-------------------------------------------------------------------------------
-- CIPHER.lnt -- 1.20 -- 2024/10/23 06:58:05 -- (C) Wendelin Serwe
-------------------------------------------------------------------------------

module CIPHER (CHANNELS, S_BOX_FUNCTIONS, PERMUTATION_FUNCTIONS) is

-- processes implementing the cipher function according to Fig. 2 of [DES]

-------------------------------------------------------------------------------
-- CIPHER computes "F (R, K) = P (Si (E (R) + K))"

process CIPHER [K: C48, R, PX: C32] is
   hide ER: C48,
        IS1, IS2, IS3, IS4, IS5, IS6, IS7, IS8: C6,
        SO1, SO2, SO3, SO4, SO5, SO6, SO7, SO8: C4
   in
      par
         ER ->
            E [R, ER]
      ||
         ER, IS1, IS2, IS3, IS4, IS5, IS6, IS7, IS8 ->
            XOR_48 [ER, K, IS1, IS2, IS3, IS4, IS5, IS6, IS7, IS8]
      ||
         IS1, IS2, IS3, IS4, IS5, IS6, IS7, IS8,
         SO1, SO2, SO3, SO4, SO5, SO6, SO7, SO8 ->
            par
               S1 [IS1, SO1]
            ||
               S2 [IS2, SO2]
            ||
               S3 [IS3, SO3]
            ||
               S4 [IS4, SO4]
            ||
               S5 [IS5, SO5]
            ||
               S6 [IS6, SO6]
            ||
               S7 [IS7, SO7]
            ||
               S8 [IS8, SO8]
            end par
      ||
         SO1, SO2, SO3, SO4, SO5, SO6, SO7, SO8 ->
            P [SO1, SO2, SO3, SO4, SO5, SO6, SO7, SO8, PX]
      end par
   end hide
end process

-------------------------------------------------------------------------------
-- E expands a 32-bit word to a 48-bit word using function E

process E [INPUT: C32, OUTPUT: C48] is
   var I32: BIT32 in
      loop
         INPUT (?I32);
         OUTPUT (E(I32))
      end loop
   end var
end process

-------------------------------------------------------------------------------
-- XOR_48 asynchronously reads two 48-bit vectors and output the bitwise sum,
-- splitted into eight 6-bit vectors

process XOR_48 [A, B: C48, R1, R2, R3, R4, R5, R6, R7, R8: C6] is
   var A48, B48, I48: BIT48 in
      loop
         par
            A (?A48)
         ||
            B (?B48)
         end par;
         I48 := XOR (A48, B48);
         par
            R1 (1TO6   (I48))
           ||
            R2 (7TO12  (I48))
           ||
            R3 (13TO18 (I48))
           ||
            R4 (19TO24 (I48))
           ||
            R5 (25TO30 (I48))
           ||
            R6 (31TO36 (I48))
           ||
            R7 (37TO42 (I48))
           ||
            R8 (43TO48 (I48))
         end par
      end loop
   end var
end process

-------------------------------------------------------------------------------

process S1 [INPUT: C6, OUTPUT: C4] is
   var I6: BIT6 in
      loop
         INPUT (?I6);
         OUTPUT (NAT_TO_BIT4 (S1 () [GET_ROW (I6)] [GET_COLUMN (I6)]))
      end loop
   end var
end process

-------------------------------------------------------------------------------

process S2 [INPUT: C6, OUTPUT: C4] is
   var I6: BIT6 in
      loop
         INPUT (?I6);
         OUTPUT (NAT_TO_BIT4 (S2 () [GET_ROW (I6)] [GET_COLUMN (I6)]))
      end loop
   end var
end process

-------------------------------------------------------------------------------

process S3 [INPUT: C6, OUTPUT: C4] is
   var I6: BIT6 in
      loop
         INPUT (?I6);
         OUTPUT (NAT_TO_BIT4 (S3 () [GET_ROW (I6)] [GET_COLUMN (I6)]))
      end loop
   end var
end process

-------------------------------------------------------------------------------

process S4 [INPUT: C6, OUTPUT: C4] is
   var I6: BIT6 in
      loop
         INPUT (?I6);
         OUTPUT (NAT_TO_BIT4 (S4 () [GET_ROW (I6)] [GET_COLUMN (I6)]))
      end loop
   end var
end process

-------------------------------------------------------------------------------

process S5 [INPUT: C6, OUTPUT: C4] is
   var I6: BIT6 in
      loop
         INPUT (?I6);
         OUTPUT (NAT_TO_BIT4 (S5 () [GET_ROW (I6)] [GET_COLUMN (I6)]))
      end loop
   end var
end process

-------------------------------------------------------------------------------

process S6 [INPUT: C6, OUTPUT: C4] is
   var I6: BIT6 in
      loop
         INPUT (?I6);
         OUTPUT (NAT_TO_BIT4 (S6 () [GET_ROW (I6)] [GET_COLUMN (I6)]))
      end loop
   end var
end process

-------------------------------------------------------------------------------

process S7 [INPUT: C6, OUTPUT: C4] is
   var I6: BIT6 in
      loop
         INPUT (?I6);
         OUTPUT (NAT_TO_BIT4 (S7 () [GET_ROW (I6)] [GET_COLUMN (I6)]))
      end loop
   end var
end process

-------------------------------------------------------------------------------

process S8 [INPUT: C6, OUTPUT: C4] is
   var I6: BIT6 in
      loop
         INPUT (?I6);
         OUTPUT (NAT_TO_BIT4 (S8 () [GET_ROW (I6)] [GET_COLUMN (I6)]))
      end loop
   end var
end process

-------------------------------------------------------------------------------
-- P collects the results of the eight processes S_BOX_i (on INi) and outputs
-- them in a single transition exit; the permutation P is applied in a second
-- step when outputting the result on OUTPUT.

process P [IN1, IN2, IN3, IN4, IN5, IN6, IN7, IN8: C4, OUTPUT: C32] is
   var I1, I2, I3, I4, I5, I6, I7, I8: BIT4 in
      loop
         par
            IN1 (?I1)
         ||
            IN2 (?I2)
         ||
            IN3 (?I3)
         ||
            IN4 (?I4)
         ||
            IN5 (?I5)
         ||
            IN6 (?I6)
         ||
            IN7 (?I7)
         ||
            IN8 (?I8)
         end par;
         OUTPUT (P (MK_32 (I1, I2, I3, I4, I5, I6, I7, I8)))
      end loop
   end var
end process

end module