         end := hash_blocks_equation.Module PAD := HMAC_Pad SHA256 I256.

Theorem HMAC_pad_concrete (K : list byte) (M H : list byte) (OP IP : byte) (k m h : Blist) (op ip : Blist): ((length K) * 8)%nat = (c + p)%nat -> bytes_bits_lists k K -> bytes_bits_lists m M -> bytes_bits_lists op (HMAC_SHA256.sixtyfour OP) -> bytes_bits_lists ip (HMAC_SHA256.sixtyfour IP) -> sha.HMAC_spec_pad.HMAC c p B sha_h sha_iv sha_splitandpad op ip k m = h -> HMAC_SHA256.HmacCore IP OP M K = H -> bytes_bits_lists h H.