/**
 * @RDE_HEADER@
 * $Id$
 * $HeadURL$
 * $Author$
 */

#include "pws_des_encryption.h"

namespace ProjectionWorkstation
{

constexpr quint32 LB32_MASK = 0x00000001;
constexpr quint64 LB64_MASK = 0x0000000000000001;
constexpr quint64 L64_MASK  = 0x00000000ffffffff;

// Permuted Choice 1 Table [7*8]
constexpr char PC1[] =
{
  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
};

// Permuted Choice 2 Table [6*8]
constexpr char PC2[] =
{
  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
};

// Iteration Shift Array
constexpr char ITERATION_SHIFT[] =
{
//  1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16
  1,  1,  2,  2,  2,  2,  2,  2,  1,  2,  2,  2,  2,  2,  2,  1
};

// Initial Permutation Table [8*8]
constexpr char IP[] =
{
  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
};

// Inverse Initial Permutation Table [8*8]
constexpr char FP[] =
{
  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
};

// Expansion table [6*8]
constexpr char 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
};

// The S-Box tables [8*16*4]
constexpr char SBOX[8][64] =
{
  {
    // 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
  },
  {
    // 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
  },
  {
    // 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
  },
  {
    // 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
  },
  {
    // 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
  },
  {
    // 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
  },
  {
    // 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
  },
  {
    // 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
  }
};

// Post S-Box permutation [4*8]
constexpr char PBOX[] =
{
  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
};

DES::DES(quint64 key)
{
  keygen(key);
}

quint64 DES::encrypt(quint64 block)
{
  return des(block, false);
}

quint64 DES::decrypt(quint64 block)
{
  return des(block, true);
}

quint64 DES::encrypt(quint64 block, quint64 key)
{
  DES des(key);
  return des.des(block, false);
}

quint64 DES::decrypt(quint64 block, quint64 key)
{
  DES des(key);
  return des.des(block, true);
}

void DES::keygen(quint64 key)
{
  // initial key schedule calculation
  quint64 permuted_choice_1 = 0; // 56 bits
  for (quint8 i = 0; i < 56; i++)
  {
    permuted_choice_1 <<= 1;
    permuted_choice_1 |= (key >> (64 - PC1[i])) & LB64_MASK;
  }

  // 28 bits
  quint32 C = (quint32)((permuted_choice_1 >> 28) & 0x000000000fffffff);
  quint32 D = (quint32)(permuted_choice_1 & 0x000000000fffffff);

  // Calculation of the 16 keys
  for (quint8 i = 0; i < 16; i++)
  {
    // key schedule, shifting Ci and Di
    for (quint8 j = 0; j < ITERATION_SHIFT[i]; j++)
    {
      C = (0x0fffffff & (C << 1)) | (0x00000001 & (C >> 27));
      D = (0x0fffffff & (D << 1)) | (0x00000001 & (D >> 27));
    }

    quint64 permuted_choice_2 = (((quint64) C) << 28) | (quint64) D;

    m_subKey[i] = 0; // 48 bits (2*24)
    for (quint8 j = 0; j < 48; j++)
    {
      m_subKey[i] <<= 1;
      m_subKey[i] |= (permuted_choice_2 >> (56 - PC2[j])) & LB64_MASK;
    }
  }
}

quint64 DES::des(quint64 block, bool mode)
{
  // applying initial permutation
  block = ip(block);

  // dividing T' into two 32-bit parts
  quint32 L = (quint32)(block >> 32) & L64_MASK;
  quint32 R = (quint32)(block & L64_MASK);

  // 16 rounds
  for (quint8 i = 0; i < 16; i++)
  {
    quint32 F = mode ? f(R, m_subKey[15 - i]) : f(R, m_subKey[i]);
    feistel(L, R, F);
  }

  // swapping the two parts
  block = (((quint64) R) << 32) | (quint64) L;
  // applying final permutation
  return fp(block);
}

quint64 DES::ip(quint64 block)  // initial Permutation
{
  // initial permutation
  quint64 result = 0;
  for (quint8 i = 0; i < 64; i++)
  {
    result <<= 1;
    result |= (block >> (64 - IP[i])) & LB64_MASK;
  }
  return result;
}

quint64 DES::fp(quint64 block)  // final Permutation
{
  // inverse initial permutation
  quint64 result = 0;
  for (quint8 i = 0; i < 64; i++)
  {
    result <<= 1;
    result |= (block >> (64 - FP[i])) & LB64_MASK;
  }
  return result;
}

void DES::feistel(quint32 &L, quint32 &R, quint32 F)
{
  quint32 temp = R;
  R = L ^ F;
  L = temp;
}

quint32 DES::f(quint32 R, quint64 k) // f(R,k) function
{
  // applying expansion permutation and returning 48-bit data
  quint64 s_input = 0;
  for (quint8 i = 0; i < 48; i++)
  {
    s_input <<= 1;
    s_input |= (quint64)((R >> (32 - EXPANSION[i])) & LB32_MASK);
  }

  // XORing expanded Ri with Ki, the round key
  s_input = s_input ^ k;

  // applying S-Boxes function and returning 32-bit data
  quint32 s_output = 0;
  for (quint8 i = 0; i < 8; i++)
  {
    // Outer bits
    char row = (char)((s_input & (0x0000840000000000 >> 6 * i)) >> (42 - 6 * i));
    row = (row >> 4) | (row & 0x01);

    // Middle 4 bits of input
    char column = (char)((s_input & (0x0000780000000000 >> 6 * i)) >> (43 - 6 * i));

    s_output <<= 4;
    s_output |= (quint32)(SBOX[i][16 * row + column] & 0x0f);
  }

  // applying the round permutation
  quint32 f_result = 0;
  for (quint8 i = 0; i < 32; i++)
  {
    f_result <<= 1;
    f_result |= (s_output >> (32 - PBOX[i])) & LB32_MASK;
  }

  return f_result;
}

} // ProjectionWorkstation