1 /*****************************************************************************
2 * css.c: Functions for DVD authentification and unscrambling
3 *****************************************************************************
4 * Copyright (C) 1999-2001 VideoLAN
5 * $Id: css.c,v 1.15 2001/11/12 20:16:32 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 *****************************************************************************/
46 #include "videolan/dvdcss.h"
47 #include "libdvdcss.h"
49 #include "csstables.h"
57 /*****************************************************************************
59 *****************************************************************************/
60 static int CSSGetASF ( dvdcss_handle dvdcss );
61 static void CSSCryptKey ( int i_key_type, int i_varient,
62 u8 const * p_challenge, u8* p_key );
63 static void CSSDecryptKey( u8* p_crypted, u8* p_key, u8 );
64 static int CSSDiscCrack ( dvdcss_handle dvdcss, u8 * p_disc_key );
65 static int CSSTitleCrack( int i_start, unsigned char * p_crypted,
66 unsigned char * p_decrypted,
67 dvd_key_t * p_sector_key, dvd_key_t * p_key );
69 /*****************************************************************************
70 * CSSTest : check if the disc is encrypted or not
71 *****************************************************************************/
72 int CSSTest( dvdcss_handle dvdcss )
74 int i_ret, i_copyright;
76 i_ret = ioctl_ReadCopyright( dvdcss->i_fd, 0 /* i_layer */, &i_copyright );
80 /* Since it's the first ioctl we try to issue, we add a notice */
81 _dvdcss_error( dvdcss, "css error: ioctl_ReadCopyright failed, "
82 "make sure there is a DVD in the drive, and that "
83 "DVD ioctls were compiled in this libdvdcss version" );
91 /*****************************************************************************
92 * CSSAuth : CSS Structure initialisation and DVD authentication.
93 *****************************************************************************
94 * It simulates the mutual authentication between logical unit and host.
95 * Since we don't need the disc key to find the title key, we just run the
96 * basic unavoidable commands to authenticate device and disc.
97 *****************************************************************************/
98 int CSSAuth( dvdcss_handle dvdcss )
100 /* structures defined in cdrom.h or dvdio.h */
101 unsigned char p_buffer[10];
102 char psz_warning[48];
106 dvdcss->css.i_agid = 0;
108 /* Test authentication success */
109 switch( CSSGetASF( dvdcss ) )
115 _dvdcss_debug( dvdcss, "already authenticated" );
119 _dvdcss_debug( dvdcss, "need to authenticate" );
123 /* Init sequence, request AGID */
124 for( i = 1; i < 4 ; ++i )
126 snprintf( psz_warning, sizeof(psz_warning), "requesting AGID %d", i );
127 _dvdcss_debug( dvdcss, psz_warning );
129 i_ret = ioctl_ReportAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
133 /* No error during ioctl: we know the device is authenticated */
137 _dvdcss_error( dvdcss, "ioctl_ReportAgid failed, invalidating" );
139 dvdcss->css.i_agid = 0;
140 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
143 /* Unable to authenticate without AGID */
146 _dvdcss_error( dvdcss, "ioctl_ReportAgid failed, fatal" );
150 for( i = 0 ; i < 10; ++i )
152 dvdcss->css.disc.p_challenge[i] = i;
155 /* Get challenge from host */
156 for( i = 0 ; i < 10 ; ++i )
158 p_buffer[9-i] = dvdcss->css.disc.p_challenge[i];
161 /* Send challenge to LU */
162 if( ioctl_SendChallenge( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
164 _dvdcss_error( dvdcss, "ioctl_SendChallenge failed" );
168 /* Get key1 from LU */
169 if( ioctl_ReportKey1( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0)
171 _dvdcss_error( dvdcss, "ioctl_ReportKey1 failed" );
175 /* Send key1 to host */
176 for( i = 0 ; i < KEY_SIZE ; i++ )
178 dvdcss->css.disc.p_key1[i] = p_buffer[4-i];
181 for( i = 0 ; i < 32 ; ++i )
183 CSSCryptKey( 0, i, dvdcss->css.disc.p_challenge,
184 dvdcss->css.disc.p_key_check );
186 if( memcmp( dvdcss->css.disc.p_key_check,
187 dvdcss->css.disc.p_key1, KEY_SIZE ) == 0 )
189 snprintf( psz_warning, sizeof(psz_warning),
