#include<iostream>

#include<fstream>

#include <iomanip>

using namespace std;

unsigned char exp[], log[], inv[];

unsigned char GFmul(unsigned char a, unsigned char b){

    //GF(2^8) 乘法

    unsigned char result = ;

    if((b&) == )result = a;

    b >>= ;

    for(int i = ; i < ; i ++){

        if(a > ){

            a = (a << ) ^ 0x1b;

        }

        else{

            a <<= ;

        }

        if((b&) == ){

            result ^= a;

        }

        b >>= ;

    }

    return result;

}

void generateMulTab(){

    //选择生成元3作为构造乘法表的基础

    const int N = ;

    exp[] = N;

    log[N] = ;

    unsigned char tmp = N;

    for(int i = ; i < ; i ++){

        tmp = GFmul(tmp, N);

        exp[i] = tmp;

        log[tmp] = i;

    }

}

void generateMulInverse(){

    //利用exp来构造乘法逆元

    inv[] = ;

    inv[] = ;

    //若3^m * 3^n = 1 = 3^255，则 m + n = 255

    for(int i = ; i < ; i ++){

        inv[exp[i]] = exp[-i];

    }

}

unsigned char SBoxValue(unsigned char x){

    //返回SBOX对应的值

    bool xb[];

    unsigned char y = inv[x];

    //AES规定的常数项

    const bool N[][] = {, , , , , , , ,

                          , , , , , , , ,

                          , , , , , , , ,

                          , , , , , , , ,

                          , , , , , , , ,

                          , , , , , , , ,

                          , , , , , , , ,

                          , , , , , , , };

    const bool C[] = {, , , , , , , };

    //将y转化为数组用作矩阵运算

    for(int i = ; i < ; i ++){

        xb[i] = (y&);

        y >>= ;

    }

    //矩阵乘法

    bool tmp[];

    for(int i = ; i < ; i ++)tmp[i] = ;

    for(int i = ; i < ; i ++){

        for(int j = ; j < ; j ++){

            tmp[i] ^= (N[i][j] & xb[j]);

        }

        tmp[i] ^= C[i];

    }

    //将数组结果转化为数值

    unsigned char result = ;

    result |= tmp[];

    for(int i = ; i >= ; i --){

        result <<= ;

        if(tmp[i])result |= ;

    }

    return result;

}

int main(){

    //单元测试，输出SBOX的全部值

    generateMulTab();

    generateMulInverse();

    unsigned char SBox[][];

    for(int i = ; i < ; i ++){

        for(int j = ; j < ; j ++){

            unsigned char tmp = i* + j;

            SBox[i][j] = SBoxValue(tmp);

        }

    }

    ofstream write("Test.txt");

    for(int i = ; i < ; i ++){

        for(int j = ; j < ; j ++){

            write<<setiosflags(ios::left)<<setw()<<hex<<(int)SBox[i][j];

        }

        write<<endl;

    }

    write.close();

    return ;

}