cryptography ip-cores in vhdl / verilog
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// ======================================================================
// CBC-DES encryption/decryption
// algorithm according to FIPS 46-3 specification
// Copyright (C) 2013 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:the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
// ======================================================================
`timescale 1ns/1ps
module cbcdes
(
input reset_i, // async reset
input clk_i, // clock
input start_i, // start cbc
input mode_i, // des-mode: 0 = encrypt, 1 = decrypt
input [0:63] key_i, // key input
input [0:63] iv_i, // iv input
input [0:63] data_i, // data input
input valid_i, // input key/data valid flag
output reg ready_o, // ready to encrypt/decrypt
output reg [0:63] data_o, // data output
output valid_o // output data valid flag
);
reg mode;
wire des_mode;
reg start;
reg [0:63] key;
wire [0:63] des_key;
reg [0:63] iv;
reg [0:63] datain;
reg [0:63] datain_d;
reg [0:63] des_datain;
wire validin;
wire [0:63] des_dataout;
reg reset;
reg [0:63] dataout;
assign des_key = (start_i) ? key_i : key;
assign des_mode = (start_i) ? mode_i : mode;
assign validin = valid_i & ready_o;
always @(*) begin
if (~mode_i && start_i) begin
des_datain = iv_i ^ data_i;
end
else if (~mode && ~start_i) begin
des_datain = dataout ^ data_i;
end
else begin
des_datain = data_i;
end
end
always @(*) begin
if (mode && start) begin
data_o = iv ^ des_dataout;
end
else if (mode && ~start) begin
data_o = datain_d ^ des_dataout;
end
else begin
data_o = des_dataout;
end
end
// input register
always @(posedge clk_i, negedge reset_i) begin
if (~reset_i) begin
reset <= 0;
mode <= 0;
start <= 0;
key <= 0;
iv <= 0;
datain <= 0;
datain_d <= 0;
end
else begin
reset <= reset_i;
if (valid_i && ready_o) begin
start <= start_i;
datain <= data_i;
datain_d <= datain;
end
else if (valid_i && ready_o && start_i) begin
mode <= mode_i;
key <= key_i;
iv <= iv_i;
end
end
end
// output register
always @(posedge clk_i, negedge reset_i) begin
if (~reset_i) begin
ready_o <= 0;
dataout <= 0;
end
else begin
if (valid_i && ready_o) begin
ready_o <= 0;
end
else if (valid_o || (reset_i && ~reset)) begin
ready_o <= 1;
dataout <= des_dataout;
end
end
end
// des instance
des i_des (
.reset_i(reset),
.clk_i(clk_i),
.mode_i(des_mode),
.key_i(des_key),
.data_i(des_datain),
.valid_i(validin),
.data_o(des_dataout),
.valid_o(valid_o)
);
endmodule