1 /*****************************************************************************
2 * css.c: Functions for DVD authentification and unscrambling
3 *****************************************************************************
4 * Copyright (C) 1999-2001 VideoLAN
5 * $Id: css.c,v 1.18 2001/12/30 07:09:54 sam Exp $
7 * Author: Stéphane Borel <stef@via.ecp.fr>
8 * Håkan Hjort <d95hjort@dtek.chalmers.se>
11 * - css-auth by Derek Fawcus <derek@spider.com>
12 * - DVD CSS ioctls example program by Andrew T. Veliath <andrewtv@usa.net>
13 * - The Divide and conquer attack by Frank A. Stevenson <frank@funcom.com>
14 * - DeCSSPlus by Ethan Hawke
16 * see http://www.lemuria.org/DeCSS/ by Tom Vogt for more information.
18 * This program is free software; you can redistribute it and/or modify
19 * it under the terms of the GNU General Public License as published by
20 * the Free Software Foundation; either version 2 of the License, or
21 * (at your option) any later version.
23 * This program is distributed in the hope that it will be useful,
24 * but WITHOUT ANY WARRANTY; without even the implied warranty of
25 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
26 * GNU General Public License for more details.
28 * You should have received a copy of the GNU General Public License
29 * along with this program; if not, write to the Free Software
30 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
31 *****************************************************************************/
33 /*****************************************************************************
35 *****************************************************************************/
41 #include <videolan/vlc.h>
43 #include "videolan/dvdcss.h"
44 #include "libdvdcss.h"
46 #include "csstables.h"
54 /*****************************************************************************
56 *****************************************************************************/
57 static int CSSGetASF ( dvdcss_handle dvdcss );
58 static void CSSCryptKey ( int i_key_type, int i_varient,
59 u8 const * p_challenge, u8* p_key );
60 static void CSSDecryptKey( u8* p_crypted, u8* p_key, u8 );
61 static int CSSDiscCrack ( dvdcss_handle dvdcss, u8 * p_disc_key );
62 static int CSSTitleCrack( int i_start, unsigned char * p_crypted,
63 unsigned char * p_decrypted,
64 dvd_key_t * p_sector_key, dvd_key_t * p_key );
66 /*****************************************************************************
67 * CSSTest : check if the disc is encrypted or not
68 *****************************************************************************/
69 int CSSTest( dvdcss_handle dvdcss )
71 int i_ret, i_copyright;
73 i_ret = ioctl_ReadCopyright( dvdcss->i_fd, 0 /* i_layer */, &i_copyright );
77 /* Since it's the first ioctl we try to issue, we add a notice */
78 _dvdcss_error( dvdcss, "css error: ioctl_ReadCopyright failed, "
79 "make sure there is a DVD in the drive, and that "
80 "DVD ioctls were compiled in this libdvdcss version" );
88 /*****************************************************************************
89 * CSSAuth : CSS Structure initialisation and DVD authentication.
90 *****************************************************************************
91 * It simulates the mutual authentication between logical unit and host.
92 * Since we don't need the disc key to find the title key, we just run the
93 * basic unavoidable commands to authenticate device and disc.
94 *****************************************************************************/
95 int CSSAuth( dvdcss_handle dvdcss )
97 /* structures defined in cdrom.h or dvdio.h */
98 unsigned char p_buffer[10];
103 dvdcss->css.i_agid = 0;
105 /* Test authentication success */
106 switch( CSSGetASF( dvdcss ) )
112 _dvdcss_debug( dvdcss, "already authenticated" );
116 _dvdcss_debug( dvdcss, "need to authenticate" );
120 /* Init sequence, request AGID */
121 for( i = 1; i < 4 ; ++i )
123 snprintf( psz_warning, sizeof(psz_warning), "requesting AGID %d", i );
124 _dvdcss_debug( dvdcss, psz_warning );
126 i_ret = ioctl_ReportAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
130 /* No error during ioctl: we know the device is authenticated */
134 _dvdcss_error( dvdcss, "ioctl_ReportAgid failed, invalidating" );
136 dvdcss->css.i_agid = 0;
137 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
140 /* Unable to authenticate without AGID */
143 _dvdcss_error( dvdcss, "ioctl_ReportAgid failed, fatal" );
147 for( i = 0 ; i < 10; ++i )
149 dvdcss->css.disc.p_challenge[i] = i;
152 /* Get challenge from host */
