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-- cipher module, as described in: "FIPS 197, 5.1 Cipher"
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library aes_lib;
use aes_lib.aes_pkg.all;
entity cipher is
generic (
G_KEY_WORDS : integer := 4
);
port (
isl_clk : in std_logic;
isl_valid : in std_logic;
ia_data : in st_state;
ia_key : in t_key(0 to G_KEY_WORDS - 1);
oa_data : out st_state;
osl_valid : out std_logic
);
end entity cipher;
architecture rtl of cipher is
-- states
signal slv_stage : std_logic_vector(1 to 2) := (others => '0');
signal sl_next_round : std_logic := '0';
-- data container
-- data format in key expansion: words are rows
-- data format in cipher: words are columns
-- conversion: transpose matrix
signal a_data_in : st_state;
signal a_data_added : st_state;
signal a_data_srows : st_state;
-- keys
signal a_round_keys : st_state;
signal int_round_cnt : integer range 0 to 13 := 0;
begin
sl_next_round <= slv_stage(2);
proc_key_expansion : process (isl_clk) is
variable v_new_col : integer range 0 to C_STATE_COLS - 1;
variable v_data_sbox : st_state;
variable v_data_mcols : st_state;
begin
if (rising_edge(isl_clk)) then
slv_stage <= (isl_valid or sl_next_round) & slv_stage(1);
-- substitute bytes and shift rows
if (slv_stage(1) = '1') then
for row in 0 to C_STATE_ROWS - 1 loop
for col in 0 to 0 loop --C_STATE_COLS - 1 loop
-- substitute bytes
-- v_data_sbox(row, col) := C_SBOX(to_integer(a_data_added(row, col)));
v_data_sbox(row, col) := a_data_added(row, col);
-- shift rows
-- avoid modulo by using unsigned overflow
v_new_col := to_integer(to_unsigned(col, 1) - row);
a_data_srows(row, v_new_col) <= v_data_sbox(row, col);
end loop;
end loop;
end if;
-- mix columns and add key
if (slv_stage(2) = '1') then
a_data_added <= mix_columns(a_data_srows);
end if;
end if;
end process proc_key_expansion;
oa_data <= a_data_added;
osl_valid <= '0';
end architecture rtl;
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