rc5_inv.vhd

不带state machine的decryption of rc5

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;   -- we will use CONV_INTEGER

ENTITY rc5_inv_enc IS
    PORT
    (
	clr	: IN STD_LOGIC;  -- Asynchronous reset
	clk	: IN STD_LOGIC;  -- Clock signal
	din	: IN STD_LOGIC_VECTOR(63 DOWNTO 0);  -- 64-bit input
	dout	: OUT STD_LOGIC_VECTOR(63 DOWNTO 0) -- 64-bit output
     );
END rc5_inv_enc;

ARCHITECTURE rtl OF rc5_inv_enc IS
  --round counter
  SIGNAL i_cnt: STD_LOGIC_VECTOR(3 DOWNTO 0);  
  SIGNAL ab_xor: STD_LOGIC_VECTOR(31 DOWNTO 0);
  SIGNAL a_rot: STD_LOGIC_VECTOR(31 DOWNTO 0);
  SIGNAL a: STD_LOGIC_VECTOR(31 DOWNTO 0);
  --register to store value A
  SIGNAL a_reg: STD_LOGIC_VECTOR(31 DOWNTO 0); 
  SIGNAL ba_xor: STD_LOGIC_VECTOR(31 DOWNTO 0);
  SIGNAL b_rot: STD_LOGIC_VECTOR(31 DOWNTO 0);
  SIGNAL b: STD_LOGIC_VECTOR(31 DOWNTO 0);
  --register to store value B
  SIGNAL b_reg: STD_LOGIC_VECTOR(31 DOWNTO 0); 

TYPE rom IS ARRAY (0 TO 25) OF STD_LOGIC_VECTOR(31 DOWNTO 0); 

CONSTANT skey: rom:=rom'(
X"9BBBD8C8",X"1A37F7FB",X"46F8E8C5",X"460C6085",X"70F83B8A", X"284B8303",X"513E1454",X"F621ED22",X"3125065D",X"11A83A5D",
X"D427686B",X"713AD82D",X"4B792F99",X"2799A4DD",X"A7901C49",
X"DEDE871A",X"36C03196",X"A7EFC249",X"61A78BB8",X"3B0A1D2B",
X"4DBFCA76",X"AE162167",X"30D76B0A", X"43192304", X"F6CC1431", X"65046380"); 

BEGIN
   -- B = ((B - S[2譱 +1]) >>> A) xor A;
  ab_xor <= b - skey(CONV_INTEGER(i_cnt & '1'));
   WITH a(4 DOWNTO 0) SELECT
      b_rot<=ab_xor(0) & ab_xor(31 DOWNTO 1) WHEN "00001",
     	ab_xor(1 DOWNTO 0) & ab_xor(31 DOWNTO 2) WHEN "00010",
	ab_xor(2 DOWNTO 0) & ab_xor(31 DOWNTO 3) WHEN "00011",
	ab_xor(3 DOWNTO 0) & ab_xor(31 DOWNTO 4) WHEN "00100",
	ab_xor(4 DOWNTO 0) & ab_xor(31 DOWNTO 5) WHEN "00101",
	ab_xor(5 DOWNTO 0) & ab_xor(31 DOWNTO 6) WHEN "00110",
	ab_xor(6 DOWNTO 0) & ab_xor(31 DOWNTO 7) WHEN "00111",
	ab_xor(7 DOWNTO 0) & ab_xor(31 DOWNTO 8) WHEN "01000",
	ab_xor(8 DOWNTO 0) & ab_xor(31 DOWNTO 9) WHEN "01001",
	ab_xor(9 DOWNTO 0) & ab_xor(31 DOWNTO 10) WHEN "01010",
	ab_xor(10 DOWNTO 0) & ab_xor(31 DOWNTO 11) WHEN "01011",
	ab_xor(11 DOWNTO 0) & ab_xor(31 DOWNTO 12) WHEN "01100",
	ab_xor(12 DOWNTO 0) & ab_xor(31 DOWNTO 13) WHEN "01101",
	ab_xor(13 DOWNTO 0) & ab_xor(31 DOWNTO 14) WHEN "01110",
	ab_xor(14 DOWNTO 0) & ab_xor(31 DOWNTO 15) WHEN "01111",
	ab_xor(15 DOWNTO 0) & ab_xor(31 DOWNTO 16) WHEN "10000",
	ab_xor(16 DOWNTO 0) & ab_xor(31 DOWNTO 17) WHEN "10001",
	ab_xor(17 DOWNTO 0) & ab_xor(31 DOWNTO 18) WHEN "10010",
	ab_xor(18 DOWNTO 0) & ab_xor(31 DOWNTO 19) WHEN "10011",
	ab_xor(19 DOWNTO 0) & ab_xor(31 DOWNTO 20) WHEN "10100",
	ab_xor(20 DOWNTO 0) & ab_xor(31 DOWNTO 21) WHEN "10101",
	ab_xor(21 DOWNTO 0) & ab_xor(31 DOWNTO 22) WHEN "10110",
	ab_xor(22 DOWNTO 0) & ab_xor(31 DOWNTO 23) WHEN "10111",
	ab_xor(23 DOWNTO 0) & ab_xor(31 DOWNTO 24) WHEN "11000",
	ab_xor(24 DOWNTO 0) & ab_xor(31 DOWNTO 25) WHEN "11001",
	ab_xor(25 DOWNTO 0) & ab_xor(31 DOWNTO 26) WHEN "11010",
	ab_xor(26 DOWNTO 0) & ab_xor(31 DOWNTO 27) WHEN "11011",
	ab_xor(27 DOWNTO 0) & ab_xor(31 DOWNTO 28) WHEN "11100",
	ab_xor(28 DOWNTO 0) & ab_xor(31 DOWNTO 29) WHEN "11101",
	ab_xor(29 DOWNTO 0) & ab_xor(31 DOWNTO 30) WHEN "11110",
	ab_xor(30 DOWNTO 0) & ab_xor(31) WHEN "11111",
	ab_xor WHEN OTHERS;
  b_reg <= b_rot XOR a;
 