153 for( i = 0 ; i < 10 ; ++i )
155 p_buffer[9-i] = dvdcss->css.disc.p_challenge[i];
158 /* Send challenge to LU */
159 if( ioctl_SendChallenge( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
161 _dvdcss_error( dvdcss, "ioctl_SendChallenge failed" );
165 /* Get key1 from LU */
166 if( ioctl_ReportKey1( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0)
168 _dvdcss_error( dvdcss, "ioctl_ReportKey1 failed" );
172 /* Send key1 to host */
173 for( i = 0 ; i < KEY_SIZE ; i++ )
175 dvdcss->css.disc.p_key1[i] = p_buffer[4-i];
178 for( i = 0 ; i < 32 ; ++i )
180 CSSCryptKey( 0, i, dvdcss->css.disc.p_challenge,
181 dvdcss->css.disc.p_key_check );
183 if( memcmp( dvdcss->css.disc.p_key_check,
184 dvdcss->css.disc.p_key1, KEY_SIZE ) == 0 )
186 snprintf( psz_warning, sizeof(psz_warning),
187 "drive authentic, using variant %d", i );
188 _dvdcss_debug( dvdcss, psz_warning );
189 dvdcss->css.disc.i_varient = i;
196 _dvdcss_error( dvdcss, "drive would not authenticate" );
200 /* Get challenge from LU */
201 if( ioctl_ReportChallenge( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
203 _dvdcss_error( dvdcss, "ioctl_ReportKeyChallenge failed" );
207 /* Send challenge to host */
208 for( i = 0 ; i < 10 ; ++i )
210 dvdcss->css.disc.p_challenge[i] = p_buffer[9-i];
213 CSSCryptKey( 1, dvdcss->css.disc.i_varient,
214 dvdcss->css.disc.p_challenge,
215 dvdcss->css.disc.p_key2 );
217 /* Get key2 from host */
218 for( i = 0 ; i < KEY_SIZE ; ++i )
220 p_buffer[4-i] = dvdcss->css.disc.p_key2[i];
223 /* Send key2 to LU */
224 if( ioctl_SendKey2( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
226 _dvdcss_error( dvdcss, "ioctl_SendKey2 failed" );
230 _dvdcss_debug( dvdcss, "authentication established" );
232 memcpy( dvdcss->css.disc.p_challenge,
233 dvdcss->css.disc.p_key1, KEY_SIZE );
234 memcpy( dvdcss->css.disc.p_challenge+KEY_SIZE,
235 dvdcss->css.disc.p_key2, KEY_SIZE );
237 CSSCryptKey( 2, dvdcss->css.disc.i_varient,
238 dvdcss->css.disc.p_challenge,
239 dvdcss->css.disc.p_key_check );
241 _dvdcss_debug( dvdcss, "received session key" );
243 if( dvdcss->css.i_agid < 0 )
248 /* Test authentication success */
249 switch( CSSGetASF( dvdcss ) )
255 _dvdcss_debug( dvdcss, "already authenticated" );
259 _dvdcss_debug( dvdcss, "need to get disc key" );
266 /*****************************************************************************
267 * CSSGetDiscKey : get disc key and optionnaly decrypts it.
268 *****************************************************************************
269 * This function should only be called if DVD ioctls are present.
270 * Two decryption methods are then offered:
271 * -disc key hash crack,
272 * -decryption with player keys if they are available.
273 *****************************************************************************/
274 int CSSGetDiscKey( dvdcss_handle dvdcss )
276 unsigned char p_buffer[2048 + 4 + 1];
283 if( CSSAuth( dvdcss ) )
288 /* Get encrypted disc key */
289 if( ioctl_ReadDiscKey( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
291 _dvdcss_error( dvdcss, "ioctl_ReadDiscKey failed" );
295 /* Unencrypt disc key using bus key */
296 for( i = 0 ; i < 2048 ; i++ )
298 p_buffer[ i ] ^= dvdcss->css.disc.p_key_check[ 4 - (i % KEY_SIZE) ];
300 memcpy( dvdcss->css.disc.p_disc_key, p_buffer, 2048 );
302 switch( dvdcss->i_method )
304 case DVDCSS_METHOD_KEY:
306 /* Decrypt disc key with player keys from csskeys.h */
307 _dvdcss_debug( dvdcss, "decrypting disc key with player keys" );
311 /* Take encrypted disc key and decrypt it */
313 dvdcss->css.disc.p_disc_key
314 + playerkeys[i].i_offset,
316 CSSDecryptKey( disc_key, playerkeys[i].p_key, 0 );
318 /* Encrypt disc key hash with disc key to
319 * check we have disc key */
320 memcpy( test_key, dvdcss->css.disc.p_disc_key, KEY_SIZE );
321 CSSDecryptKey( test_key, disc_key, 0);
325 } while( ( playerkeys[i].i_offset != -1 ) &&
326 ( memcmp( test_key, disc_key, KEY_SIZE ) ) );
328 /* The decrypted disk key will replace the disk key hash */
329 memcpy( dvdcss->css.disc.p_disc_key, disc_key, KEY_SIZE );
332 dvdcss->i_method = DVDCSS_METHOD_DISC;
334 case DVDCSS_METHOD_DISC:
335 /* Crack Disc key to be able to use it */
336 _dvdcss_debug( dvdcss, "cracking disc key with key hash" );
337 _dvdcss_debug( dvdcss, "building 64MB table ... this will take some time" );
338 CSSDiscCrack( dvdcss, dvdcss->css.disc.p_disc_key );
342 _dvdcss_debug( dvdcss, "disc key won't be decrypted" );
349 /*****************************************************************************
350 * CSSGetTitleKey : get title key.