190 "drive authentic, using variant %d", i );
191 _dvdcss_debug( dvdcss, psz_warning );
192 dvdcss->css.disc.i_varient = i;
199 _dvdcss_error( dvdcss, "drive would not authenticate" );
203 /* Get challenge from LU */
204 if( ioctl_ReportChallenge( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
206 _dvdcss_error( dvdcss, "ioctl_ReportKeyChallenge failed" );
210 /* Send challenge to host */
211 for( i = 0 ; i < 10 ; ++i )
213 dvdcss->css.disc.p_challenge[i] = p_buffer[9-i];
216 CSSCryptKey( 1, dvdcss->css.disc.i_varient,
217 dvdcss->css.disc.p_challenge,
218 dvdcss->css.disc.p_key2 );
220 /* Get key2 from host */
221 for( i = 0 ; i < KEY_SIZE ; ++i )
223 p_buffer[4-i] = dvdcss->css.disc.p_key2[i];
226 /* Send key2 to LU */
227 if( ioctl_SendKey2( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
229 _dvdcss_error( dvdcss, "ioctl_SendKey2 failed" );
233 _dvdcss_debug( dvdcss, "authentication established" );
235 memcpy( dvdcss->css.disc.p_challenge,
236 dvdcss->css.disc.p_key1, KEY_SIZE );
237 memcpy( dvdcss->css.disc.p_challenge+KEY_SIZE,
238 dvdcss->css.disc.p_key2, KEY_SIZE );
240 CSSCryptKey( 2, dvdcss->css.disc.i_varient,
241 dvdcss->css.disc.p_challenge,
242 dvdcss->css.disc.p_key_check );
244 _dvdcss_debug( dvdcss, "received session key" );
246 if( dvdcss->css.i_agid < 0 )
251 /* Test authentication success */
252 switch( CSSGetASF( dvdcss ) )
258 _dvdcss_debug( dvdcss, "already authenticated" );
262 _dvdcss_debug( dvdcss, "need to get disc key" );
269 /*****************************************************************************
270 * CSSGetDiscKey : get disc key and optionnaly decrypts it.
271 *****************************************************************************
272 * This function should only be called if DVD ioctls are present.
273 * Two decryption methods are then offered:
274 * -disc key hash crack,
275 * -decryption with player keys if they are available.
276 *****************************************************************************/
277 int CSSGetDiscKey( dvdcss_handle dvdcss )
279 unsigned char p_buffer[2048 + 4 + 1];
286 if( CSSAuth( dvdcss ) )
291 /* Get encrypted disc key */
292 if( ioctl_ReadDiscKey( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
294 _dvdcss_error( dvdcss, "ioctl_ReadDiscKey failed" );
298 /* Unencrypt disc key using bus key */
299 for( i = 0 ; i < 2048 ; i++ )
301 p_buffer[ i ] ^= dvdcss->css.disc.p_key_check[ 4 - (i % KEY_SIZE) ];
303 memcpy( dvdcss->css.disc.p_disc_key, p_buffer, 2048 );
305 switch( dvdcss->i_method )
307 case DVDCSS_METHOD_KEY:
309 /* Decrypt disc key with player keys from csskeys.h */
310 _dvdcss_debug( dvdcss, "decrypting disc key with player keys" );
314 /* Take encrypted disc key and decrypt it */
316 dvdcss->css.disc.p_disc_key
317 + playerkeys[i].i_offset,
319 CSSDecryptKey( disc_key, playerkeys[i].p_key, 0 );
321 /* Encrypt disc key hash with disc key to
322 * check we have disc key */
323 memcpy( test_key, dvdcss->css.disc.p_disc_key, KEY_SIZE );
324 CSSDecryptKey( test_key, disc_key, 0);
328 } while( ( playerkeys[i].i_offset != -1 ) &&
329 ( memcmp( test_key, disc_key, KEY_SIZE ) ) );
331 /* The decrypted disk key will replace the disk key hash */
332 memcpy( dvdcss->css.disc.p_disc_key, disc_key, KEY_SIZE );
335 dvdcss->i_method = DVDCSS_METHOD_DISC;
337 case DVDCSS_METHOD_DISC:
338 /* Crack Disc key to be able to use it */
339 _dvdcss_debug( dvdcss, "cracking disc key with key hash" );
340 _dvdcss_debug( dvdcss, "building 64MB table ... this will take some time" );
341 CSSDiscCrack( dvdcss, dvdcss->css.disc.p_disc_key );
345 _dvdcss_debug( dvdcss, "disc key won't be decrypted" );
352 /*****************************************************************************
353 * CSSGetTitleKey : get title key.
354 *****************************************************************************/
355 int CSSGetTitleKey( dvdcss_handle dvdcss, int i_pos )
360 if( ( dvdcss->i_method == DVDCSS_METHOD_TITLE )
361 || ( dvdcss->b_ioctls == 0 ) )
364 * Title key cracking method from Ethan Hawke,
365 * with Frank A. Stevenson algorithm.
366 * Does not use any player key table and ioctls.
