//
// Created by qiufeng on 2020/11/25.
//

#include "des.hpp"


void DES::GenSubKey() {
    // 置换选择 1
    std::bitset<28> key_c0(Permute<64, 28>(original_key, key_table_c0));
    std::bitset<28> key_d0(Permute<64, 28>(original_key, key_table_d0));

    for (auto i = 0; i != 16; i++) {
        // 循环左移
        RotateLeftInPlace(key_c0, key_rotate_left_table[i]);
        RotateLeftInPlace(key_d0, key_rotate_left_table[i]);
        // 拼接
        std::bitset<56> concatenated_key = Concatenate<28>(key_c0, key_d0);
        // 置换选择 2
        sub_keys[i] = Permute<56, 48>(concatenated_key, key_table_2);
    }
}


std::bitset<32> DES::F(const std::bitset<48> &original) {
    std::bitset<32> result;

    for (auto i = 0; i != 8; i++) {
        int row = (original[47 - 6 * i] << 1u) + original[42 - 6 * i];
        int column = (original[46 - 6 * i] << 3u) + (original[45 - 6 * i] << 2u) +
                     (original[44 - 6 * i] << 1u) + original[43 - 6 * i];
        int s_out = s_box[i][row][column];

        result[31 - 4 * i] = (static_cast<unsigned int>(s_out) & 0b1000u) >> 3u;
        result[30 - 4 * i] = (static_cast<unsigned int>(s_out) & 0b100u) >> 2u;
        result[29 - 4 * i] = (static_cast<unsigned int>(s_out) & 0b10u) >> 1u;
        result[28 - 4 * i] = static_cast<unsigned int>(s_out) & 0b1u;
    }

    return result;
}


void DES::IterEncrypt(std::bitset<32> &l, std::bitset<32> &r, const int round) {
    // 选择运算 E
    std::bitset<48> tmp = Permute<32, 48>(r, selection_table_e);
    // 轮密钥加
    tmp ^= sub_keys[round];
    // 暂存 l
    std::bitset<32> tmp_l = l;
    l = r;
    r = tmp_l ^ Permute<32, 32>(F(tmp), permutation_table_p);
}


void DES::SetKey(const std::bitset<64> key) {
    original_key = key;
    GenSubKey();
}


std::bitset<64> DES::Encrypt(std::bitset<64> plaintext) {
    // 初始 IP 置换
    std::bitset<32> l = Permute<64, 32>(plaintext, ip_table_l0);
    std::bitset<32> r = Permute<64, 32>(plaintext, ip_table_r0);
    // 迭代加密
    for (auto i = 0; i != 16; i++) {
        IterEncrypt(l, r, i);
    }
    // IP 逆置换
    return Permute<64, 64>(Concatenate<32>(r, l), reverse_ip_table);
}


std::bitset<64> DES::Decrypt(std::bitset<64> ciphertext) {
    // 初始 IP 置换
    std::bitset<32> l = Permute<64, 32>(ciphertext, ip_table_l0);
    std::bitset<32> r = Permute<64, 32>(ciphertext, ip_table_r0);
    // 迭代加密
    for (auto i = 16; i != 0; i--) {
        IterEncrypt(l, r, i - 1);
    }
    // IP 逆置换
    return Permute<64, 64>(Concatenate<32>(r, l), reverse_ip_table);
}


const std::array<int, 28> DES::key_table_c0 {
        57, 49, 41, 33, 25, 17, 9,
        1, 58, 50, 42, 34, 26, 18,
        10, 2, 59, 51, 43, 35, 27,
        19, 11, 3, 60, 52, 44, 36
};


const std::array<int, 28> DES::key_table_d0 {
        63, 55, 47, 39, 31, 23, 15,
        7, 62, 54, 46, 38, 30, 22,
        14, 6, 61, 53, 45, 37, 29,
        21, 13, 5, 28, 20, 12, 4
};


const std::array<int, 16> DES::key_rotate_left_table {
        1, 1, 2, 2, 2, 2, 2, 2,
        1, 2, 2, 2, 2, 2, 2, 1
};


const std::array<int, 48> DES::key_table_2 = {
        14, 17, 11, 24, 1, 5,
        3, 28, 15, 6, 21, 10,
        23, 19, 12, 4, 26, 8,
        16, 7, 27, 20, 13, 2,
        41, 52, 31, 37, 47, 55,
        30, 40, 51, 45, 33, 48,
        44, 49, 39, 56, 34, 53,
        46, 42, 50, 36, 29, 32
};


const std::array<int, 32> DES::ip_table_l0 = {
        58, 50, 42, 34, 26, 18, 10, 2,
        60, 52, 44, 36, 28, 20, 12, 4,
        62, 54, 46, 38, 30, 22, 14, 6,
        64, 56, 48, 40, 32, 24, 16, 8
};


const std::array<int, 32> DES::ip_table_r0 = {
        57, 49, 41, 33, 25, 17, 9, 1,
        59, 51, 43, 35, 27, 19, 11, 3,
        61, 53, 45, 37, 29, 21, 13, 5,
        63, 55, 47, 39, 31, 23, 15, 7
};