351 *****************************************************************************/
352 int CSSGetTitleKey( dvdcss_handle dvdcss, int i_pos )
357 if( ( dvdcss->i_method == DVDCSS_METHOD_TITLE )
358 || ( dvdcss->b_ioctls == 0 ) )
361 * Title key cracking method from Ethan Hawke,
362 * with Frank A. Stevenson algorithm.
363 * Does not use any player key table and ioctls.
366 u8 p_packstart[4] = { 0x00, 0x00, 0x01, 0xba };
367 boolean_t b_encrypted;
368 boolean_t b_stop_scanning;
373 _dvdcss_debug( dvdcss, "cracking title key ... this may take some time" );
375 for( i = 0 ; i < KEY_SIZE ; i++ )
386 i_pos = _dvdcss_seek( dvdcss, i_pos );
387 if( _dvdcss_read( dvdcss, p_buf, 1 ) != 1 ) break;
389 /* Stop when we find a non MPEG stream block */
390 if( memcmp( p_buf, p_packstart, 4 ) )
392 /* The title is unencrypted */
395 /* dvdcss some times fail to find/crack the key,
396 hope that it's the same as the one in the next title
397 _dvdcss_debug( dvdcss, "no key found at end of title" );
401 /* PES_scrambling_control on and make sure that the packet type
402 is one that can be scrambled */
403 if( p_buf[0x14] & 0x30 && ! ( p_buf[0x11] == 0xbb
404 || p_buf[0x11] == 0xbe
405 || p_buf[0x11] == 0xbf ) )
411 for( i = 2 ; i < 0x30 ; i++ )
414 j < 0x80 && ( p_buf[0x7F - (j%i)] == p_buf[0x7F-j] );
417 if( j > i_best_plen )
425 if( ( i_best_plen > 20 ) && ( i_best_plen / i_best_p >= 2) )
427 i = CSSTitleCrack( 0, &p_buf[0x80],
428 &p_buf[0x80 - ( i_best_plen / i_best_p) *i_best_p],
429 (dvd_key_t*)&p_buf[0x54],
431 b_stop_scanning = ( i >= 0 );
438 /* If we haven't seen any encrypted ones after 3000 blocks stop */
439 if( !b_encrypted && i_blocks_read >= 1000 ) break;
441 } while( !b_stop_scanning );
443 if( b_stop_scanning )
445 memcpy( dvdcss->css.p_title_key, &p_key, sizeof(dvd_key_t) );
446 _dvdcss_debug( dvdcss, "vts key initialized" );
452 _dvdcss_debug( dvdcss, "file was unscrambled" );
461 * if we are here we have a decrypted disc key and ioctls are available
462 * so we can read the title key and decrypt it.
465 _dvdcss_debug( dvdcss, "decrypting title key with disc key" );
467 /* We need to authenticate again for every key
468 * (to get a new session key ?) */
471 /* Get encrypted title key */
472 if( ioctl_ReadTitleKey( dvdcss->i_fd, &dvdcss->css.i_agid,
475 _dvdcss_error( dvdcss, "ioctl_ReadTitleKey failed" );
478 /* Unencrypt title key using bus key */
479 for( i = 0 ; i < KEY_SIZE ; i++ )
481 p_key[ i ] ^= dvdcss->css.disc.p_key_check[ 4 - (i % KEY_SIZE) ];
484 /* Title key decryption needs one inversion 0xff */
485 CSSDecryptKey( p_key, dvdcss->css.disc.p_disc_key, 0xff );
487 memcpy( dvdcss->css.p_title_key, p_key, sizeof(dvd_key_t) );
490 } // (dvdcss->i_method == DVDCSS_METHOD_TITLE) || (dvdcss->b_ioctls == 0)
493 /*****************************************************************************
494 * CSSDescrambleSector: does the actual descrambling of data
495 *****************************************************************************
496 * sec : sector to descramble
497 * key : title key for this sector
498 *****************************************************************************/
499 int CSSDescrambleSector( dvd_key_t p_key, u8* p_sec )
501 unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6;
502 u8* p_end = p_sec + 0x800;
504 /* PES_scrambling_control */
505 if( p_sec[0x14] & 0x30)
507 i_t1 = ((p_key)[0] ^ p_sec[0x54]) | 0x100;
508 i_t2 = (p_key)[1] ^ p_sec[0x55];
509 i_t3 = (((p_key)[2]) | ((p_key)[3] << 8) |
510 ((p_key)[4] << 16)) ^ ((p_sec[0x56]) |
511 (p_sec[0x57] << 8) | (p_sec[0x58] << 16));
513 i_t3 = i_t3 * 2 + 8 - i_t4;
517 while( p_sec != p_end )
519 i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1];
521 i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4;
522 i_t4 = p_css_tab5[i_t4];
523 i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^
524 i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff;
525 i_t3 = (i_t3 << 8 ) | i_t6;
526 i_t6 = p_css_tab4[i_t6];
528 *p_sec = p_css_tab1[*p_sec] ^( i_t5 & 0xff );
537 /* Following functions are local */
539 /*****************************************************************************
540 * CSSGetASF : Get Authentification success flag
541 *****************************************************************************
544 * 0 if the device needs to be authenticated,
546 *****************************************************************************/
547 static int CSSGetASF( dvdcss_handle dvdcss )
552 for( i_agid = 0 ; i_agid < 4 ; i_agid++ )
554 if( ioctl_ReportASF( dvdcss->i_fd, &i_agid, &i_asf ) == 0 )
558 _dvdcss_debug( dvdcss, "GetASF authenticated" );
562 _dvdcss_debug( dvdcss, "GetASF not authenticated" );
569 /* The ioctl process has failed */
570 _dvdcss_error( dvdcss, "GetASF fatal error" );
574 /*****************************************************************************
575 * CSSCryptKey : shuffles bits and unencrypt keys.