369 u8 p_packstart[4] = { 0x00, 0x00, 0x01, 0xba };
370 boolean_t b_encrypted;
371 boolean_t b_stop_scanning;
376 _dvdcss_debug( dvdcss, "cracking title key ... this may take some time" );
378 for( i = 0 ; i < KEY_SIZE ; i++ )
389 i_pos = dvdcss_seek( dvdcss, i_pos, DVDCSS_NOFLAGS );
390 if( dvdcss_read( dvdcss, p_buf, 1, DVDCSS_NOFLAGS ) != 1 ) break;
392 /* Stop when we find a non MPEG stream block */
393 if( memcmp( p_buf, p_packstart, 4 ) )
395 /* The title is unencrypted */
398 /* dvdcss some times fail to find/crack the key,
399 hope that it's the same as the one in the next title
400 _dvdcss_debug( dvdcss, "no key found at end of title" );
404 /* PES_scrambling_control on and make sure that the packet type
405 is one that can be scrambled */
406 if( p_buf[0x14] & 0x30 && ! ( p_buf[0x11] == 0xbb
407 || p_buf[0x11] == 0xbe
408 || p_buf[0x11] == 0xbf ) )
414 for( i = 2 ; i < 0x30 ; i++ )
417 j < 0x80 && ( p_buf[0x7F - (j%i)] == p_buf[0x7F-j] );
420 if( j > i_best_plen )
428 if( ( i_best_plen > 20 ) && ( i_best_plen / i_best_p >= 2) )
430 i = CSSTitleCrack( 0, &p_buf[0x80],
431 &p_buf[0x80 - ( i_best_plen / i_best_p) *i_best_p],
432 (dvd_key_t*)&p_buf[0x54],
434 b_stop_scanning = ( i >= 0 );
441 /* If we haven't seen any encrypted ones after 3000 blocks stop */
442 if( !b_encrypted && i_blocks_read >= 1000 ) break;
444 } while( !b_stop_scanning );
446 if( b_stop_scanning )
448 memcpy( dvdcss->css.p_title_key, &p_key, sizeof(dvd_key_t) );
449 _dvdcss_debug( dvdcss, "vts key initialized" );
455 _dvdcss_debug( dvdcss, "file was unscrambled" );
464 * if we are here we have a decrypted disc key and ioctls are available
465 * so we can read the title key and decrypt it.
468 _dvdcss_debug( dvdcss, "decrypting title key with disc key" );
470 /* We need to authenticate again for every key
471 * (to get a new session key ?) */
474 /* Get encrypted title key */
475 if( ioctl_ReadTitleKey( dvdcss->i_fd, &dvdcss->css.i_agid,
478 _dvdcss_error( dvdcss, "ioctl_ReadTitleKey failed" );
481 /* Unencrypt title key using bus key */
482 for( i = 0 ; i < KEY_SIZE ; i++ )
484 p_key[ i ] ^= dvdcss->css.disc.p_key_check[ 4 - (i % KEY_SIZE) ];
487 /* Title key decryption needs one inversion 0xff */
488 CSSDecryptKey( p_key, dvdcss->css.disc.p_disc_key, 0xff );
490 memcpy( dvdcss->css.p_title_key, p_key, sizeof(dvd_key_t) );
493 } // (dvdcss->i_method == DVDCSS_METHOD_TITLE) || (dvdcss->b_ioctls == 0)
496 /*****************************************************************************
497 * CSSDescrambleSector: does the actual descrambling of data
498 *****************************************************************************
499 * sec : sector to descramble
500 * key : title key for this sector
501 *****************************************************************************/
502 int CSSDescrambleSector( dvd_key_t p_key, u8* p_sec )
504 unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6;
505 u8* p_end = p_sec + 0x800;
507 /* PES_scrambling_control */
508 if( p_sec[0x14] & 0x30)
510 i_t1 = ((p_key)[0] ^ p_sec[0x54]) | 0x100;
511 i_t2 = (p_key)[1] ^ p_sec[0x55];
512 i_t3 = (((p_key)[2]) | ((p_key)[3] << 8) |
513 ((p_key)[4] << 16)) ^ ((p_sec[0x56]) |
514 (p_sec[0x57] << 8) | (p_sec[0x58] << 16));
516 i_t3 = i_t3 * 2 + 8 - i_t4;
520 while( p_sec != p_end )
522 i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1];
524 i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4;
525 i_t4 = p_css_tab5[i_t4];
526 i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^
527 i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff;
528 i_t3 = (i_t3 << 8 ) | i_t6;
529 i_t6 = p_css_tab4[i_t6];
531 *p_sec = p_css_tab1[*p_sec] ^( i_t5 & 0xff );
540 /* Following functions are local */
542 /*****************************************************************************
543 * CSSGetASF : Get Authentification success flag
544 *****************************************************************************
547 * 0 if the device needs to be authenticated,
549 *****************************************************************************/
550 static int CSSGetASF( dvdcss_handle dvdcss )
555 for( i_agid = 0 ; i_agid < 4 ; i_agid++ )
557 if( ioctl_ReportASF( dvdcss->i_fd, &i_agid, &i_asf ) == 0 )
561 _dvdcss_debug( dvdcss, "GetASF authenticated" );
565 _dvdcss_debug( dvdcss, "GetASF not authenticated" );
572 /* The ioctl process has failed */
573 _dvdcss_error( dvdcss, "GetASF fatal error" );
577 /*****************************************************************************
578 * CSSCryptKey : shuffles bits and unencrypt keys.