--A = ((A - S[2譱]) >>> B) xor B;
  ba_xor <= a - skey(CONV_INTEGER(i_cnt & '0'));
  WITH b_reg(4 DOWNTO 0) SELECT
    a_rot<=ba_xor(0) & ba_xor(31 DOWNTO 1) WHEN "00001",
                   ba_xor(1 DOWNTO 0) & ba_xor(31 DOWNTO 2) WHEN "00010",
	ba_xor(2 DOWNTO 0) & ba_xor(31 DOWNTO 3) WHEN "00011",
	ba_xor(3 DOWNTO 0) & ba_xor(31 DOWNTO 4) WHEN "00100",
	ba_xor(4 DOWNTO 0) & ba_xor(31 DOWNTO 5) WHEN "00101",
	ba_xor(5 DOWNTO 0) & ba_xor(31 DOWNTO 6) WHEN "00110",
	ba_xor(6 DOWNTO 0) & ba_xor(31 DOWNTO 7) WHEN "00111",
	ba_xor(7 DOWNTO 0) & ba_xor(31 DOWNTO 8) WHEN "01000",
	ba_xor(8 DOWNTO 0) & ba_xor(31 DOWNTO 9) WHEN "01001",
	ba_xor(9 DOWNTO 0) & ba_xor(31 DOWNTO 10) WHEN "01010",
	ba_xor(10 DOWNTO 0) & ba_xor(31 DOWNTO 11) WHEN "01011",
	ba_xor(11 DOWNTO 0) & ba_xor(31 DOWNTO 12) WHEN "01100",
	ba_xor(12 DOWNTO 0) & ba_xor(31 DOWNTO 13) WHEN "01101",
	ba_xor(13 DOWNTO 0) & ba_xor(31 DOWNTO 14) WHEN "01110",
	ba_xor(14 DOWNTO 0) & ba_xor(31 DOWNTO 15) WHEN "01111",
	ba_xor(15 DOWNTO 0) & ba_xor(31 DOWNTO 16) WHEN "10000",
	ba_xor(16 DOWNTO 0) & ba_xor(31 DOWNTO 17) WHEN "10001",
	ba_xor(17 DOWNTO 0) & ba_xor(31 DOWNTO 18) WHEN "10010",
	ba_xor(18 DOWNTO 0) & ba_xor(31 DOWNTO 19) WHEN "10011",
	ba_xor(19 DOWNTO 0) & ba_xor(31 DOWNTO 20) WHEN "10100",
	ba_xor(20 DOWNTO 0) & ba_xor(31 DOWNTO 21) WHEN "10101",
	ba_xor(21 DOWNTO 0) & ba_xor(31 DOWNTO 22) WHEN "10110",
	ba_xor(22 DOWNTO 0) & ba_xor(31 DOWNTO 23) WHEN "10111",
	ba_xor(23 DOWNTO 0) & ba_xor(31 DOWNTO 24) WHEN "11000",
	ba_xor(24 DOWNTO 0) & ba_xor(31 DOWNTO 25) WHEN "11001",
	ba_xor(25 DOWNTO 0) & ba_xor(31 DOWNTO 26) WHEN "11010",
	ba_xor(26 DOWNTO 0) & ba_xor(31 DOWNTO 27) WHEN "11011",
	ba_xor(27 DOWNTO 0) & ba_xor(31 DOWNTO 28) WHEN "11100",
	ba_xor(28 DOWNTO 0) & ba_xor(31 DOWNTO 29) WHEN "11101",
	ba_xor(29 DOWNTO 0) & ba_xor(31 DOWNTO 30) WHEN "11110",
	ba_xor(30 DOWNTO 0) & ba_xor(31) WHEN "11111",
	ba_xor WHEN OTHERS;
   a_reg <= a_rot XOR b_reg;
-- Register A
PROCESS(clr, clk)  BEGIN
  IF(clr='0') THEN a <= din(63 DOWNTO 32);
  ELSIF(clk'EVENT AND clk='1') THEN a<=a_reg;
  END IF;
END PROCESS;

-- Register B
PROCESS(clr, clk)  BEGIN
  IF(clr='0') THEN b<=din(31 DOWNTO 0);
  ELSIF(clk'EVENT AND clk='1') THEN b<=b_reg;
  END IF;
END PROCESS;   

PROCESS (clr, clk)  BEGIN
  IF(clr='0') THEN
      i_cnt<="1100";
   ELSIF(clk'EVENT AND clk='1') THEN
       IF(i_cnt="0001") THEN
         i_cnt<="1100";
       ELSE
         i_cnt<=i_cnt-'1';
       END IF;
    END IF;
END PROCESS;

dout<= a_reg & b_reg;

END rtl;