576 *****************************************************************************
577 * Used during authentication and disc key negociation in CSSAuth.
578 * i_key_type : 0->key1, 1->key2, 2->buskey.
579 * i_varient : between 0 and 31.
580 *****************************************************************************/
581 static void CSSCryptKey( int i_key_type, int i_varient,
582 u8 const * p_challenge, u8* p_key )
584 /* Permutation table for challenge */
585 u8 pp_perm_challenge[3][10] =
586 { { 1, 3, 0, 7, 5, 2, 9, 6, 4, 8 },
587 { 6, 1, 9, 3, 8, 5, 7, 4, 0, 2 },
588 { 4, 0, 3, 5, 7, 2, 8, 6, 1, 9 } };
590 /* Permutation table for varient table for key2 and buskey */
591 u8 pp_perm_varient[2][32] =
592 { { 0x0a, 0x08, 0x0e, 0x0c, 0x0b, 0x09, 0x0f, 0x0d,
593 0x1a, 0x18, 0x1e, 0x1c, 0x1b, 0x19, 0x1f, 0x1d,
594 0x02, 0x00, 0x06, 0x04, 0x03, 0x01, 0x07, 0x05,
595 0x12, 0x10, 0x16, 0x14, 0x13, 0x11, 0x17, 0x15 },
596 { 0x12, 0x1a, 0x16, 0x1e, 0x02, 0x0a, 0x06, 0x0e,
597 0x10, 0x18, 0x14, 0x1c, 0x00, 0x08, 0x04, 0x0c,
598 0x13, 0x1b, 0x17, 0x1f, 0x03, 0x0b, 0x07, 0x0f,
599 0x11, 0x19, 0x15, 0x1d, 0x01, 0x09, 0x05, 0x0d } };
602 { 0xB7, 0x74, 0x85, 0xD0, 0xCC, 0xDB, 0xCA, 0x73,
603 0x03, 0xFE, 0x31, 0x03, 0x52, 0xE0, 0xB7, 0x42,
604 0x63, 0x16, 0xF2, 0x2A, 0x79, 0x52, 0xFF, 0x1B,
605 0x7A, 0x11, 0xCA, 0x1A, 0x9B, 0x40, 0xAD, 0x01 };
607 /* The "secret" key */
608 u8 p_secret[5] = { 0x55, 0xD6, 0xC4, 0xC5, 0x28 };
614 u8 i_lfsr0_o; /* 1 bit used */
615 u8 i_lfsr1_o; /* 1 bit used */
628 for (i = 9; i >= 0; --i)
629 p_scratch[i] = p_challenge[pp_perm_challenge[i_key_type][i]];
631 i_css_varient = ( i_key_type == 0 ) ? i_varient :
632 pp_perm_varient[i_key_type-1][i_varient];
635 * This encryption engine implements one of 32 variations
636 * one the same theme depending upon the choice in the
637 * varient parameter (0 - 31).
639 * The algorithm itself manipulates a 40 bit input into
641 * The parameter 'input' is 80 bits. It consists of
642 * the 40 bit input value that is to be encrypted followed
643 * by a 40 bit seed value for the pseudo random number
647 /* Feed the secret into the input values such that
648 * we alter the seed to the LFSR's used above, then
649 * generate the bits to play with.
