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//////////////////////////////////////////////////////////////////////
////                                                              ////
////  S-Box calculation                                           ////
////                                                              ////
////  This file is part of the SystemC AES                        ////
////                                                              ////
////  Description:                                                ////
////  S-box calculation calculating inverse on gallois field      ////
////                                                              ////
////  Generated automatically using SystemC to Verilog translator ////
////                                                              ////
////  To Do:                                                      ////
////   - done                                                     ////
////                                                              ////
////  Author(s):                                                  ////
////      - Javier Castillo, jcastilo@opencores.org               ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
////                                                              ////
//// Copyright (C) 2000 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                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
//
// CVS Revision History
//
// $Log: not supported by cvs2svn $
// Revision 1.3  2004/08/30 16:23:57  jcastillo
// Indentation corrected
//
// Revision 1.2  2004/07/22 08:51:22  jcastillo
// Added timescale directive
//
// Revision 1.1.1.1  2004/07/05 09:46:23  jcastillo
// First import
//
 
`include "timescale.v"
 
module sbox(clk,reset,data_i,decrypt_i,data_o);
input clk;
input reset;
input [7:0] data_i;
input decrypt_i;
output [7:0] data_o;
 
reg [7:0] data_o;
 
reg [7:0] inva;
reg [3:0] ah;
reg [3:0] al;
reg [3:0] ah2;
reg [3:0] al2;
reg [3:0] alxh;
reg [3:0] alph;
reg [3:0] d;
reg [3:0] ahp;
reg [3:0] alp;
reg [3:0] to_invert;
reg [3:0] next_to_invert;
reg [3:0] ah_reg;
reg [3:0] next_ah_reg;
reg [3:0] next_alph;
 
 
//registers:
always @(posedge clk or negedge reset)
begin
 
  if(!reset)
  begin
 
    to_invert = (0);
    ah_reg = (0);
    alph = (0);	
 
  end
  else
  begin
 
    to_invert = (next_to_invert);
    ah_reg = (next_ah_reg);
    alph = (next_alph);	
 
  end
 
end
 
 
//first_mux:
reg[7:0] first_mux_data_var;
reg[7:0] first_mux_InvInput;
reg[3:0] first_mux_ah_t,first_mux_al_t;
reg first_mux_aA,first_mux_aB,first_mux_aC,first_mux_aD;
 
always @(data_i or decrypt_i)
begin
 
  first_mux_data_var=data_i;
  first_mux_InvInput=first_mux_data_var;
 
  case(decrypt_i)
    1:
     begin
 
       //Apply inverse affine trasformation
       first_mux_aA=first_mux_data_var[0]^first_mux_data_var[5];first_mux_aB=first_mux_data_var[1]^first_mux_data_var[4];
       first_mux_aC=first_mux_data_var[2]^first_mux_data_var[7];first_mux_aD=first_mux_data_var[3]^first_mux_data_var[6];
       first_mux_InvInput[0]=(!first_mux_data_var[5])^first_mux_aC;
       first_mux_InvInput[1]=first_mux_data_var[0]^first_mux_aD;
       first_mux_InvInput[2]=(!first_mux_data_var[7])^first_mux_aB;
       first_mux_InvInput[3]=first_mux_data_var[2]^first_mux_aA;
       first_mux_InvInput[4]=first_mux_data_var[1]^first_mux_aD;
       first_mux_InvInput[5]=first_mux_data_var[4]^first_mux_aC;
       first_mux_InvInput[6]=first_mux_data_var[3]^first_mux_aA;
       first_mux_InvInput[7]=first_mux_data_var[6]^first_mux_aB;
 
     end
 
   default:
     begin
 
       first_mux_InvInput=first_mux_data_var;
 
     end
 
  endcase
 
 
  //Convert elements from GF(2^8) into two elements of GF(2^4^2)
 
  first_mux_aA=first_mux_InvInput[1]^first_mux_InvInput[7];
  first_mux_aB=first_mux_InvInput[5]^first_mux_InvInput[7];
  first_mux_aC=first_mux_InvInput[4]^first_mux_InvInput[6];
 