579 *****************************************************************************
580 * Used during authentication and disc key negociation in CSSAuth.
581 * i_key_type : 0->key1, 1->key2, 2->buskey.
582 * i_varient : between 0 and 31.
583 *****************************************************************************/
584 static void CSSCryptKey( int i_key_type, int i_varient,
585 u8 const * p_challenge, u8* p_key )
587 /* Permutation table for challenge */
588 u8 pp_perm_challenge[3][10] =
589 { { 1, 3, 0, 7, 5, 2, 9, 6, 4, 8 },
590 { 6, 1, 9, 3, 8, 5, 7, 4, 0, 2 },
591 { 4, 0, 3, 5, 7, 2, 8, 6, 1, 9 } };
593 /* Permutation table for varient table for key2 and buskey */
594 u8 pp_perm_varient[2][32] =
595 { { 0x0a, 0x08, 0x0e, 0x0c, 0x0b, 0x09, 0x0f, 0x0d,
596 0x1a, 0x18, 0x1e, 0x1c, 0x1b, 0x19, 0x1f, 0x1d,
597 0x02, 0x00, 0x06, 0x04, 0x03, 0x01, 0x07, 0x05,
598 0x12, 0x10, 0x16, 0x14, 0x13, 0x11, 0x17, 0x15 },
599 { 0x12, 0x1a, 0x16, 0x1e, 0x02, 0x0a, 0x06, 0x0e,
600 0x10, 0x18, 0x14, 0x1c, 0x00, 0x08, 0x04, 0x0c,
601 0x13, 0x1b, 0x17, 0x1f, 0x03, 0x0b, 0x07, 0x0f,
602 0x11, 0x19, 0x15, 0x1d, 0x01, 0x09, 0x05, 0x0d } };
605 { 0xB7, 0x74, 0x85, 0xD0, 0xCC, 0xDB, 0xCA, 0x73,
606 0x03, 0xFE, 0x31, 0x03, 0x52, 0xE0, 0xB7, 0x42,
607 0x63, 0x16, 0xF2, 0x2A, 0x79, 0x52, 0xFF, 0x1B,
608 0x7A, 0x11, 0xCA, 0x1A, 0x9B, 0x40, 0xAD, 0x01 };
610 /* The "secret" key */
611 u8 p_secret[5] = { 0x55, 0xD6, 0xC4, 0xC5, 0x28 };
617 u8 i_lfsr0_o; /* 1 bit used */
618 u8 i_lfsr1_o; /* 1 bit used */
631 for (i = 9; i >= 0; --i)
632 p_scratch[i] = p_challenge[pp_perm_challenge[i_key_type][i]];
634 i_css_varient = ( i_key_type == 0 ) ? i_varient :
635 pp_perm_varient[i_key_type-1][i_varient];
638 * This encryption engine implements one of 32 variations
639 * one the same theme depending upon the choice in the
640 * varient parameter (0 - 31).
642 * The algorithm itself manipulates a 40 bit input into
644 * The parameter 'input' is 80 bits. It consists of
645 * the 40 bit input value that is to be encrypted followed
646 * by a 40 bit seed value for the pseudo random number
650 /* Feed the secret into the input values such that
651 * we alter the seed to the LFSR's used above, then
652 * generate the bits to play with.
654 for( i = 5 ; --i >= 0 ; )
656 p_tmp1[i] = p_scratch[5 + i] ^ p_secret[i] ^ p_crypt_tab2[i];
660 * We use two LFSR's (seeded from some of the input data bytes) to
661 * generate two streams of pseudo-random bits. These two bit streams
662 * are then combined by simply adding with carry to generate a final
663 * sequence of pseudo-random bits which is stored in the buffer that
664 * 'output' points to the end of - len is the size of this buffer.
666 * The first LFSR is of degree 25, and has a polynomial of:
667 * x^13 + x^5 + x^4 + x^1 + 1
669 * The second LSFR is of degree 17, and has a (primitive) polynomial of:
672 * I don't know if these polynomials are primitive modulo 2, and thus
673 * represent maximal-period LFSR's.