651 for( i = 5 ; --i >= 0 ; )
653 p_tmp1[i] = p_scratch[5 + i] ^ p_secret[i] ^ p_crypt_tab2[i];
657 * We use two LFSR's (seeded from some of the input data bytes) to
658 * generate two streams of pseudo-random bits. These two bit streams
659 * are then combined by simply adding with carry to generate a final
660 * sequence of pseudo-random bits which is stored in the buffer that
661 * 'output' points to the end of - len is the size of this buffer.
663 * The first LFSR is of degree 25, and has a polynomial of:
664 * x^13 + x^5 + x^4 + x^1 + 1
666 * The second LSFR is of degree 17, and has a (primitive) polynomial of:
669 * I don't know if these polynomials are primitive modulo 2, and thus
670 * represent maximal-period LFSR's.
673 * Note that we take the output of each LFSR from the new shifted in
674 * bit, not the old shifted out bit. Thus for ease of use the LFSR's
675 * are implemented in bit reversed order.
679 /* In order to ensure that the LFSR works we need to ensure that the
680 * initial values are non-zero. Thus when we initialise them from
681 * the seed, we ensure that a bit is set.
683 i_lfsr0 = ( p_tmp1[0] << 17 ) | ( p_tmp1[1] << 9 ) |
684 (( p_tmp1[2] & ~7 ) << 1 ) | 8 | ( p_tmp1[2] & 7 );
685 i_lfsr1 = ( p_tmp1[3] << 9 ) | 0x100 | p_tmp1[4];
687 i_index = sizeof(p_bits);
692 for( i_bit = 0, i_val = 0 ; i_bit < 8 ; ++i_bit )
695 i_lfsr0_o = ( ( i_lfsr0 >> 24 ) ^ ( i_lfsr0 >> 21 ) ^
696 ( i_lfsr0 >> 20 ) ^ ( i_lfsr0 >> 12 ) ) & 1;
697 i_lfsr0 = ( i_lfsr0 << 1 ) | i_lfsr0_o;
699 i_lfsr1_o = ( ( i_lfsr1 >> 16 ) ^ ( i_lfsr1 >> 2 ) ) & 1;
700 i_lfsr1 = ( i_lfsr1 << 1 ) | i_lfsr1_o;
702 i_combined = !i_lfsr1_o + i_carry + !i_lfsr0_o;
704 i_carry = ( i_combined >> 1 ) & 1;
705 i_val |= ( i_combined & 1 ) << i_bit;
708 p_bits[--i_index] = i_val;
709 } while( i_index > 0 );
711 /* This term is used throughout the following to
712 * select one of 32 different variations on the
715 i_cse = p_varients[i_css_varient] ^ p_crypt_tab2[i_css_varient];
717 /* Now the actual blocks doing the encryption. Each
718 * of these works on 40 bits at a time and are quite
722 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_scratch[i] )
724 i_index = p_bits[25 + i] ^ p_scratch[i];
725 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
727 p_tmp1[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
729 p_tmp1[4] ^= p_tmp1[0];
731 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] )
733 i_index = p_bits[20 + i] ^ p_tmp1[i];
734 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
736 p_tmp2[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
738 p_tmp2[4] ^= p_tmp2[0];
740 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp2[i] )
742 i_index = p_bits[15 + i] ^ p_tmp2[i];
743 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
744 i_index = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
746 p_tmp1[i] = p_crypt_tab0[i_index] ^ p_crypt_tab2[i_index];
748 p_tmp1[4] ^= p_tmp1[0];
750 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] )
752 i_index = p_bits[10 + i] ^ p_tmp1[i];
753 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
755 i_index = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
757 p_tmp2[i] = p_crypt_tab0[i_index] ^ p_crypt_tab2[i_index];
759 p_tmp2[4] ^= p_tmp2[0];
761 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp2[i] )
763 i_index = p_bits[5 + i] ^ p_tmp2[i];
764 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
766 p_tmp1[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
768 p_tmp1[4] ^= p_tmp1[0];
770 for(i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] )
772 i_index = p_bits[i] ^ p_tmp1[i];
773 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
775 p_key[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
781 /*****************************************************************************
782 * CSSDecryptKey: decrypt p_crypted with p_key.
783 *****************************************************************************
784 * Decryption is slightly dependant on the type of key:
785 * -for disc key, invert is 0x00,
786 * -for title key, invert if 0xff.
