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[/] [apbtoaes128/] [trunk/] [rtl/] [key_expander.v] - Rev 12
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////////////////////////////////////////////////////////////////// //// //// //// AES CORE BLOCK //// //// //// //// This file is part of the APB to I2C project //// //// http://www.opencores.org/cores/apbi2c/ //// //// //// //// Description //// //// Implementation of APB IP core according to //// //// aes128_spec IP core specification document. //// //// //// //// To Do: Things are right here but always all block can suffer changes //// //// //// //// //// //// Author(s): - Felipe Fernandes Da Costa, fefe2560@gmail.com //// Julio Cesar //// ///////////////////////////////////////////////////////////////// //// //// //// Copyright (C) 2009 Authors and OPENCORES.ORG //// //// //// //// This source file may be used and distributed without //// //// restriction provided that this copyright statement is not //// //// removed from the file and that any derivative work contains //// the original copyright notice and the associated disclaimer. //// //// //// This source file is free software; you can redistribute it //// //// and/or modify it under the terms of the GNU Lesser General //// //// Public License as published by the Free Software Foundation; //// either version 2.1 of the License, or (at your option) any //// //// later version. //// //// //// //// This source 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 Lesser General Public License for more //// details. //// //// //// //// You should have received a copy of the GNU Lesser General //// //// Public License along with this source; if not, download it //// //// from http://www.opencores.org/lgpl.shtml //// //// /////////////////////////////////////////////////////////////////// module key_expander ( // OUTPUTS output [127:0] key_out, output [ 31:0] g_in, // INPUTS input [ 31:0] g_out, input [127:0] key_in, input [ 3:0] round, input add_w_out, input enc_dec ); localparam integer KEY_WIDTH = 32; localparam integer KEY_NUM = 4; localparam integer WORD = 8; localparam integer ROUNDS = 10; wire [KEY_WIDTH - 1 : 0] key [0 : KEY_NUM - 1]; wire [ WORD - 1 : 0] rot_in[0 : KEY_NUM - 1]; wire [KEY_WIDTH - 1 : 0] g_func; reg [ WORD - 1 : 0] rc_dir, rc_inv; wire [ WORD - 1 : 0] rc; //===================================================================================== // Key Generation //===================================================================================== generate genvar i; for(i = 0; i < KEY_NUM; i = i + 1) begin assign key[KEY_NUM - 1 - i] = key_in[KEY_WIDTH*(i + 1) - 1 : KEY_WIDTH*i]; end endgenerate //===================================================================================== // Key Out Generation //===================================================================================== generate genvar j; for(j = 0; j < KEY_NUM; j = j + 1) begin if(j == 0) assign key_out[KEY_WIDTH*(KEY_NUM - j) - 1 : KEY_WIDTH*(KEY_NUM - j - 1)] = key[j] ^ g_func; else if(j == 1) assign key_out[KEY_WIDTH*(KEY_NUM - j) - 1 : KEY_WIDTH*(KEY_NUM - j - 1)] = (add_w_out) ? key[j] ^ key[j - 1] ^ g_func : key[j] ^ key[j - 1]; else assign key_out[KEY_WIDTH*(KEY_NUM - j) - 1 : KEY_WIDTH*(KEY_NUM - j - 1)] = key[j] ^ key[j - 1]; end endgenerate //===================================================================================== // G Function Input Generation //===================================================================================== generate genvar k; for(k = 0; k < KEY_NUM; k = k + 1) assign rot_in[k] = (enc_dec) ? key[KEY_NUM - 1][WORD*(k + 1) - 1 : WORD*k] : key[KEY_NUM - 1][WORD*(k + 1) - 1 : WORD*k] ^ key[KEY_NUM - 2][WORD*(k + 1) - 1 : WORD*k]; endgenerate generate genvar l; for(l = 0; l < KEY_NUM; l = l + 1) assign g_in[WORD*(l + 1) - 1 : WORD*l] = rot_in[(KEY_NUM + l - 1)%KEY_NUM]; endgenerate //===================================================================================== // G Functin Output Processsing //===================================================================================== assign g_func = {g_out[KEY_WIDTH - 1 : KEY_WIDTH - WORD] ^ rc, g_out[KEY_WIDTH - WORD - 1 : 0]}; assign rc = (enc_dec) ? rc_dir : rc_inv; always @(*) begin: RC_DIR integer i; for(i = 0; i < ROUNDS; i = i + 1) if(round == 8) rc_dir = 8'h1b; else if(round == 9) rc_dir = 8'h36; else rc_dir = 8'h01 << round; end always @(*) begin: RC_INV integer i; for(i = 0; i < ROUNDS; i = i + 1) if(round == 1) rc_inv = 8'h1b; else if(round == 0) rc_inv = 8'h36; else rc_inv = 8'h80 >> (round - 2); end endmodule
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