676 * Note that we take the output of each LFSR from the new shifted in
677 * bit, not the old shifted out bit. Thus for ease of use the LFSR's
678 * are implemented in bit reversed order.
682 /* In order to ensure that the LFSR works we need to ensure that the
683 * initial values are non-zero. Thus when we initialise them from
684 * the seed, we ensure that a bit is set.
686 i_lfsr0 = ( p_tmp1[0] << 17 ) | ( p_tmp1[1] << 9 ) |
687 (( p_tmp1[2] & ~7 ) << 1 ) | 8 | ( p_tmp1[2] & 7 );
688 i_lfsr1 = ( p_tmp1[3] << 9 ) | 0x100 | p_tmp1[4];
690 i_index = sizeof(p_bits);
695 for( i_bit = 0, i_val = 0 ; i_bit < 8 ; ++i_bit )
698 i_lfsr0_o = ( ( i_lfsr0 >> 24 ) ^ ( i_lfsr0 >> 21 ) ^
699 ( i_lfsr0 >> 20 ) ^ ( i_lfsr0 >> 12 ) ) & 1;
700 i_lfsr0 = ( i_lfsr0 << 1 ) | i_lfsr0_o;
702 i_lfsr1_o = ( ( i_lfsr1 >> 16 ) ^ ( i_lfsr1 >> 2 ) ) & 1;
703 i_lfsr1 = ( i_lfsr1 << 1 ) | i_lfsr1_o;
705 i_combined = !i_lfsr1_o + i_carry + !i_lfsr0_o;
707 i_carry = ( i_combined >> 1 ) & 1;
708 i_val |= ( i_combined & 1 ) << i_bit;
711 p_bits[--i_index] = i_val;
712 } while( i_index > 0 );
714 /* This term is used throughout the following to
715 * select one of 32 different variations on the
718 i_cse = p_varients[i_css_varient] ^ p_crypt_tab2[i_css_varient];
720 /* Now the actual blocks doing the encryption. Each
721 * of these works on 40 bits at a time and are quite
725 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_scratch[i] )
727 i_index = p_bits[25 + i] ^ p_scratch[i];
728 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
730 p_tmp1[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
732 p_tmp1[4] ^= p_tmp1[0];
734 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] )
736 i_index = p_bits[20 + i] ^ p_tmp1[i];
737 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
739 p_tmp2[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
741 p_tmp2[4] ^= p_tmp2[0];
743 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp2[i] )
745 i_index = p_bits[15 + i] ^ p_tmp2[i];
746 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
747 i_index = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
749 p_tmp1[i] = p_crypt_tab0[i_index] ^ p_crypt_tab2[i_index];
751 p_tmp1[4] ^= p_tmp1[0];
753 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] )
755 i_index = p_bits[10 + i] ^ p_tmp1[i];
756 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
758 i_index = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
760 p_tmp2[i] = p_crypt_tab0[i_index] ^ p_crypt_tab2[i_index];
762 p_tmp2[4] ^= p_tmp2[0];
764 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp2[i] )
766 i_index = p_bits[5 + i] ^ p_tmp2[i];
767 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
769 p_tmp1[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
771 p_tmp1[4] ^= p_tmp1[0];
773 for(i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] )
775 i_index = p_bits[i] ^ p_tmp1[i];
776 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
778 p_key[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
784 /*****************************************************************************
785 * CSSDecryptKey: decrypt p_crypted with p_key.
786 *****************************************************************************
787 * Decryption is slightly dependant on the type of key:
788 * -for disc key, invert is 0x00,
789 * -for title key, invert if 0xff.