  first_mux_al_t[0]=first_mux_aC^first_mux_InvInput[0]^first_mux_InvInput[5];
  first_mux_al_t[1]=first_mux_InvInput[1]^first_mux_InvInput[2];
  first_mux_al_t[2]=first_mux_aA;
  first_mux_al_t[3]=first_mux_InvInput[2]^first_mux_InvInput[4];
 
  first_mux_ah_t[0]=first_mux_aC^first_mux_InvInput[5];
  first_mux_ah_t[1]=first_mux_aA^first_mux_aC;
  first_mux_ah_t[2]=first_mux_aB^first_mux_InvInput[2]^first_mux_InvInput[3];
  first_mux_ah_t[3]=first_mux_aB;
 
  al = (first_mux_al_t);
  ah = (first_mux_ah_t);
  next_ah_reg = (first_mux_ah_t);
 
end
//end_mux:
 
 
reg[7:0] end_mux_data_var,end_mux_data_o_var;
reg end_mux_aA,end_mux_aB,end_mux_aC,end_mux_aD;
 
always @(decrypt_i or inva)
begin
 
  //Take the output of the inverter
  end_mux_data_var=inva;
 
  case(decrypt_i)
 
    0:
     begin
       //Apply affine trasformation
 
       end_mux_aA=end_mux_data_var[0]^end_mux_data_var[1];end_mux_aB=end_mux_data_var[2]^end_mux_data_var[3];
       end_mux_aC=end_mux_data_var[4]^end_mux_data_var[5];end_mux_aD=end_mux_data_var[6]^end_mux_data_var[7];
       end_mux_data_o_var[0]=(!end_mux_data_var[0])^end_mux_aC^end_mux_aD;
       end_mux_data_o_var[1]=(!end_mux_data_var[5])^end_mux_aA^end_mux_aD;
       end_mux_data_o_var[2]=end_mux_data_var[2]^end_mux_aA^end_mux_aD;
       end_mux_data_o_var[3]=end_mux_data_var[7]^end_mux_aA^end_mux_aB;
       end_mux_data_o_var[4]=end_mux_data_var[4]^end_mux_aA^end_mux_aB;
       end_mux_data_o_var[5]=(!end_mux_data_var[1])^end_mux_aB^end_mux_aC;
       end_mux_data_o_var[6]=(!end_mux_data_var[6])^end_mux_aB^end_mux_aC;
       end_mux_data_o_var[7]=end_mux_data_var[3]^end_mux_aC^end_mux_aD;
 
       data_o = (end_mux_data_o_var);
     end
 
    default:
     begin
 
       data_o = (end_mux_data_var);
     end
  endcase
 
end
 
 
//inversemap:
reg[3:0] aA,aB;
reg[3:0] inversemap_alp_t,inversemap_ahp_t;
reg[7:0] inversemap_inva_t;
 
always @(alp or ahp)
begin
 
  inversemap_alp_t=alp;
  inversemap_ahp_t=ahp;
 
  aA=inversemap_alp_t[1]^inversemap_ahp_t[3];
  aB=inversemap_ahp_t[0]^inversemap_ahp_t[1];
 
  inversemap_inva_t[0]=inversemap_alp_t[0]^inversemap_ahp_t[0];
  inversemap_inva_t[1]=aB^inversemap_ahp_t[3];
  inversemap_inva_t[2]=aA^aB;
  inversemap_inva_t[3]=aB^inversemap_alp_t[1]^inversemap_ahp_t[2];
  inversemap_inva_t[4]=aA^aB^inversemap_alp_t[3];
  inversemap_inva_t[5]=aB^inversemap_alp_t[2];
  inversemap_inva_t[6]=aA^inversemap_alp_t[2]^inversemap_alp_t[3]^inversemap_ahp_t[0];
  inversemap_inva_t[7]=aB^inversemap_alp_t[2]^inversemap_ahp_t[3];
 
