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eucrypt_ch6_kecca...    1  -- S.MG implementation of Keccak-f permutations
eucrypt_ch6_kecca...    2 
eucrypt_ch6_kecca...    3  -- (Based on The Keccak Reference, Version 3.0, January 14, 2011, by
eucrypt_ch6_kecca...    4  --   Guido Bertoni, Joan Daemen, Michael Peeters and Gilles Van Assche)
eucrypt_ch6_kecca...    5 
eucrypt_ch6_kecca...    6  -- S.MG, 2018
eucrypt_ch6_kecca...    7 
eucrypt_ch6_kecca...    8 package SMG_Keccak is
eucrypt_ch6_kecca...    9 	pragma Pure(SMG_Keccak);  --stateless, no side effects -> can cache calls
eucrypt_ch6_kecca...   10 
eucrypt_ch6_kecca...   11   --knobs (can change as per keccak design but fixed here for S.MG purposes)--
eucrypt_ch6_kecca...   12   Keccak_L: constant := 6;  --gives keccak z (word) dimension of 2^6=64 and 
eucrypt_ch6_kecca...   13                             --therefore keccak function 1600 with current 
eucrypt_ch6_kecca...   14                             --constants (5*5*2^6)
eucrypt_ch6_kecca...   15 
eucrypt_ch6_kecca...   16   --constants: dimensions of keccak state and number of rounds
eucrypt_ch6_kecca...   17   XY_Length: constant := 5;
eucrypt_ch6_kecca...   18   Z_Length: constant := 2**Keccak_L;
eucrypt_ch6_kecca...   19   Width: constant := XY_Length * XY_Length * Z_Length;
eucrypt_ch6_kecca...   20   N_Rounds: constant := 12 + 2*Keccak_L;
eucrypt_ch6_kecca...   21 
eucrypt_ch6_kecca...   22   --types
eucrypt_ch6_kecca...   23   type XYCoord is mod XY_Length;
eucrypt_ch6_kecca...   24   type ZCoord is mod Z_Length;
eucrypt_ch6_kecca...   25   type Round_Index is mod N_Rounds;
eucrypt_ch6_kecca...   26 
eucrypt_ch6_kecca...   27   type ZWord is mod 2**Z_Length;	--"lane" in keccak ref
eucrypt_ch6_kecca...   28   type Plane is array(XYCoord) of ZWord; --a "horizontal slice" of keccak state
eucrypt_ch6_kecca...   29   type State is array(XYCoord, XYCoord) of ZWord; --the full keccak state
eucrypt_ch6_kecca...   30 
eucrypt_ch6_kecca...   31   type Round_Constants is array(Round_Index) of ZWord;  --magic keccak constants
eucrypt_ch6_kecca...   32 
eucrypt_ch6_kecca...   33 private
eucrypt_ch6_kecca...   34   -- these are internals of the keccak implementation, not meant to be directly 
eucrypt_ch6_kecca...   35   --  accessed/used
eucrypt_ch6_kecca...   36 
eucrypt_ch6_kecca...   37   --Keccak magic numbers
eucrypt_ch6_kecca...   38   RC : constant Round_Constants :=
eucrypt_ch6_kecca...   39     (
eucrypt_ch6_kecca...   40      16#0000_0000_0000_0001#,
eucrypt_ch6_kecca...   41      16#0000_0000_0000_8082#,
eucrypt_ch6_kecca...   42      16#8000_0000_0000_808A#,
eucrypt_ch6_kecca...   43      16#8000_0000_8000_8000#,
eucrypt_ch6_kecca...   44      16#0000_0000_0000_808B#,
eucrypt_ch6_kecca...   45      16#0000_0000_8000_0001#,
eucrypt_ch6_kecca...   46      16#8000_0000_8000_8081#,
eucrypt_ch6_kecca...   47      16#8000_0000_0000_8009#,
eucrypt_ch6_kecca...   48      16#0000_0000_0000_008A#,
eucrypt_ch6_kecca...   49      16#0000_0000_0000_0088#,
eucrypt_ch6_kecca...   50      16#0000_0000_8000_8009#,
eucrypt_ch6_kecca...   51      16#0000_0000_8000_000A#,
eucrypt_ch6_kecca...   52      16#0000_0000_8000_808B#,
eucrypt_ch6_kecca...   53      16#8000_0000_0000_008B#,
eucrypt_ch6_kecca...   54      16#8000_0000_0000_8089#,
eucrypt_ch6_kecca...   55      16#8000_0000_0000_8003#,
eucrypt_ch6_kecca...   56      16#8000_0000_0000_8002#,
eucrypt_ch6_kecca...   57      16#8000_0000_0000_0080#,
eucrypt_ch6_kecca...   58      16#0000_0000_0000_800A#,
eucrypt_ch6_kecca...   59      16#8000_0000_8000_000A#,
eucrypt_ch6_kecca...   60      16#8000_0000_8000_8081#,
eucrypt_ch6_kecca...   61      16#8000_0000_0000_8080#,
eucrypt_ch6_kecca...   62      16#0000_0000_8000_0001#,
eucrypt_ch6_kecca...   63      16#8000_0000_8000_8008#
eucrypt_ch6_kecca...   64     );
eucrypt_ch6_kecca...   65 
eucrypt_ch6_kecca...   66   --gnat-specific methods to have bit-ops for modular types
eucrypt_ch6_kecca...   67   function Rotate_Left( Value  : ZWord; 
eucrypt_ch6_kecca...   68 	                      Amount : Natural) 
eucrypt_ch6_kecca...   69 	                      return ZWord;
eucrypt_ch6_kecca...   70 	pragma Import(Intrinsic, Rotate_Left); 
eucrypt_ch6_kecca...   71 
eucrypt_ch6_kecca...   72 	function Shift_Right( Value  : ZWord; 
eucrypt_ch6_kecca...   73                         Amount : Natural) 
eucrypt_ch6_kecca...   74                         return ZWord;
eucrypt_ch6_kecca...   75   pragma Import(Intrinsic, Shift_Right); 
eucrypt_ch6_kecca...   76 
eucrypt_ch6_kecca...   77   --Keccak permutations 
eucrypt_ch6_kecca...   78   function Theta ( Input       : in State) return State;
eucrypt_ch6_kecca...   79   function Rho   ( Input       : in State) return State;
eucrypt_ch6_kecca...   80   function Pi    ( Input       : in State) return State;
eucrypt_ch6_kecca...   81   function Chi   ( Input       : in State) return State;
eucrypt_ch6_kecca...   82   function Iota  ( Round_Const : in ZWord; Input : in State) return State;
eucrypt_ch6_kecca...   83 
eucrypt_ch6_kecca...   84   --Keccak full function with block width currently 1600 (Width constant above)
eucrypt_ch6_kecca...   85   --this simply applies *all* keccak permutations in the correct order and using 
eucrypt_ch6_kecca...   86   -- the keccak magic numbers (round constants) as per keccak reference
eucrypt_ch6_kecca...   87   function Keccak_Function(Input: in State) return State;
eucrypt_ch6_kecca...   88 
eucrypt_ch6_kecca...   89 end SMG_Keccak;