790 *****************************************************************************/
791 static void CSSDecryptKey( u8* p_crypted, u8* p_key, u8 invert )
793 unsigned int i_lfsr1_lo;
794 unsigned int i_lfsr1_hi;
795 unsigned int i_lfsr0;
796 unsigned int i_combined;
802 i_lfsr1_lo = p_key[0] | 0x100;
803 i_lfsr1_hi = p_key[1];
805 i_lfsr0 = ( ( p_key[4] << 17 )
807 | ( p_key[2] << 1 ) )
808 + 8 - ( p_key[2] & 7 );
809 i_lfsr0 = ( p_css_tab4[i_lfsr0 & 0xff] << 24 ) |
810 ( p_css_tab4[( i_lfsr0 >> 8 ) & 0xff] << 16 ) |
811 ( p_css_tab4[( i_lfsr0 >> 16 ) & 0xff] << 8 ) |
812 p_css_tab4[( i_lfsr0 >> 24 ) & 0xff];
815 for( i = 0 ; i < KEY_SIZE ; ++i )
817 o_lfsr1 = p_css_tab2[i_lfsr1_hi] ^ p_css_tab3[i_lfsr1_lo];
818 i_lfsr1_hi = i_lfsr1_lo >> 1;
819 i_lfsr1_lo = ( ( i_lfsr1_lo & 1 ) << 8 ) ^ o_lfsr1;
820 o_lfsr1 = p_css_tab4[o_lfsr1];
822 o_lfsr0 = ((((((( i_lfsr0 >> 8 ) ^ i_lfsr0 ) >> 1 )
823 ^ i_lfsr0 ) >> 3 ) ^ i_lfsr0 ) >> 7 );
824 i_lfsr0 = ( i_lfsr0 >> 8 ) | ( o_lfsr0 << 24 );
826 i_combined += ( o_lfsr0 ^ invert ) + o_lfsr1;
827 k[i] = i_combined & 0xff;
831 p_crypted[4] = k[4] ^ p_css_tab1[p_crypted[4]] ^ p_crypted[3];
832 p_crypted[3] = k[3] ^ p_css_tab1[p_crypted[3]] ^ p_crypted[2];
833 p_crypted[2] = k[2] ^ p_css_tab1[p_crypted[2]] ^ p_crypted[1];
834 p_crypted[1] = k[1] ^ p_css_tab1[p_crypted[1]] ^ p_crypted[0];
835 p_crypted[0] = k[0] ^ p_css_tab1[p_crypted[0]] ^ p_crypted[4];
837 p_crypted[4] = k[4] ^ p_css_tab1[p_crypted[4]] ^ p_crypted[3];
838 p_crypted[3] = k[3] ^ p_css_tab1[p_crypted[3]] ^ p_crypted[2];
839 p_crypted[2] = k[2] ^ p_css_tab1[p_crypted[2]] ^ p_crypted[1];
840 p_crypted[1] = k[1] ^ p_css_tab1[p_crypted[1]] ^ p_crypted[0];
841 p_crypted[0] = k[0] ^ p_css_tab1[p_crypted[0]];
846 /*****************************************************************************
847 * CSSDiscCrack: brute force disc key
848 * CSS hash reversal function designed by Frank Stevenson
849 *****************************************************************************
850 * This function uses a big amount of memory to crack the disc key from the
851 * disc key hash, if player keys are not available.
852 *****************************************************************************/
853 #define K1TABLEWIDTH 10
856 * Simple function to test if a candidate key produces the given hash
858 static int investigate( unsigned char* hash, unsigned char *ckey )
860 unsigned char key[5];
861 unsigned char pkey[5];
863 memcpy( key, hash, 5 );
864 memcpy( pkey, ckey, 5 );
866 CSSDecryptKey( key, pkey, 0 );
868 return memcmp( key, pkey, 5 );
871 static int CSSDiscCrack( dvdcss_handle dvdcss, u8 * p_disc_key )
873 unsigned char B[5] = { 0,0,0,0,0 }; /* Second Stage of mangle cipher */
874 unsigned char C[5] = { 0,0,0,0,0 }; /* Output Stage of mangle cipher
876 unsigned char k[5] = { 0,0,0,0,0 }; /* Mangling cipher key
877 * Also output from CSS( C ) */
878 unsigned char out1[5]; /* five first output bytes of LFSR1 */
879 unsigned char out2[5]; /* five first output bytes of LFSR2 */
880 unsigned int lfsr1a; /* upper 9 bits of LFSR1 */
881 unsigned int lfsr1b; /* lower 8 bits of LFSR1 */
882 unsigned int tmp, tmp2, tmp3, tmp4,tmp5;
884 unsigned int nStepA; /* iterator for LFSR1 start state */
885 unsigned int nStepB; /* iterator for possible B[0] */
886 unsigned int nTry; /* iterator for K[1] possibilities */
887 unsigned int nPossibleK1; /* #of possible K[1] values */
888 unsigned char* K1table; /* Lookup table for possible K[1] */
889 unsigned int* BigTable; /* LFSR2 startstate indexed by
890 * 1,2,5 output byte */
893 * Prepare tables for hash reversal
897 /* initialize lookup tables for k[1] */
898 K1table = malloc( 65536 * K1TABLEWIDTH );
899 memset( K1table, 0 , 65536 * K1TABLEWIDTH );
900 if( K1table == NULL )
905 tmp = p_disc_key[0] ^ p_css_tab1[ p_disc_key[1] ];
906 for( i = 0 ; i < 256 ; i++ ) /* k[1] */
908 tmp2 = p_css_tab1[ tmp ^ i ]; /* p_css_tab1[ B[1] ]*/
910 for( j = 0 ; j < 256 ; j++ ) /* B[0] */
912 tmp3 = j ^ tmp2 ^ i; /* C[1] */
