src/decss/VobDec.cpp

   1 #include "StdAfx.h"
   2 #include "vobdec.h"
   3
   4 static BYTE reverse[0x100], table[0x100] =
   5 {
   6         0x33, 0x73, 0x3B, 0x26, 0x63, 0x23, 0x6B, 0x76, 0x3E, 0x7E, 0x36, 0x2B, 0x6E, 0x2E, 0x66, 0x7B,
   7         0xD3, 0x93, 0xDB, 0x06, 0x43, 0x03, 0x4B, 0x96, 0xDE, 0x9E, 0xD6, 0x0B, 0x4E, 0x0E, 0x46, 0x9B,
   8         0x57, 0x17, 0x5F, 0x82, 0xC7, 0x87, 0xCF, 0x12, 0x5A, 0x1A, 0x52, 0x8F, 0xCA, 0x8A, 0xC2, 0x1F,
   9         0xD9, 0x99, 0xD1, 0x00, 0x49, 0x09, 0x41, 0x90, 0xD8, 0x98, 0xD0, 0x01, 0x48, 0x08, 0x40, 0x91,
  10         0x3D, 0x7D, 0x35, 0x24, 0x6D, 0x2D, 0x65, 0x74, 0x3C, 0x7C, 0x34, 0x25, 0x6C, 0x2C, 0x64, 0x75,
  11         0xDD, 0x9D, 0xD5, 0x04, 0x4D, 0x0D, 0x45, 0x94, 0xDC, 0x9C, 0xD4, 0x05, 0x4C, 0x0C, 0x44, 0x95,
  12         0x59, 0x19, 0x51, 0x80, 0xC9, 0x89, 0xC1, 0x10, 0x58, 0x18, 0x50, 0x81, 0xC8, 0x88, 0xC0, 0x11,
  13         0xD7, 0x97, 0xDF, 0x02, 0x47, 0x07, 0x4F, 0x92, 0xDA, 0x9A, 0xD2, 0x0F, 0x4A, 0x0A, 0x42, 0x9F,
  14         0x53, 0x13, 0x5B, 0x86, 0xC3, 0x83, 0xCB, 0x16, 0x5E, 0x1E, 0x56, 0x8B, 0xCE, 0x8E, 0xC6, 0x1B,
  15         0xB3, 0xF3, 0xBB, 0xA6, 0xE3, 0xA3, 0xEB, 0xF6, 0xBE, 0xFE, 0xB6, 0xAB, 0xEE, 0xAE, 0xE6, 0xFB,
  16         0x37, 0x77, 0x3F, 0x22, 0x67, 0x27, 0x6F, 0x72, 0x3A, 0x7A, 0x32, 0x2F, 0x6A, 0x2A, 0x62, 0x7F,
  17         0xB9, 0xF9, 0xB1, 0xA0, 0xE9, 0xA9, 0xE1, 0xF0, 0xB8, 0xF8, 0xB0, 0xA1, 0xE8, 0xA8, 0xE0, 0xF1,
  18         0x5D, 0x1D, 0x55, 0x84, 0xCD, 0x8D, 0xC5, 0x14, 0x5C, 0x1C, 0x54, 0x85, 0xCC, 0x8C, 0xC4, 0x15,
  19         0xBD, 0xFD, 0xB5, 0xA4, 0xED, 0xAD, 0xE5, 0xF4, 0xBC, 0xFC, 0xB4, 0xA5, 0xEC, 0xAC, 0xE4, 0xF5,
  20         0x39, 0x79, 0x31, 0x20, 0x69, 0x29, 0x61, 0x70, 0x38, 0x78, 0x30, 0x21, 0x68, 0x28, 0x60, 0x71,
  21         0xB7, 0xF7, 0xBF, 0xA2, 0xE7, 0xA7, 0xEF, 0xF2, 0xBA, 0xFA, 0xB2, 0xAF, 0xEA, 0xAA, 0xE2, 0xFF,
  22 };
  23
  24 CVobDec::CVobDec()
  25 {
  26         m_fFoundKey = false;
  27
  28         for(DWORD loop0 = 0; loop0 < 0x100; loop0++)
  29         {
  30                 BYTE value = 0;
  31
  32                 for(DWORD loop1 = 0; loop1 < 8; loop1++)
  33                 {
  34                         value |= ((loop0 >> loop1) & 1) << (7 - loop1);
  35                 }
  36
  37                 reverse[loop0] = value;
  38         }
  39
  40 }
  41
  42 CVobDec::~CVobDec()
  43 {
  44 }
  45
  46 void CVobDec::ClockLfsr0Forward(int &lfsr0)
  47 {
  48         int temp = (lfsr0 << 3) | (lfsr0 >> 14);
  49         lfsr0 = (lfsr0 >> 8) | ((((((temp << 3) ^ temp) << 3) ^ temp ^ lfsr0) & 0xFF) << 9);
  50 }
  51
  52 void CVobDec::ClockLfsr1Forward(int &lfsr1)
  53 {
  54         lfsr1 = (lfsr1 >> 8) | ((((((((lfsr1 >> 8) ^ lfsr1) >> 1) ^ lfsr1) >> 3) ^ lfsr1) & 0xFF) << 17);
  55 }
  56
  57 void CVobDec::ClockBackward(int &lfsr0, int &lfsr1)
  58 {
  59         int temp0, temp1;
  60
  61         lfsr0 = ((lfsr0 << 8) ^ ((((lfsr0 >> 3) ^ lfsr0) >> 6) & 0xFF)) & ((1 << 17) - 1);
  62         temp0 = ((lfsr1 >> 17) ^ (lfsr1 >> 4)) & 0xFF;
  63         temp1 = (lfsr1 << 5) | (temp0 >> 3);
  64         temp1 = ((temp1 >> 1) ^ temp1) & 0xFF;
  65         lfsr1 = ((lfsr1 << 8) | ((((((temp1 >> 2) ^ temp1) >> 1) ^ temp1) >> 3) ^ temp1 ^ temp0)) & ((1 << 25) - 1);
  66 }
  67
  68 void CVobDec::Salt(const BYTE salt[5], int &lfsr0, int &lfsr1)
  69 {
  70         lfsr0 ^= (reverse[salt[0]] << 9) | reverse[salt[1]];
  71         lfsr1 ^= ((reverse[salt[2]] & 0xE0) << 17) | ((reverse[salt[2]] & 0x1F) << 16) | (reverse[salt[3]] << 8) | reverse[salt[4]];
  72 }
  73
  74 int CVobDec::FindLfsr(const BYTE *crypt, int offset, const BYTE *plain)
  75 {
  76         int loop0, loop1, lfsr0, lfsr1, carry, count;
  77
  78         for(loop0 = count = 0; loop0 != (1 << 18); loop0++)
  79         {
  80                 lfsr0 = loop0 >> 1;
  81                 carry = loop0 & 0x01;
  82
  83                 for(loop1 = lfsr1 = 0; loop1 != 4; loop1++)
  84                 {
  85                         ClockLfsr0Forward(lfsr0);
  86                         carry = (table[crypt[offset + loop1]] ^ plain[loop1]) - ((lfsr0 >> 9) ^ 0xFF) - carry;