  inva = (inversemap_inva_t);
 
end
 
//mul1:
reg[3:0] mul1_alxh_t;
reg[3:0] mul1_aA,mul1_a;
 
always @(ah or al)
begin
 
  //alxah
  mul1_aA=al[0]^al[3];
  mul1_a=al[2]^al[3];
 
  mul1_alxh_t[0]=(al[0]&ah[0])^(al[3]&ah[1])^(al[2]&ah[2])^(al[1]&ah[3]);
  mul1_alxh_t[1]=(al[1]&ah[0])^(mul1_aA&ah[1])^(mul1_a&ah[2])^((al[1]^al[2])&ah[3]);
  mul1_alxh_t[2]=(al[2]&ah[0])^(al[1]&ah[1])^(mul1_aA&ah[2])^(mul1_a&ah[3]);
  mul1_alxh_t[3]=(al[3]&ah[0])^(al[2]&ah[1])^(al[1]&ah[2])^(mul1_aA&ah[3]);
 
  alxh = (mul1_alxh_t);
 
end
 
 
//mul2:
reg[3:0] mul2_ahp_t;
reg[3:0] mul2_aA,mul2_aB;
 
always @(d or ah_reg)
begin
 
//ahxd
 
  mul2_aA=ah_reg[0]^ah_reg[3];
  mul2_aB=ah_reg[2]^ah_reg[3];
 
  mul2_ahp_t[0]=(ah_reg[0]&d[0])^(ah_reg[3]&d[1])^(ah_reg[2]&d[2])^(ah_reg[1]&d[3]);
  mul2_ahp_t[1]=(ah_reg[1]&d[0])^(mul2_aA&d[1])^(mul2_aB&d[2])^((ah_reg[1]^ah_reg[2])&d[3]);
  mul2_ahp_t[2]=(ah_reg[2]&d[0])^(ah_reg[1]&d[1])^(mul2_aA&d[2])^(mul2_aB&d[3]);
  mul2_ahp_t[3]=(ah_reg[3]&d[0])^(ah_reg[2]&d[1])^(ah_reg[1]&d[2])^(mul2_aA&d[3]);
 
  ahp = (mul2_ahp_t);
 
end
 
 
//mul3:
reg[3:0] mul3_alp_t;
reg[3:0] mul3_aA,mul3_aB;
 
always @(d or alph)
begin
 
  //dxal
 
  mul3_aA=d[0]^d[3];
  mul3_aB=d[2]^d[3];
 
  mul3_alp_t[0]=(d[0]&alph[0])^(d[3]&alph[1])^(d[2]&alph[2])^(d[1]&alph[3]);
  mul3_alp_t[1]=(d[1]&alph[0])^(mul3_aA&alph[1])^(mul3_aB&alph[2])^((d[1]^d[2])&alph[3]);
  mul3_alp_t[2]=(d[2]&alph[0])^(d[1]&alph[1])^(mul3_aA&alph[2])^(mul3_aB&alph[3]);
  mul3_alp_t[3]=(d[3]&alph[0])^(d[2]&alph[1])^(d[1]&alph[2])^(mul3_aA&alph[3]);
 
  alp = (mul3_alp_t);
 
end
 
 
//intermediate:
reg[3:0] intermediate_aA,intermediate_aB;
reg[3:0] intermediate_ah2e,intermediate_ah2epl2,intermediate_to_invert_var;
 
always @(ah2 or al2 or alxh)
begin
 
  //ah square is multiplied with e
  intermediate_aA=ah2[0]^ah2[1];
  intermediate_aB=ah2[2]^ah2[3];
  intermediate_ah2e[0]=ah2[1]^intermediate_aB;
  intermediate_ah2e[1]=intermediate_aA;
  intermediate_ah2e[2]=intermediate_aA^ah2[2];
  intermediate_ah2e[3]=intermediate_aA^intermediate_aB;
 
