/*
 * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
 *
 * This program is free software: you can use, redistribute, and/or modify
 * it under the terms of the GNU Affero General Public License, version 3
 * or later ("AGPL"), as published by the Free Software Foundation.
 *
 * 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.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "os.h"
#include "tkey.h"

#define ENCRYPTION_MODE 1
#define DECRYPTION_MODE 0

typedef struct {
  unsigned char k[8];
  unsigned char c[4];
  unsigned char d[4];
} key_set;

void generate_key(unsigned char* key);
void generate_sub_keys(unsigned char* main_key, key_set* key_sets);
void process_message(unsigned char* message_piece, unsigned char* processed_piece, key_set* key_sets, int mode);

#if 0
int64_t taosDesGenKey() {
  unsigned int iseed = (unsigned int)time(NULL);
  srand(iseed);

  unsigned char key[8] = {0};
  generate_key(key);

  return *((int64_t*)key);
}
#endif

char* taosDesImp(unsigned char* key, char* src, unsigned int len, int process_mode) {
  unsigned int  number_of_blocks = len / 8;
  unsigned char data_block[9] = {0};
  unsigned char processed_block[9] = {0};
  key_set       key_sets[17]; memset(key_sets, 0, sizeof(key_sets));
  char*         dest = calloc(len + 1, 1);
  generate_sub_keys(key, key_sets);

  for (unsigned int block_count = 0; block_count < number_of_blocks; block_count++) {
    memset(processed_block, 0, 8);
    memcpy(data_block, src + block_count * 8, 8);
    process_message(data_block, processed_block, key_sets, process_mode);
    memcpy(dest + block_count * 8, processed_block, 8);
  }

  return dest;
}

char* taosDesEncode(int64_t key, char* src, int len) {
  if (len % 8 != 0) return NULL;
  unsigned char* keyStr = (unsigned char*)(&key);
  return taosDesImp(keyStr, src, len, ENCRYPTION_MODE);
}

char* taosDesDecode(int64_t key, char* src, int len) {
  unsigned char* keyStr = (unsigned char*)(&key);
  char*          temp = calloc(len + 8, 1);
  memcpy(temp, src, len);
  len += 8;

  char* decode = taosDesImp(keyStr, temp, len, DECRYPTION_MODE);
  free(temp);

  return decode;
}

int initial_key_permutaion[] = {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, 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};

int initial_message_permutation[] = {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,
                                     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};

int key_shift_sizes[] = {-1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};

int sub_key_permutation[] = {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};

int message_expansion[] = {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};

int S1[] = {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};

int S2[] = {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};

int S3[] = {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};

int S4[] = {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};

int S5[] = {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};

int S6[] = {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};

int S7[] = {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};

int S8[] = {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};

int right_sub_message_permutation[] = {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};

int final_message_permutation[] = {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};

void print_char_as_binary(char input) {
  int i;
  for (i = 0; i < 8; i++) {
    char shift_byte = 0x01 << (7 - i);
    if (shift_byte & input) {
      printf("1");
    } else {
      printf("0");
    }
  }
}

void generate_key(unsigned char* key) {
  int i;
  for (i = 0; i < 8; i++) {
    key[i] = taosRand() % 255;
  }
}

void print_key_set(key_set _key_set) {
  int i;
  printf("K: \n");
  for (i = 0; i < 8; i++) {
    printf("%02X : ", _key_set.k[i]);
    print_char_as_binary(_key_set.k[i]);
    printf("\n");
  }
  printf("\nC: \n");

  for (i = 0; i < 4; i++) {
    printf("%02X : ", _key_set.c[i]);
    print_char_as_binary(_key_set.c[i]);
    printf("\n");
  }
  printf("\nD: \n");

  for (i = 0; i < 4; i++) {
    printf("%02X : ", _key_set.d[i]);
    print_char_as_binary(_key_set.d[i]);
    printf("\n");
  }
  printf("\n");
}

void generate_sub_keys(unsigned char* main_key, key_set* key_sets) {
  int           i, j;
  int           shift_size;
  unsigned char shift_byte, first_shift_bits, second_shift_bits, third_shift_bits, fourth_shift_bits;

  for (i = 0; i < 8; i++) {
    key_sets[0].k[i] = 0;
  }

  for (i = 0; i < 56; i++) {
    shift_size = initial_key_permutaion[i];
    shift_byte = 0x80 >> ((shift_size - 1) % 8);
    shift_byte &= main_key[(shift_size - 1) / 8];
    shift_byte <<= ((shift_size - 1) % 8);

