Add CTR-AES VHDL design

* CTR-AES design with configurable Nonce length (64-96)
* Max. secure frame length is 2**(128-len(nonce))-1

ctraes/rtl/vhdl/ctraes.vhd

@@ -0,0 +1,121 @@
+-- ======================================================================
+-- CTR-AES
+-- Copyright (C) 2020 Torsten Meissner
+-------------------------------------------------------------------------
+-- This program is free software; you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation; either version 2 of the License, or
+-- (at your option) any later version.
+
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+
+-- You should have received a copy of the GNU General Public License
+-- along with this program; if not, write to the Free Software
+-- Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+-- ======================================================================
+
+
+library ieee;
+  use ieee.std_logic_1164.all;
+  use ieee.numeric_std.all;
+
+use work.aes_pkg.all;
+
+
+
+entity ctraes is
+  generic (
+    NONCE_WIDTH : natural range 64 to 96 := 96
+  );
+  port (
+    reset_i     : in  std_logic;                             -- low active async reset
+    clk_i       : in  std_logic;                             -- clock
+    start_i     : in  std_logic;                             -- start ctr
+    nonce_i     : in  std_logic_vector(0 to NONCE_WIDTH-1);  -- nonce
+    key_i       : in  std_logic_vector(0 to 127);            -- key input
+    data_i      : in  std_logic_vector(0 to 127);            -- data input
+    valid_i     : in  std_logic;                             -- input key/data valid flag
+    accept_o    : out std_logic;                             -- input accept
+    data_o      : out std_logic_vector(0 tO 127);            -- data output
+    valid_o     : out std_logic;                             -- output data valid flag
+    accept_i    : in  std_logic                              -- output accept
+  );
+end entity ctraes;
+
+
+
+architecture rtl of ctraes is
+
+
+  signal s_aes_datain    : std_logic_vector(data_i'range);
+  signal s_aes_dataout   : std_logic_vector(data_o'range);
+  signal s_aes_key       : std_logic_vector(key_i'range);
+  signal s_key           : std_logic_vector(key_i'range);
+  signal s_nonce         : std_logic_vector(nonce_i'range);
+  signal s_data_in       : std_logic_vector(data_i'range);
+  signal s_counter       : unsigned(0 to 127-NONCE_WIDTH);
+
+
+begin
+
+
+  s_aes_key    <= key_i when start_i = '1' else s_key;
+  s_aes_datain <= nonce_i & (s_counter'range => '0') when start_i = '1' else
+                  s_nonce & std_logic_vector(s_counter);
+
+  data_o   <= s_aes_dataout xor s_data_in;
+
+
+  inputreg : process (clk_i, reset_i) is
+  begin
+    if (reset_i = '0') then
+      s_key     <= (others => '0');
+      s_nonce   <= (others => '0');
+      s_data_in <= (others => '0');
+    elsif (rising_edge(clk_i)) then
+      if (valid_i = '1' and accept_o = '1') then
+        s_data_in <= data_i;
+        if (start_i = '1') then
+          s_key   <= key_i;
+          s_nonce <= nonce_i;
+        end if;
+      end if;
+    end if;
+  end process inputreg;
+
+
+  counterreg : process (clk_i, reset_i) is
+  begin
+    if (reset_i = '0') then
+      s_counter <= (others => '0');
+    elsif (rising_edge(clk_i)) then
+      if (valid_i = '1' and accept_o = '1' and start_i = '1') then
+        s_counter <= (others => '0');
+      elsif (valid_o = '1' and accept_i = '1') then
+        s_counter <= s_counter + 1;
+      end if;
+    end if;
+  end process counterreg;
+
+
+  i_aes : aes_enc
+    generic map (
+      design_type => "ITER"
+    )
+    port map (
+      reset_i  => reset_i,
+      clk_i    => clk_i,
+      key_i    => s_aes_key,
+      data_i   => s_aes_datain,
+      valid_i  => valid_i,
+      accept_o => accept_o,
+      data_o   => s_aes_dataout,
+      valid_o  => valid_o,
+      accept_i => accept_i
+    );
+
+
+end architecture rtl;