913 tmp4 = K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) ]; /* count of entries here */
916 if( tmp4 == K1TABLEWIDTH )
918 _dvdcss_debug( dvdcss, "Table disaster %d", tmp4 );
921 if( tmp4 < K1TABLEWIDTH )
923 K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) + tmp4 ] = i;
925 K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) ] = tmp4;
929 /* Initing our Really big table */
930 BigTable = malloc( 16777216 * sizeof(int) );
931 memset( BigTable, 0 , 16777216 * sizeof(int) );
932 if( BigTable == NULL )
939 _dvdcss_debug( dvdcss, "initializing the big table" );
941 for( i = 0 ; i < 16777216 ; i++ )
944 if( ( i & 0x07ffff ) == 0 )
946 fprintf( stderr, "#" );
949 tmp = (( i + i ) & 0x1fffff0 ) | 0x8 | ( i & 0x7 );
951 for( j = 0 ; j < 5 ; j++ )
953 tmp2=((((((( tmp >> 3 ) ^ tmp ) >> 1 ) ^ tmp ) >> 8 )
954 ^ tmp ) >> 5 ) & 0xff;
955 tmp = ( tmp << 8) | tmp2;
956 out2[j] = p_css_tab4[ tmp2 ];
959 j = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4];
963 /* fprintf( stderr, "\n" ); */
966 * We are done initing, now reverse hash
968 tmp5 = p_disc_key[0] ^ p_css_tab1[ p_disc_key[1] ];
970 for( nStepA = 0 ; nStepA < 65536 ; nStepA ++ )
972 lfsr1a = 0x100 | ( nStepA >> 8 );
973 lfsr1b = nStepA & 0xff;
975 /* Generate 5 first output bytes from lfsr1 */
976 for( i = 0 ; i < 5 ; i++ )
978 tmp = p_css_tab2[ lfsr1b ] ^ p_css_tab3[ lfsr1a ];
979 lfsr1b = lfsr1a >> 1;
980 lfsr1a = ((lfsr1a&1)<<8) ^ tmp;
981 out1[ i ] = p_css_tab4[ tmp ];
984 /* cumpute and cache some variables */
986 C[1] = nStepA & 0xff;
987 tmp = p_disc_key[3] ^ p_css_tab1[ p_disc_key[4] ];
988 tmp2 = p_css_tab1[ p_disc_key[0] ];
990 /* Search through all possible B[0] */
991 for( nStepB = 0 ; nStepB < 256 ; nStepB++ )
993 /* reverse parts of the mangling cipher */
995 k[0] = p_css_tab1[ B[0] ] ^ C[0];
996 B[4] = B[0] ^ k[0] ^ tmp2;
998 nPossibleK1 = K1table[ K1TABLEWIDTH * (256 * B[0] + C[1]) ];
1000 /* Try out all possible values for k[1] */
1001 for( nTry = 0 ; nTry < nPossibleK1 ; nTry++ )
1003 k[1] = K1table[ K1TABLEWIDTH * (256 * B[0] + C[1]) + nTry + 1 ];
1006 /* reconstruct output from LFSR2 */
1007 tmp3 = ( 0x100 + k[0] - out1[0] );
1008 out2[0] = tmp3 & 0xff;
1009 tmp3 = tmp3 & 0x100 ? 0x100 : 0xff;
1010 tmp3 = ( tmp3 + k[1] - out1[1] );
1011 out2[1] = tmp3 & 0xff;
1012 tmp3 = ( 0x100 + k[4] - out1[4] );
1013 out2[4] = tmp3 & 0xff; /* Can be 1 off */
1015 /* test first possible out2[4] */
1016 tmp4 = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4];
1017 tmp4 = BigTable[ tmp4 ];
1019 C[3] = ( tmp4 >> 8 ) & 0xff;
1020 C[4] = ( tmp4 >> 16 ) & 0xff;
1021 B[3] = p_css_tab1[ B[4] ] ^ k[4] ^ C[4];
1022 k[3] = p_disc_key[2] ^ p_css_tab1[ p_disc_key[3] ] ^ B[3];
1023 B[2] = p_css_tab1[ B[3] ] ^ k[3] ^ C[3];
1024 k[2] = p_disc_key[1] ^ p_css_tab1[ p_disc_key[2] ] ^ B[2];
1026 if( ( B[1] ^ p_css_tab1[ B[2] ] ^ k[ 2 ] ) == C[ 2 ] )
1028 if( ! investigate( &p_disc_key[0] , &C[0] ) )
1034 /* Test second possible out2[4] */
1035 out2[4] = ( out2[4] + 0xff ) & 0xff;
1036 tmp4 = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4];
1037 tmp4 = BigTable[ tmp4 ];
1039 C[3] = ( tmp4 >> 8 ) & 0xff;
1040 C[4] = ( tmp4 >> 16 ) & 0xff;
1041 B[3] = p_css_tab1[ B[4] ] ^ k[4] ^ C[4];
1042 k[3] = p_disc_key[2] ^ p_css_tab1[ p_disc_key[3] ] ^ B[3];
1043 B[2] = p_css_tab1[ B[3] ] ^ k[3] ^ C[3];
1044 k[2] = p_disc_key[1] ^ p_css_tab1[ p_disc_key[2] ] ^ B[2];
1046 if( ( B[1] ^ p_css_tab1[ B[2] ] ^ k[ 2 ] ) == C[ 2 ] )
1048 if( ! investigate( &p_disc_key[0] , &C[0] ) )
1059 memcpy( p_disc_key, &C[0], KEY_SIZE );
1067 /*****************************************************************************
1068 * CSSTitleCrack : title key decryption by cracking
1069 * Function designed by Frank Stevenson
1070 *****************************************************************************
1071 * This function is called by CSSGetTitleKey to find a title key, if we've
1072 * chosen to crack title key instead of decrypting it with the disc key.
