From a65d41bf9319211b7c880689d560949c14e1c5bc Mon Sep 17 00:00:00 2001
From: tmeissner <programming@goodcleanfun.de>
Date: Sun, 22 Mar 2015 23:39:09 +0100
Subject: [PATCH] add verilog version of CBCMAC with DES algorithm

---
 cbcmac_des/rtl/verilog/cbcmac_des.v | 89 +++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 cbcmac_des/rtl/verilog/cbcmac_des.v

diff --git a/cbcmac_des/rtl/verilog/cbcmac_des.v b/cbcmac_des/rtl/verilog/cbcmac_des.v
new file mode 100644
index 0000000..398923e
--- /dev/null
+++ b/cbcmac_des/rtl/verilog/cbcmac_des.v
@@ -0,0 +1,89 @@
+// ======================================================================
+// CBC-MAC-DES
+// Copyright (C) 2015 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
+// ======================================================================
+
+
+`timescale 1ns/1ps
+
+
+module cbcmac_des (
+  input         reset_i,
+  input         clk_i,
+  input         start_i,
+  input  [0:63] key_i,
+  input  [0:63] data_i,
+  input         valid_i,
+  output        accept_o,
+  output [0:63] data_o,
+  output        valid_o,
+  input         accept_i
+);
+
+  // CBCMAC must have fix IV for security reasons
+  reg  [0:63] iv = 0;
+
+  reg  [0:63] key;
+  wire [0:63] des_key;
+  wire [0:63] des_datain;
+  reg  [0:63] des_dataout_d;
+
+
+  assign des_datain = start_i ? iv ^ data_i : des_dataout_d ^ data_i;
+  assign des_key    = start_i ? key_i : key;
+
+
+  // input register
+  always @(posedge clk_i, negedge reset_i) begin
+    if (~reset_i) begin
+      key <= 0;
+    end
+    else begin
+      if (valid_i && accept_o && start_i) begin
+        key <= key_i;
+      end
+    end
+  end
+
+
+  // output register
+  always @(posedge clk_i, negedge reset_i) begin
+    if (~reset_i) begin
+      des_dataout_d <= 0;
+    end
+    else begin
+      if (valid_o) begin
+        des_dataout_d <= data_o;
+      end
+    end
+  end
+
+
+  // des instance
+  des i_des (
+    .reset_i(reset_i),
+    .clk_i(clk_i),
+    .mode_i(1'b0),
+    .key_i(des_key),
+    .data_i(des_datain),
+    .valid_i(valid_i),
+    .data_o(data_o),
+    .valid_o(valid_o)
+  );
+
+
+endmodule
\ No newline at end of file