787 *****************************************************************************/
788 static void CSSDecryptKey( u8* p_crypted, u8* p_key, u8 invert )
790 unsigned int i_lfsr1_lo;
791 unsigned int i_lfsr1_hi;
792 unsigned int i_lfsr0;
793 unsigned int i_combined;
799 i_lfsr1_lo = p_key[0] | 0x100;
800 i_lfsr1_hi = p_key[1];
802 i_lfsr0 = ( ( p_key[4] << 17 )
804 | ( p_key[2] << 1 ) )
805 + 8 - ( p_key[2] & 7 );
806 i_lfsr0 = ( p_css_tab4[i_lfsr0 & 0xff] << 24 ) |
807 ( p_css_tab4[( i_lfsr0 >> 8 ) & 0xff] << 16 ) |
808 ( p_css_tab4[( i_lfsr0 >> 16 ) & 0xff] << 8 ) |
809 p_css_tab4[( i_lfsr0 >> 24 ) & 0xff];
812 for( i = 0 ; i < KEY_SIZE ; ++i )
814 o_lfsr1 = p_css_tab2[i_lfsr1_hi] ^ p_css_tab3[i_lfsr1_lo];
815 i_lfsr1_hi = i_lfsr1_lo >> 1;
816 i_lfsr1_lo = ( ( i_lfsr1_lo & 1 ) << 8 ) ^ o_lfsr1;
817 o_lfsr1 = p_css_tab4[o_lfsr1];
819 o_lfsr0 = ((((((( i_lfsr0 >> 8 ) ^ i_lfsr0 ) >> 1 )
820 ^ i_lfsr0 ) >> 3 ) ^ i_lfsr0 ) >> 7 );
821 i_lfsr0 = ( i_lfsr0 >> 8 ) | ( o_lfsr0 << 24 );
823 i_combined += ( o_lfsr0 ^ invert ) + o_lfsr1;
824 k[i] = i_combined & 0xff;
828 p_crypted[4] = k[4] ^ p_css_tab1[p_crypted[4]] ^ p_crypted[3];
829 p_crypted[3] = k[3] ^ p_css_tab1[p_crypted[3]] ^ p_crypted[2];
830 p_crypted[2] = k[2] ^ p_css_tab1[p_crypted[2]] ^ p_crypted[1];
831 p_crypted[1] = k[1] ^ p_css_tab1[p_crypted[1]] ^ p_crypted[0];
832 p_crypted[0] = k[0] ^ p_css_tab1[p_crypted[0]] ^ p_crypted[4];
834 p_crypted[4] = k[4] ^ p_css_tab1[p_crypted[4]] ^ p_crypted[3];
835 p_crypted[3] = k[3] ^ p_css_tab1[p_crypted[3]] ^ p_crypted[2];
836 p_crypted[2] = k[2] ^ p_css_tab1[p_crypted[2]] ^ p_crypted[1];
837 p_crypted[1] = k[1] ^ p_css_tab1[p_crypted[1]] ^ p_crypted[0];
838 p_crypted[0] = k[0] ^ p_css_tab1[p_crypted[0]];
843 /*****************************************************************************
844 * CSSDiscCrack: brute force disc key
845 * CSS hash reversal function designed by Frank Stevenson
846 *****************************************************************************
847 * This function uses a big amount of memory to crack the disc key from the
848 * disc key hash, if player keys are not available.
849 *****************************************************************************/
850 #define K1TABLEWIDTH 10
853 * Simple function to test if a candidate key produces the given hash
855 static int investigate( unsigned char* hash, unsigned char *ckey )
857 unsigned char key[5];
858 unsigned char pkey[5];
860 memcpy( key, hash, 5 );
861 memcpy( pkey, ckey, 5 );
863 CSSDecryptKey( key, pkey, 0 );
865 return memcmp( key, pkey, 5 );
868 static int CSSDiscCrack( dvdcss_handle dvdcss, u8 * p_disc_key )
870 unsigned char B[5] = { 0,0,0,0,0 }; /* Second Stage of mangle cipher */
871 unsigned char C[5] = { 0,0,0,0,0 }; /* Output Stage of mangle cipher
873 unsigned char k[5] = { 0,0,0,0,0 }; /* Mangling cipher key
874 * Also output from CSS( C ) */
875 unsigned char out1[5]; /* five first output bytes of LFSR1 */
876 unsigned char out2[5]; /* five first output bytes of LFSR2 */
877 unsigned int lfsr1a; /* upper 9 bits of LFSR1 */
878 unsigned int lfsr1b; /* lower 8 bits of LFSR1 */
879 unsigned int tmp, tmp2, tmp3, tmp4,tmp5;
881 unsigned int nStepA; /* iterator for LFSR1 start state */
882 unsigned int nStepB; /* iterator for possible B[0] */
883 unsigned int nTry; /* iterator for K[1] possibilities */
884 unsigned int nPossibleK1; /* #of possible K[1] values */
885 unsigned char* K1table; /* Lookup table for possible K[1] */
886 unsigned int* BigTable; /* LFSR2 startstate indexed by
887 * 1,2,5 output byte */
890 * Prepare tables for hash reversal
894 /* initialize lookup tables for k[1] */
895 K1table = malloc( 65536 * K1TABLEWIDTH );
896 memset( K1table, 0 , 65536 * K1TABLEWIDTH );
897 if( K1table == NULL )
902 tmp = p_disc_key[0] ^ p_css_tab1[ p_disc_key[1] ];
903 for( i = 0 ; i < 256 ; i++ ) /* k[1] */
905 tmp2 = p_css_tab1[ tmp ^ i ]; /* p_css_tab1[ B[1] ]*/
907 for( j = 0 ; j < 256 ; j++ ) /* B[0] */
