Subversion Repositories tiny_encryption_algorithm

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

use ieee.std_logic_unsigned.all;

entity tea64 is

   port(

      key : in std_logic_vector(127 downto 0);

      text : in std_logic_vector(63 downto 0);

      cipher : out std_logic_vector(63 downto 0)

      );

end tea64;

architecture Behavioral of tea64 is

   type teaA is array (64 downto 0) of std_logic_vector(31 downto 0);

   signal v0,v1,sum,feistelOut,feistelKey0,feistelKey1 : teaA;

   signal k0,k1,k2,k3 : std_logic_vector(31 downto 0);

begin

   sum(0)  <= x"9e3779b9";

   k0 <= key(31  downto  0);

   k1 <= key(63  downto 32);

   k2 <= key(95  downto 64);

   k3 <= key(127 downto 96);

   v0(0) <= text(31  downto  0);

   v1(0) <= text(63  downto 32);

   general_pipe: for i in 1 to 64 generate

      v1(i) <= v0(i-1) + feistelOut(i);

      v0(i) <= v1(i-1);

   end generate;

   feistel_pipe_odd: for j in 0 to 31 generate

      sum(2*j+1) <= sum(2*j);

      feistelOut(2*j+1) <= (v1(2*j) + sum(2*j)) xor ((v1(2*j)(27 downto 0) & "0000") + k0) xor (("00000" & v1(2*j)(31 downto 5)) + k1);

   end generate;

   feistel_pipe_even: for k in 1 to 32 generate

      sum(2*k) <= sum(2*k-1) + x"9e3779b9";

      feistelOut(2*k) <= (v1(2*k-1) + sum(2*k-1)) xor ((v1(2*k-1)(27 downto 0) & "0000") + k2) xor (("00000" & v1(2*k-1)(31 downto 5)) + k3);

   end generate;

   cipher <= v1(64) & v0(64);

end Behavioral;