Definition bxorlist := combinelist _ Byte.xor.Definition Bl2VL (l: list byte) := map Vint (map Int.repr (map Byte.unsigned l)).Inductive CONTENT SIGMA K (mInit:val) (mCont zbytes:list byte): nat -> list byte -> list byte -> Prop :=
  CONT_zero: CONTENT SIGMA K mInit mCont  zbytes O zbytes nil
| CONT_succ: forall n zN resN ,
             CONTENT SIGMA K mInit mCont zbytes n zN resN ->
             forall d,
             SixteenByte2ValList d = Bl2VL (ZCont n zbytes) ->
             forall snuff srbytes Xor,
             Snuffle20 (prepare_data (d, SIGMA, K)) = Some snuff ->
             QuadChunks2ValList (map littleendian_invert snuff) =
                map Vint (map Int.repr (map Byte.unsigned srbytes)) ->
             bxorlist (bytes_at mInit (Z.of_nat n * 64) 64 mCont) srbytes = Some Xor ->
             CONTENT SIGMA K mInit mCont zbytes (S n) (snd (ZZ zN (8:nat))) (resN++Xor).Inductive CONTENT SIGMA K (mInit:val) (mCont zbytes:list byte): nat -> list byte -> list byte -> Prop :=
  CONT_zero: CONTENT SIGMA K mInit mCont  zbytes O zbytes nil
| CONT_succ: forall n zN resN ,
             CONTENT SIGMA K mInit mCont zbytes n zN resN ->
             forall d,
             SixteenByte2ValList d = Bl2VL (ZCont n zbytes) ->
             forall snuff srbytes Xor,
             Snuffle20 (prepare_data (d, SIGMA, K)) = Some snuff ->
             QuadChunks2ValList (map littleendian_invert snuff) =
                map Vint (map Int.repr (map Byte.unsigned srbytes)) ->
             bxorlist (bytes_at mInit (Z.of_nat n * 64) 64 mCont) srbytes = Some Xor ->
             CONTENT SIGMA K mInit mCont zbytes (S n) (snd (ZZ zN (8:nat))) (resN++Xor).Inductive CONTENT SIGMA K (mInit:val) (mCont zbytes:list byte): nat -> list byte -> list byte -> Prop :=
  CONT_zero: CONTENT SIGMA K mInit mCont  zbytes O zbytes nil
| CONT_succ: forall n zN resN ,
             CONTENT SIGMA K mInit mCont zbytes n zN resN ->
             forall d,
             SixteenByte2ValList d = Bl2VL (ZCont n zbytes) ->
             forall snuff srbytes Xor,
             Snuffle20 (prepare_data (d, SIGMA, K)) = Some snuff ->
             QuadChunks2ValList (map littleendian_invert snuff) =
                map Vint (map Int.repr (map Byte.unsigned srbytes)) ->
             bxorlist (bytes_at mInit (Z.of_nat n * 64) 64 mCont) srbytes = Some Xor ->
             CONTENT SIGMA K mInit mCont zbytes (S n) (snd (ZZ zN (8:nat))) (resN++Xor).

Lemma ZZ_Zlength: forall n zbytes u U, ZZ zbytes n = (u,U) -> Zlength zbytes=16 -> Z.of_nat n <= 8 -> Zlength U = 16.