909 tmp3 = j ^ tmp2 ^ i; /* C[1] */
910 tmp4 = K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) ]; /* count of entries here */
913 if( tmp4 == K1TABLEWIDTH )
915 _dvdcss_debug( dvdcss, "Table disaster %d", tmp4 );
918 if( tmp4 < K1TABLEWIDTH )
920 K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) + tmp4 ] = i;
922 K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) ] = tmp4;
926 /* Initing our Really big table */
927 BigTable = malloc( 16777216 * sizeof(int) );
928 memset( BigTable, 0 , 16777216 * sizeof(int) );
929 if( BigTable == NULL )
936 _dvdcss_debug( dvdcss, "initializing the big table" );
938 for( i = 0 ; i < 16777216 ; i++ )
941 if( ( i & 0x07ffff ) == 0 )
943 fprintf( stderr, "#" );
946 tmp = (( i + i ) & 0x1fffff0 ) | 0x8 | ( i & 0x7 );
948 for( j = 0 ; j < 5 ; j++ )
950 tmp2=((((((( tmp >> 3 ) ^ tmp ) >> 1 ) ^ tmp ) >> 8 )
951 ^ tmp ) >> 5 ) & 0xff;
952 tmp = ( tmp << 8) | tmp2;
953 out2[j] = p_css_tab4[ tmp2 ];
956 j = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4];
960 /* fprintf( stderr, "\n" ); */
963 * We are done initing, now reverse hash
965 tmp5 = p_disc_key[0] ^ p_css_tab1[ p_disc_key[1] ];
967 for( nStepA = 0 ; nStepA < 65536 ; nStepA ++ )
969 lfsr1a = 0x100 | ( nStepA >> 8 );
970 lfsr1b = nStepA & 0xff;
972 /* Generate 5 first output bytes from lfsr1 */
973 for( i = 0 ; i < 5 ; i++ )
975 tmp = p_css_tab2[ lfsr1b ] ^ p_css_tab3[ lfsr1a ];
976 lfsr1b = lfsr1a >> 1;
977 lfsr1a = ((lfsr1a&1)<<8) ^ tmp;
978 out1[ i ] = p_css_tab4[ tmp ];
981 /* cumpute and cache some variables */
983 C[1] = nStepA & 0xff;
984 tmp = p_disc_key[3] ^ p_css_tab1[ p_disc_key[4] ];
985 tmp2 = p_css_tab1[ p_disc_key[0] ];
987 /* Search through all possible B[0] */
988 for( nStepB = 0 ; nStepB < 256 ; nStepB++ )
990 /* reverse parts of the mangling cipher */
992 k[0] = p_css_tab1[ B[0] ] ^ C[0];
993 B[4] = B[0] ^ k[0] ^ tmp2;
995 nPossibleK1 = K1table[ K1TABLEWIDTH * (256 * B[0] + C[1]) ];
997 /* Try out all possible values for k[1] */
998 for( nTry = 0 ; nTry < nPossibleK1 ; nTry++ )
1000 k[1] = K1table[ K1TABLEWIDTH * (256 * B[0] + C[1]) + nTry + 1 ];
1003 /* reconstruct output from LFSR2 */
1004 tmp3 = ( 0x100 + k[0] - out1[0] );
1005 out2[0] = tmp3 & 0xff;
1006 tmp3 = tmp3 & 0x100 ? 0x100 : 0xff;
1007 tmp3 = ( tmp3 + k[1] - out1[1] );
1008 out2[1] = tmp3 & 0xff;
1009 tmp3 = ( 0x100 + k[4] - out1[4] );
1010 out2[4] = tmp3 & 0xff; /* Can be 1 off */
1012 /* test first possible out2[4] */
1013 tmp4 = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4];
1014 tmp4 = BigTable[ tmp4 ];
1016 C[3] = ( tmp4 >> 8 ) & 0xff;
1017 C[4] = ( tmp4 >> 16 ) & 0xff;
1018 B[3] = p_css_tab1[ B[4] ] ^ k[4] ^ C[4];
1019 k[3] = p_disc_key[2] ^ p_css_tab1[ p_disc_key[3] ] ^ B[3];
1020 B[2] = p_css_tab1[ B[3] ] ^ k[3] ^ C[3];
1021 k[2] = p_disc_key[1] ^ p_css_tab1[ p_disc_key[2] ] ^ B[2];
1023 if( ( B[1] ^ p_css_tab1[ B[2] ] ^ k[ 2 ] ) == C[ 2 ] )
1025 if( ! investigate( &p_disc_key[0] , &C[0] ) )
1031 /* Test second possible out2[4] */
1032 out2[4] = ( out2[4] + 0xff ) & 0xff;
1033 tmp4 = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4];
1034 tmp4 = BigTable[ tmp4 ];
1036 C[3] = ( tmp4 >> 8 ) & 0xff;
1037 C[4] = ( tmp4 >> 16 ) & 0xff;
1038 B[3] = p_css_tab1[ B[4] ] ^ k[4] ^ C[4];
1039 k[3] = p_disc_key[2] ^ p_css_tab1[ p_disc_key[3] ] ^ B[3];
1040 B[2] = p_css_tab1[ B[3] ] ^ k[3] ^ C[3];
1041 k[2] = p_disc_key[1] ^ p_css_tab1[ p_disc_key[2] ] ^ B[2];
1043 if( ( B[1] ^ p_css_tab1[ B[2] ] ^ k[ 2 ] ) == C[ 2 ] )
1045 if( ! investigate( &p_disc_key[0] , &C[0] ) )
1056 memcpy( p_disc_key, &C[0], KEY_SIZE );
1064 /*****************************************************************************
1065 * CSSTitleCrack : title key decryption by cracking
1066 * Function designed by Frank Stevenson
1067 *****************************************************************************
1068 * This function is called by CSSGetTitleKey to find a title key, if we've
1069 * chosen to crack title key instead of decrypting it with the disc key.