    key_sets[0].k[i / 8] |= (shift_byte >> i % 8);
  }

  for (i = 0; i < 3; i++) {
    key_sets[0].c[i] = key_sets[0].k[i];
  }

  key_sets[0].c[3] = key_sets[0].k[3] & 0xF0;

  for (i = 0; i < 3; i++) {
    key_sets[0].d[i] = (key_sets[0].k[i + 3] & 0x0F) << 4;
    key_sets[0].d[i] |= (key_sets[0].k[i + 4] & 0xF0) >> 4;
  }

  key_sets[0].d[3] = (key_sets[0].k[6] & 0x0F) << 4;

  for (i = 1; i < 17; i++) {
    for (j = 0; j < 4; j++) {
      key_sets[i].c[j] = key_sets[i - 1].c[j];
      key_sets[i].d[j] = key_sets[i - 1].d[j];
    }

    shift_size = key_shift_sizes[i];
    if (shift_size == 1) {
      shift_byte = 0x80;
    } else {
      shift_byte = 0xC0;
    }

    // Process C
    first_shift_bits = shift_byte & key_sets[i].c[0];
    second_shift_bits = shift_byte & key_sets[i].c[1];
    third_shift_bits = shift_byte & key_sets[i].c[2];
    fourth_shift_bits = shift_byte & key_sets[i].c[3];

    key_sets[i].c[0] <<= shift_size;
    key_sets[i].c[0] |= (second_shift_bits >> (8 - shift_size));

    key_sets[i].c[1] <<= shift_size;
    key_sets[i].c[1] |= (third_shift_bits >> (8 - shift_size));

    key_sets[i].c[2] <<= shift_size;
    key_sets[i].c[2] |= (fourth_shift_bits >> (8 - shift_size));

    key_sets[i].c[3] <<= shift_size;
    key_sets[i].c[3] |= (first_shift_bits >> (4 - shift_size));

    // Process D
    first_shift_bits = shift_byte & key_sets[i].d[0];
    second_shift_bits = shift_byte & key_sets[i].d[1];
    third_shift_bits = shift_byte & key_sets[i].d[2];
    fourth_shift_bits = shift_byte & key_sets[i].d[3];

    key_sets[i].d[0] <<= shift_size;
    key_sets[i].d[0] |= (second_shift_bits >> (8 - shift_size));

    key_sets[i].d[1] <<= shift_size;
    key_sets[i].d[1] |= (third_shift_bits >> (8 - shift_size));

    key_sets[i].d[2] <<= shift_size;
    key_sets[i].d[2] |= (fourth_shift_bits >> (8 - shift_size));

    key_sets[i].d[3] <<= shift_size;
    key_sets[i].d[3] |= (first_shift_bits >> (4 - shift_size));

    for (j = 0; j < 48; j++) {
      shift_size = sub_key_permutation[j];
      if (shift_size <= 28) {
        shift_byte = 0x80 >> ((shift_size - 1) % 8);
        shift_byte &= key_sets[i].c[(shift_size - 1) / 8];
        shift_byte <<= ((shift_size - 1) % 8);
      } else {
        shift_byte = 0x80 >> ((shift_size - 29) % 8);
        shift_byte &= key_sets[i].d[(shift_size - 29) / 8];
        shift_byte <<= ((shift_size - 29) % 8);
      }

      key_sets[i].k[j / 8] |= (shift_byte >> j % 8);
    }
  }
}

void process_message(unsigned char* message_piece, unsigned char* processed_piece, key_set* key_sets, int mode) {
  int           i, k;
  int           shift_size;
  unsigned char shift_byte;

  unsigned char initial_permutation[8];
  memset(initial_permutation, 0, 8);
  memset(processed_piece, 0, 8);

  for (i = 0; i < 64; i++) {
    shift_size = initial_message_permutation[i];
    shift_byte = 0x80 >> ((shift_size - 1) % 8);
    shift_byte &= message_piece[(shift_size - 1) / 8];
    shift_byte <<= ((shift_size - 1) % 8);

    initial_permutation[i / 8] |= (shift_byte >> i % 8);
  }

  unsigned char l[4], r[4];
  for (i = 0; i < 4; i++) {
    l[i] = initial_permutation[i];
    r[i] = initial_permutation[i + 4];
  }

  unsigned char ln[4], rn[4], er[6], ser[4];

  int key_index;
  for (k = 1; k <= 16; k++) {
    memcpy(ln, r, 4);

