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-- Implementation of the Lilliput-TBC tweakable block cipher by the
-- Lilliput-AE team, hereby denoted as "the implementer".
--
-- For more information, feedback or questions, refer to our website:
-- https://paclido.fr/lilliput-ae
--
-- To the extent possible under law, the implementer has waived all copyright
-- and related or neighboring rights to the source code in this file.
-- http://creativecommons.org/publicdomain/zero/1.0/
library IEEE;
library work;
use IEEE.std_logic_1164.all;
use work.crypt_pack.all;
entity sbox is
port(
sbox_i : in bit8;
sbox_o : out bit8
);
end sbox;
architecture sbox_arch of sbox is
signal a,b : std_logic_vector(3 downto 0);
signal ax,ay,at,az : std_logic;
signal aa,ab : std_logic;
signal bx,bz : std_logic;
signal bt,by : std_logic;
signal cx,cy,ct : std_logic;
signal ca,cb,cz : std_logic;
begin
aa <= sbox_i(3) xor sbox_i(1);
ab <= sbox_i(0) xor (sbox_i(2) and sbox_i(1));
az <= sbox_i(2) xor ab;
ax <= aa and (sbox_i(2) xor ab);
ay <= sbox_i(3) and ab;
at <= (az xor sbox_i(3)) and (sbox_i(2) xor aa);
a <= ax & ay & az & at xor sbox_i(7 downto 4);
bx <= a(0) xor (a(3) and by);
bz <= a(3) xor (bt and by);
by <= a(2) xor (a(0) and a(1));
bt <= a(1) xor (a(3) and a(0));
b <= bx & by & bz & bt xor sbox_i(3 downto 0);
ca <= b(3) xor b(1);
cb <= not (b(0) xor (b(2) and b(1)));
cx <= ca and cz;
cz <= b(2) xor cb;
cy <= b(3) and cb;
ct <= (cz xor b(3)) and (b(2) xor ca);
sbox_o (7 downto 4) <= cx & cy & cz & ct xor a;
sbox_o (3 downto 0) <= b;
end sbox_arch;
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