--  Copyright (C) 2015  Daniel Otte <bg@nerilex.org>
--
--  This program is free software: you can redistribute it and/or modify
--  it under the terms of the GNU General Public License as published by
--  the Free Software Foundation, either version 3 of the License, or
--  (at your option) any later version.
--
--  This program is distributed in the hope that it will be useful,
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
--  GNU General Public License for more details.
--
--  You should have received a copy of the GNU General Public License
--  along with this program.  If not, see <http://www.gnu.org/licenses/>.

with Crypto_Core_Types; use Crypto_Core_Types;
with Crypto_Types; use Crypto_Types;

use Crypto_Types.Crypto_Utils_u8;

package AES_Spec is

   subtype Key_128_T is Block_128_Bit;
   subtype Key_192_T is Block_192_Bit;
   subtype Key_256_T is Block_256_Bit;

   type Context_128_T is private;
   type Context_192_T is private;
   type Context_256_T is private;

   subtype Block_T is Block_128_Bit;

   procedure Initialize(Context : out Context_128_T; Key : in Key_128_T);
   procedure Encrypt(Context : in Context_128_T; Block: in out Block_T);
   procedure Decrypt(Context : in Context_128_T; Block: in out Block_T);


   procedure Initialize(Context : out Context_192_T; Key : in Key_192_T);
   procedure Encrypt(Context : in Context_192_T; Block: in out Block_T);
   procedure Decrypt(Context : in Context_192_T; Block: in out Block_T);

   procedure Initialize(Context : out Context_256_T; Key : in Key_256_T);
   procedure Encrypt(Context : in Context_256_T; Block: in out Block_T);
   procedure Decrypt(Context : in Context_256_T; Block: in out Block_T);

private

   subtype RoundKey_T is Block_128_Bit;
   type RoundKeys_T is Array (Integer range <>) of RoundKey_T;

   subtype Num_RoundKeys_T is Integer range 11 .. 15;

   type Context_T(Num_RoundKeys : Num_RoundKeys_T := 15) is record
      RoundKeys : RoundKeys_T(1 .. Num_RoundKeys);
   end record;

   type Context_128_T is new Context_T(11);
   type Context_192_T is new Context_T(13);
   type Context_256_T is new Context_T(15);

   Nb : constant Integer := 4;
   polynom : constant u8 := 16#1B#;
   function gf256mul(a, b : u8) return u8;

   generic
      type T_In(<>) is new u8_Array;
      type T_Out(<>) is new Context_T;
   procedure Initialize_Generic(Key : T_In; Context : out T_Out);

end AES_Spec;