    memset(er, 0, 6);

    for (i = 0; i < 48; i++) {
      shift_size = message_expansion[i];
      shift_byte = 0x80 >> ((shift_size - 1) % 8);
      shift_byte &= r[(shift_size - 1) / 8];
      shift_byte <<= ((shift_size - 1) % 8);

      er[i / 8] |= (shift_byte >> i % 8);
    }

    if (mode == DECRYPTION_MODE) {
      key_index = 17 - k;
    } else {
      key_index = k;
    }

    for (i = 0; i < 6; i++) {
      er[i] ^= key_sets[key_index].k[i];
    }

    unsigned char row, column;

    for (i = 0; i < 4; i++) {
      ser[i] = 0;
    }

    // 0000 0000 0000 0000 0000 0000
    // rccc crrc cccr rccc crrc cccr

    // Byte 1
    row = 0;
    row |= ((er[0] & 0x80) >> 6);
    row |= ((er[0] & 0x04) >> 2);

    column = 0;
    column |= ((er[0] & 0x78) >> 3);

    ser[0] |= ((unsigned char)S1[row * 16 + column] << 4);

    row = 0;
    row |= (er[0] & 0x02);
    row |= ((er[1] & 0x10) >> 4);

    column = 0;
    column |= ((er[0] & 0x01) << 3);
    column |= ((er[1] & 0xE0) >> 5);

    ser[0] |= (unsigned char)S2[row * 16 + column];

    // Byte 2
    row = 0;
    row |= ((er[1] & 0x08) >> 2);
    row |= ((er[2] & 0x40) >> 6);

    column = 0;
    column |= ((er[1] & 0x07) << 1);
    column |= ((er[2] & 0x80) >> 7);

    ser[1] |= ((unsigned char)S3[row * 16 + column] << 4);

    row = 0;
    row |= ((er[2] & 0x20) >> 4);
    row |= (er[2] & 0x01);

    column = 0;
    column |= ((er[2] & 0x1E) >> 1);

    ser[1] |= (unsigned char)S4[row * 16 + column];

    // Byte 3
    row = 0;
    row |= ((er[3] & 0x80) >> 6);
    row |= ((er[3] & 0x04) >> 2);

    column = 0;
    column |= ((er[3] & 0x78) >> 3);

    ser[2] |= ((unsigned char)S5[row * 16 + column] << 4);

    row = 0;
    row |= (er[3] & 0x02);
    row |= ((er[4] & 0x10) >> 4);

    column = 0;
    column |= ((er[3] & 0x01) << 3);
    column |= ((er[4] & 0xE0) >> 5);

    ser[2] |= (unsigned char)S6[row * 16 + column];

    // Byte 4
    row = 0;
    row |= ((er[4] & 0x08) >> 2);
    row |= ((er[5] & 0x40) >> 6);

    column = 0;
    column |= ((er[4] & 0x07) << 1);
    column |= ((er[5] & 0x80) >> 7);

    ser[3] |= ((unsigned char)S7[row * 16 + column] << 4);

    row = 0;
    row |= ((er[5] & 0x20) >> 4);
    row |= (er[5] & 0x01);

    column = 0;
    column |= ((er[5] & 0x1E) >> 1);

    ser[3] |= (unsigned char)S8[row * 16 + column];

    for (i = 0; i < 4; i++) {
      rn[i] = 0;
    }

    for (i = 0; i < 32; i++) {
      shift_size = right_sub_message_permutation[i];
      shift_byte = 0x80 >> ((shift_size - 1) % 8);
      shift_byte &= ser[(shift_size - 1) / 8];
      shift_byte <<= ((shift_size - 1) % 8);

      rn[i / 8] |= (shift_byte >> i % 8);
    }

    for (i = 0; i < 4; i++) {
      rn[i] ^= l[i];
    }

    for (i = 0; i < 4; i++) {
      l[i] = ln[i];
      r[i] = rn[i];
    }
  }

  unsigned char pre_end_permutation[8];
  for (i = 0; i < 4; i++) {
    pre_end_permutation[i] = r[i];
    pre_end_permutation[4 + i] = l[i];
  }

  for (i = 0; i < 64; i++) {
    shift_size = final_message_permutation[i];
    shift_byte = 0x80 >> ((shift_size - 1) % 8);
    shift_byte &= pre_end_permutation[(shift_size - 1) / 8];
    shift_byte <<= ((shift_size - 1) % 8);

    processed_piece[i / 8] |= (shift_byte >> i % 8);
  }
}