1073 *****************************************************************************/
1074 static int CSSTitleCrack( int i_start,
1075 unsigned char * p_crypted,
1076 unsigned char * p_decrypted,
1077 dvd_key_t * p_sector_key,
1080 unsigned char p_buffer[10];
1081 unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6;
1083 unsigned int i_candidate;
1088 for( i = 0 ; i < 10 ; i++ )
1090 p_buffer[i] = p_css_tab1[p_crypted[i]] ^ p_decrypted[i];
1093 for( i_try = i_start ; i_try < 0x10000 ; i_try++ )
1095 i_t1 = i_try >> 8 | 0x100;
1096 i_t2 = i_try & 0xff;
1097 i_t3 = 0; /* not needed */
1100 /* iterate cipher 4 times to reconstruct LFSR2 */
1101 for( i = 0 ; i < 4 ; i++ )
1103 /* advance LFSR1 normaly */
1104 i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1];
1106 i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4;
1107 i_t4 = p_css_tab5[i_t4];
1108 /* deduce i_t6 & i_t5 */
1112 i_t6 = ( i_t6 + 0xff ) & 0x0ff;
1119 i_t5 += i_t6 + i_t4;
1120 i_t6 = p_css_tab4[ i_t6 ];
1121 /* feed / advance i_t3 / i_t5 */
1122 i_t3 = ( i_t3 << 8 ) | i_t6;
1128 /* iterate 6 more times to validate candidate key */
1129 for( ; i < 10 ; i++ )
1131 i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1];
1133 i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4;
1134 i_t4 = p_css_tab5[i_t4];
1135 i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^
1136 i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff;
1137 i_t3 = ( i_t3 << 8 ) | i_t6;
1138 i_t6 = p_css_tab4[i_t6];
1139 i_t5 += i_t6 + i_t4;
1140 if( ( i_t5 & 0xff ) != p_buffer[i] )
1150 /* Do 4 backwards steps of iterating t3 to deduce initial state */
1152 for( i = 0 ; i < 4 ; i++ )
1155 i_t3 = ( i_t3 >> 8 );
1156 /* easy to code, and fast enough bruteforce
1157 * search for byte shifted in */
1158 for( j = 0 ; j < 256 ; j++ )
1160 i_t3 = ( i_t3 & 0x1ffff) | ( j << 17 );
1161 i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^
1162 i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff;
1170 i_t4 = ( i_t3 >> 1 ) - 4;
1171 for( i_t5 = 0 ; i_t5 < 8; i_t5++ )
1173 if( ( ( i_t4 + i_t5 ) * 2 + 8 - ( (i_t4 + i_t5 ) & 7 ) )
1176 (*p_key)[0] = i_try>>8;
1177 (*p_key)[1] = i_try & 0xFF;
1178 (*p_key)[2] = ( ( i_t4 + i_t5 ) >> 0) & 0xFF;
1179 (*p_key)[3] = ( ( i_t4 + i_t5 ) >> 8) & 0xFF;
1180 (*p_key)[4] = ( ( i_t4 + i_t5 ) >> 16) & 0xFF;
1189 (*p_key)[0] ^= (*p_sector_key)[0];
1190 (*p_key)[1] ^= (*p_sector_key)[1];
1191 (*p_key)[2] ^= (*p_sector_key)[2];
1192 (*p_key)[3] ^= (*p_sector_key)[3];
1193 (*p_key)[4] ^= (*p_sector_key)[4];