  87                         lfsr1 = (lfsr1 >> 8) | ((carry & 0xFF) << 17);
  88                         carry = (carry >> 8) & 0x01;
  89                 }
  90                 for( ; loop1 != 7; loop1++)
  91                 {
  92                         ClockLfsr0Forward(lfsr0);
  93                         ClockLfsr1Forward(lfsr1);
  94                         carry += ((lfsr0 >> 9) ^ 0xFF) + (lfsr1 >> 17);
  95                         if((carry & 0xFF) != (table[crypt[offset + loop1]] ^ plain[loop1]))
  96                         {
  97                                 break;
  98                         }
  99                         carry >>= 8;
 100                 }
 101                 if(loop1 == 7)
 102                 {
 103                         for(loop1 = 0; loop1 != 6; loop1++)
 104                         {
 105                                 ClockBackward(lfsr0, lfsr1);
 106                         }
 107                         carry = ((lfsr0 >> 9) ^ 0xFF) + (lfsr1 >> 17) + (loop0 & 0x01);
 108                         if((carry & 0xFF) == (table[crypt[offset]] ^ plain[0]))
 109                         {
 110                                 for(loop1 = 0; loop1 != offset + 1; loop1++)
 111                                 {
 112                                         ClockBackward(lfsr0, lfsr1);
 113                                 }
 114                                 if(lfsr0 & 0x100 && lfsr1 & 0x200000)
 115                                 {
 116                                         m_lfsr0 = lfsr0;
 117                                         m_lfsr1 = lfsr1;
 118                                         count++;
 119                                 }
 120                         }
 121                 }
 122         }
 123
 124         return count;
 125 }
 126
 127 bool CVobDec::FindKey(BYTE* buff)
 128 {
 129         BYTE plain[7] = {0x00, 0x00, 0x01, 0xBE, 0x00, 0x00, 0xFF};
 130         int offset, left, flag = 0, block = 0, count, maxblock = 20000;
 131
 132         m_fFoundKey = false;
 133
 134         if(buff[0x14] & 0x30)
 135         {
 136                 flag |= 0x01;
 137
 138                 if(*(DWORD*)&buff[0x00] == 0xba010000 && (*(DWORD*)&buff[0x0e] & 0xffffff) == 0x010000)
 139                 {
 140                         offset = 0x14 + (buff[0x12] << 8) + buff[0x13];
 141                         if(0x80 <= offset && offset <= 0x7F9)
 142                         {
 143                                 flag |= 0x02;
 144                                 left = 0x800 - offset - 6;
 145                                 plain[4] = (char)(left >> 8);
 146                                 plain[5] = (char)left;
 147                                 if((count = FindLfsr(buff + 0x80, offset - 0x80, plain)) == 1)
 148                                 {
 149                                         Salt(buff + 0x54, m_lfsr0, m_lfsr1);
 150                                         m_fFoundKey = true;
 151                                 }
 152                                 else if(count)
 153                                 {
 154 //                                      printf(_T("\rblock %d reported %d possible keys, skipping\n"), block, count);
 155                                 }
 156                         }
 157                 }
 158         }
 159
 160         return(m_fFoundKey);
 161 }
 162
 163 void CVobDec::Decrypt(BYTE* buff)
 164 {
 165         if(buff[0x14] & 0x30)
 166         {
 167                 buff[0x14] &= ~0x30;
 168
 169                 int lfsr0 = m_lfsr0, lfsr1 = m_lfsr1;
 170
 171                 Salt(buff + 0x54, lfsr0, lfsr1);
 172
 173                 buff += 0x80;
 174
 175                 for(int loop0 = 0, carry = 0; loop0 != 0x800 - 0x80; loop0++, buff++)
 176                 {
 177                         ClockLfsr0Forward(lfsr0);
 178                         ClockLfsr1Forward(lfsr1);
 179                         carry += ((lfsr0 >> 9) ^ 0xFF) + (lfsr1 >> 17);
 180                         *buff = BYTE(table[*buff] ^ carry);
 181                         carry >>= 8;
 182                 }
 183         }
 184 }