1070 *****************************************************************************/
1071 static int CSSTitleCrack( int i_start,
1072 unsigned char * p_crypted,
1073 unsigned char * p_decrypted,
1074 dvd_key_t * p_sector_key,
1077 unsigned char p_buffer[10];
1078 unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6;
1080 unsigned int i_candidate;
1085 for( i = 0 ; i < 10 ; i++ )
1087 p_buffer[i] = p_css_tab1[p_crypted[i]] ^ p_decrypted[i];
1090 for( i_try = i_start ; i_try < 0x10000 ; i_try++ )
1092 i_t1 = i_try >> 8 | 0x100;
1093 i_t2 = i_try & 0xff;
1094 i_t3 = 0; /* not needed */
1097 /* iterate cipher 4 times to reconstruct LFSR2 */
1098 for( i = 0 ; i < 4 ; i++ )
1100 /* advance LFSR1 normaly */
1101 i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1];
1103 i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4;
1104 i_t4 = p_css_tab5[i_t4];
1105 /* deduce i_t6 & i_t5 */
1109 i_t6 = ( i_t6 + 0xff ) & 0x0ff;
1116 i_t5 += i_t6 + i_t4;
1117 i_t6 = p_css_tab4[ i_t6 ];
1118 /* feed / advance i_t3 / i_t5 */
1119 i_t3 = ( i_t3 << 8 ) | i_t6;
1125 /* iterate 6 more times to validate candidate key */
1126 for( ; i < 10 ; i++ )
1128 i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1];
1130 i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4;
1131 i_t4 = p_css_tab5[i_t4];
1132 i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^
1133 i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff;
1134 i_t3 = ( i_t3 << 8 ) | i_t6;
1135 i_t6 = p_css_tab4[i_t6];
1136 i_t5 += i_t6 + i_t4;
1137 if( ( i_t5 & 0xff ) != p_buffer[i] )
1147 /* Do 4 backwards steps of iterating t3 to deduce initial state */
1149 for( i = 0 ; i < 4 ; i++ )
1152 i_t3 = ( i_t3 >> 8 );
1153 /* easy to code, and fast enough bruteforce
1154 * search for byte shifted in */
1155 for( j = 0 ; j < 256 ; j++ )
1157 i_t3 = ( i_t3 & 0x1ffff) | ( j << 17 );
1158 i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^
1159 i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff;
1167 i_t4 = ( i_t3 >> 1 ) - 4;
1168 for( i_t5 = 0 ; i_t5 < 8; i_t5++ )
1170 if( ( ( i_t4 + i_t5 ) * 2 + 8 - ( (i_t4 + i_t5 ) & 7 ) )
1173 (*p_key)[0] = i_try>>8;
1174 (*p_key)[1] = i_try & 0xFF;
1175 (*p_key)[2] = ( ( i_t4 + i_t5 ) >> 0) & 0xFF;
1176 (*p_key)[3] = ( ( i_t4 + i_t5 ) >> 8) & 0xFF;
1177 (*p_key)[4] = ( ( i_t4 + i_t5 ) >> 16) & 0xFF;
1186 (*p_key)[0] ^= (*p_sector_key)[0];
1187 (*p_key)[1] ^= (*p_sector_key)[1];
1188 (*p_key)[2] ^= (*p_sector_key)[2];
1189 (*p_key)[3] ^= (*p_sector_key)[3];
1190 (*p_key)[4] ^= (*p_sector_key)[4];