  //Addition of intermediate_ah2e plus al2
  intermediate_ah2epl2[0]=intermediate_ah2e[0]^al2[0];
  intermediate_ah2epl2[1]=intermediate_ah2e[1]^al2[1];
  intermediate_ah2epl2[2]=intermediate_ah2e[2]^al2[2];
  intermediate_ah2epl2[3]=intermediate_ah2e[3]^al2[3];
 
  //Addition of last result with the result o f(alxah)
  intermediate_to_invert_var[0]=intermediate_ah2epl2[0]^alxh[0];
  intermediate_to_invert_var[1]=intermediate_ah2epl2[1]^alxh[1];
  intermediate_to_invert_var[2]=intermediate_ah2epl2[2]^alxh[2];
  intermediate_to_invert_var[3]=intermediate_ah2epl2[3]^alxh[3];
 
  //Registers
  next_to_invert = (intermediate_to_invert_var);
 
end
 
 
//inversion:
reg[3:0] inversion_to_invert_var;
reg[3:0] inversion_aA,inversion_d_t;
 
always @(to_invert)
begin
 
  inversion_to_invert_var=to_invert;
 
  //Invert theresult in GF(2^4)
  inversion_aA=inversion_to_invert_var[1]^inversion_to_invert_var[2]^inversion_to_invert_var[3]^(inversion_to_invert_var[1]&inversion_to_invert_var[2]&inversion_to_invert_var[3]);
  inversion_d_t[0]=inversion_aA^inversion_to_invert_var[0]^(inversion_to_invert_var[0]&inversion_to_invert_var[2])^(inversion_to_invert_var[1]&inversion_to_invert_var[2])^(inversion_to_invert_var[0]&inversion_to_invert_var[1]&inversion_to_invert_var[2]);
  inversion_d_t[1]=(inversion_to_invert_var[0]&inversion_to_invert_var[1])^(inversion_to_invert_var[0]&inversion_to_invert_var[2])^(inversion_to_invert_var[1]&inversion_to_invert_var[2])^inversion_to_invert_var[3]^(inversion_to_invert_var[1]&inversion_to_invert_var[3])^(inversion_to_invert_var[0]&inversion_to_invert_var[1]&inversion_to_invert_var[3]);
  inversion_d_t[2]=(inversion_to_invert_var[0]&inversion_to_invert_var[1])^inversion_to_invert_var[2]^(inversion_to_invert_var[0]&inversion_to_invert_var[2])^inversion_to_invert_var[3]^(inversion_to_invert_var[0]&inversion_to_invert_var[3])^(inversion_to_invert_var[0]&inversion_to_invert_var[2]&inversion_to_invert_var[3]);
  inversion_d_t[3]=inversion_aA^(inversion_to_invert_var[0]&inversion_to_invert_var[3])^(inversion_to_invert_var[1]&inversion_to_invert_var[3])^(inversion_to_invert_var[2]&inversion_to_invert_var[3]);
 
  d = (inversion_d_t);
 
end
 
 
//sum1:
reg[3:0] sum1_alph_t;
 
always @(ah or al)
begin
 
  sum1_alph_t[0]=al[0]^ah[0];
  sum1_alph_t[1]=al[1]^ah[1];
  sum1_alph_t[2]=al[2]^ah[2];
  sum1_alph_t[3]=al[3]^ah[3];
 
  next_alph = (sum1_alph_t);
 
end
 
 
//square1:
reg[3:0] square1_ah_t;
 
always @(ah)
begin
 
  square1_ah_t[0]=ah[0]^ah[2];
  square1_ah_t[1]=ah[2];
  square1_ah_t[2]=ah[1]^ah[3];
  square1_ah_t[3]=ah[3];
 
  ah2 = (square1_ah_t);
 
end
 
 
//square2:
reg[3:0] square2_al_t;
 
always @(al)
begin
 
  square2_al_t[0]=al[0]^al[2];
  square2_al_t[1]=al[2];
  square2_al_t[2]=al[1]^al[3];
  square2_al_t[3]=al[3];
 
  al2 = (square2_al_t);
 
end
 
endmodule