const std::array<int, 48> DES::selection_table_e = {
        32, 1, 2, 3, 4, 5,
        4, 5, 6, 7, 8, 9,
        8, 9, 10, 11, 12, 13,
        12, 13, 14, 15, 16, 17,
        16, 17, 18, 19, 20, 21,
        20, 21, 22, 23, 24, 25,
        24, 25, 26, 27, 28, 29,
        28, 29, 30, 31, 32, 1
};


const int DES::s_box[8][4][16] = {
        {
                14, 4,  13, 1,  2,  15, 11, 8,  3,  10, 6,  12, 5,  9,  0,  7,
                0,  15, 7,  4,  14, 2,  13, 1,  10, 6, 12, 11, 9,  5,  3,  8,
                4,  1,  14, 8,  13, 6,  2,  11, 15, 12, 9,  7,  3,  10, 5,  0,
                15, 12, 8,  2,  4,  9,  1,  7,  5,  11, 3,  14, 10, 0, 6,  13
        },
        {
                15, 1,  8,  14, 6,  11, 3,  4,  9,  7,  2,  13, 12, 0,  5,  10,
                3,  13, 4,  7,  15, 2,  8,  14, 12, 0, 1,  10, 6,  9,  11, 5,
                0,  14, 7,  11, 10, 4,  13, 1,  5,  8,  12, 6,  9,  3,  2,  15,
                13, 8,  10, 1,  3,  15, 4,  2,  11, 6,  7,  12, 0,  5, 14, 9
        },
        {
                10, 0,  9,  14, 6,  3,  15, 5,  1,  13, 12, 7,  11, 4,  2,  8,
                13, 7,  0,  9,  3,  4,  6,  10, 2,  8, 5,  14, 12, 11, 15, 1,
                13, 6,  4,  9,  8,  15, 3,  0,  11, 1,  2,  12, 5,  10, 14, 7,
                1,  10, 13, 0,  6,  9,  8,  7,  4,  15, 14, 3,  11, 5, 2,  12
        },
        {
                7,  13, 14, 3,  0,  6,  9,  10, 1,  2,  8,  5,  11, 12, 4,  15,
                13, 8,  11, 5,  6,  15, 0,  3,  4,  7, 2,  12, 1,  10, 14, 9,
                10, 6,  9,  0,  12, 11, 7,  13, 15, 1,  3,  14, 5,  2,  8,  4,
                3,  15, 0,  6,  10, 1,  13, 8,  9,  4,  5,  11, 12, 7, 2,  14,
        },
        {
                2,  12, 4,  1,  7,  10, 11, 6,  8,  5,  3,  15, 13, 0,  14, 9,
                14, 11, 2,  12, 4,  7,  13, 1,  5,  0, 15, 10, 3,  9,  8,  6,
                4,  2,  1,  11, 10, 13, 7,  8,  15, 9,  12, 5,  6,  3,  0,  14,
                11, 8,  12, 7,  1,  14, 2,  13, 6,  15, 0,  9,  10, 4, 5,  3
        },
        {
                12, 1,  10, 15, 9,  2,  6,  8,  0,  13, 3,  4,  14, 7,  5,  11,
                10, 15, 4,  2,  7,  12, 9,  5,  6,  1, 13, 14, 0,  11, 3,  8,
                9,  14, 15, 5,  2,  8,  12, 3,  7,  0,  4,  10, 1,  13, 11, 6,
                4,  3,  2,  12, 9,  5,  15, 10, 11, 14, 1,  7,  6,  0, 8,  13
        },
        {
                4,  11, 2,  14, 15, 0,  8,  13, 3,  12, 9,  7,  5,  10, 6,  1,
                13, 0,  11, 7,  4,  9,  1,  10, 14, 3, 5,  12, 2,  15, 8,  6,
                1,  4,  11, 13, 12, 3,  7,  14, 10, 15, 6,  8,  0,  5,  9,  2,
                6,  11, 13, 8,  1,  4,  10, 7,  9,  5,  0,  15, 14, 2, 3,  12
        },
        {
                13, 2,  8,  4,  6,  15, 11, 1,  10, 9,  3,  14, 5,  0,  12, 7,
                1,  15, 13, 8,  10, 3,  7,  4,  12, 5, 6,  11, 0,  14, 9,  2,
                7,  11, 4,  1,  9,  12, 14, 2,  0,  6,  10, 13, 15, 3,  5,  8,
                2,  1,  14, 7,  4,  10, 8,  13, 15, 12, 9,  0,  3,  5, 6,  11
        }
};


const std::array<int, 32> DES::permutation_table_p = {
        16, 7, 20, 21,
        29, 12, 28, 17,
        1, 15, 23, 26,
        5, 18, 31, 10,
        2, 8, 24, 14,
        32, 27, 3, 9,
        19, 13, 30, 6,
        22, 11, 4, 25
};


const std::array<int, 64> DES::reverse_ip_table = {
        40, 8, 48, 16, 56, 24, 64, 32,
        39, 7, 47, 15, 55, 23, 63, 31,
        38, 6, 46, 14, 54, 22, 62, 30,
        37, 5, 45, 13, 53, 21, 61, 29,
        36, 4, 44, 12, 52, 20, 60, 28,
        35, 3, 43, 11, 51, 19, 59, 27,
        34, 2, 42, 10, 50, 18, 58, 26,
        33, 1, 41, 9, 49, 17, 57, 25
};