dvdcss: Fix DVD playback with region-free drives
[mplayer/glamo.git] / libdvdcss / css.c
blob1a5ecd0da5f612cb5ef7d291dae98ff6daf70ba2
1 /*****************************************************************************
2 * css.c: Functions for DVD authentication and descrambling
3 *****************************************************************************
4 * Copyright (C) 1999-2008 VideoLAN
5 * $Id$
7 * Authors: Stéphane Borel <stef@via.ecp.fr>
8 * Håkan Hjort <d95hjort@dtek.chalmers.se>
10 * based on:
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 * (see http://www-2.cs.cmu.edu/~dst/DeCSS/FrankStevenson/index.html)
15 * - DeCSSPlus by Ethan Hawke
16 * - DecVOB
17 * see http://www.lemuria.org/DeCSS/ by Tom Vogt for more information.
19 * This library is free software; you can redistribute it and/or modify
20 * it under the terms of the GNU General Public License as published by
21 * the Free Software Foundation; either version 2 of the License, or
22 * (at your option) any later version.
24 * This library is distributed in the hope that it will be useful,
25 * but WITHOUT ANY WARRANTY; without even the implied warranty of
26 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
27 * GNU General Public License for more details.
29 * You should have received a copy of the GNU General Public License along
30 * with this library; if not, write to the Free Software Foundation, Inc.,
31 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
32 *****************************************************************************/
34 /*****************************************************************************
35 * Preamble
36 *****************************************************************************/
37 #include "config.h"
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <sys/types.h>
43 #include <sys/stat.h>
44 #ifdef HAVE_SYS_PARAM_H
45 # include <sys/param.h>
46 #endif
47 #ifdef HAVE_UNISTD_H
48 # include <unistd.h>
49 #endif
50 #include <fcntl.h>
52 #ifdef HAVE_LIMITS_H
53 # include <limits.h>
54 #endif
56 #include "dvdcss/dvdcss.h"
58 #include "common.h"
59 #include "css.h"
60 #include "libdvdcss.h"
61 #include "csstables.h"
62 #include "ioctl.h"
63 #include "device.h"
65 /*****************************************************************************
66 * Local prototypes
67 *****************************************************************************/
68 static void PrintKey ( dvdcss_t, char *, uint8_t const * );
70 static int GetBusKey ( dvdcss_t );
71 static int GetASF ( dvdcss_t );
73 static void CryptKey ( int, int, uint8_t const *, uint8_t * );
74 static void DecryptKey ( uint8_t,
75 uint8_t const *, uint8_t const *, uint8_t * );
77 static int DecryptDiscKey ( dvdcss_t, uint8_t const *, dvd_key_t );
78 static int CrackDiscKey ( dvdcss_t, uint8_t * );
80 static void DecryptTitleKey ( dvd_key_t, dvd_key_t );
81 static int RecoverTitleKey ( int, uint8_t const *,
82 uint8_t const *, uint8_t const *, uint8_t * );
83 static int CrackTitleKey ( dvdcss_t, int, int, dvd_key_t );
85 static int AttackPattern ( uint8_t const[], int, uint8_t * );
86 #if 0
87 static int AttackPadding ( uint8_t const[], int, uint8_t * );
88 #endif
90 /*****************************************************************************
91 * _dvdcss_test: check if the disc is encrypted or not
92 *****************************************************************************
93 * Return values:
94 * 1: DVD is scrambled but can be read
95 * 0: DVD is not scrambled and can be read
96 * -1: could not get "copyright" information
97 * -3: drive is RPC-II, region is not set, and DVD is scrambled: the RPC
98 * scheme will prevent us from reading the scrambled data
99 *****************************************************************************/
100 int _dvdcss_test( dvdcss_t dvdcss )
102 char const *psz_type, *psz_rpc;
103 int i_ret, i_copyright, i_type, i_mask, i_rpc;
105 i_ret = ioctl_ReadCopyright( dvdcss->i_fd, 0 /* i_layer */, &i_copyright );
107 #ifdef WIN32
108 if( i_ret < 0 )
110 /* Maybe we didn't have enough privileges to read the copyright
111 * (see ioctl_ReadCopyright comments).
112 * Apparently, on unencrypted DVDs _dvdcss_disckey() always fails, so
113 * we can check this as a workaround. */
114 i_ret = 0;
115 i_copyright = 1;
116 if( _dvdcss_disckey( dvdcss ) < 0 )
118 i_copyright = 0;
121 #endif
123 if( i_ret < 0 )
125 /* Since it's the first ioctl we try to issue, we add a notice */
126 print_error( dvdcss, "css error: could not get \"copyright\""
127 " information, make sure there is a DVD in the drive,"
128 " and that you have used the correct device node." );
130 return -1;
133 print_debug( dvdcss, "disc reports copyright information 0x%x",
134 i_copyright );
136 i_ret = ioctl_ReportRPC( dvdcss->i_fd, &i_type, &i_mask, &i_rpc);
138 if( i_ret < 0 )
140 print_error( dvdcss, "css error: could not get RPC status" );
141 // do not return an error, the drive might be a region-free one
142 // and we definitely should not just fail for that case.
143 return i_copyright ? 1 : 0;
146 switch( i_rpc )
148 case 0: psz_rpc = "RPC-I"; break;
149 case 1: psz_rpc = "RPC-II"; break;
150 default: psz_rpc = "unknown RPC scheme"; break;
153 switch( i_type )
155 case 0: psz_type = "no region code set"; break;
156 case 1: psz_type = "region code set"; break;
157 case 2: psz_type = "one region change remaining"; break;
158 case 3: psz_type = "region code set permanently"; break;
159 default: psz_type = "unknown status"; break;
162 print_debug( dvdcss, "drive region mask 0x%x, %s, %s",
163 i_mask, psz_rpc, psz_type );
165 if( i_copyright && i_rpc == 1 && i_type == 0 )
167 print_error( dvdcss, "css error: drive will prevent access to "
168 "scrambled data" );
169 return -3;
172 return i_copyright ? 1 : 0;
175 /*****************************************************************************
176 * _dvdcss_title: crack or decrypt the current title key if needed
177 *****************************************************************************
178 * This function should only be called by dvdcss->pf_seek and should eventually
179 * not be external if possible.
180 *****************************************************************************/
181 int _dvdcss_title ( dvdcss_t dvdcss, int i_block )
183 dvd_title_t *p_title;
184 dvd_title_t *p_newtitle;
185 dvd_key_t p_title_key;
186 int i_fd, i_ret = -1, b_cache = 0;
188 if( ! dvdcss->b_scrambled )
190 return 0;
193 /* Check if we've already cracked this key */
194 p_title = dvdcss->p_titles;
195 while( p_title != NULL
196 && p_title->p_next != NULL
197 && p_title->p_next->i_startlb <= i_block )
199 p_title = p_title->p_next;
202 if( p_title != NULL
203 && p_title->i_startlb == i_block )
205 /* We've already cracked this key, nothing to do */
206 memcpy( dvdcss->css.p_title_key, p_title->p_key, sizeof(dvd_key_t) );
207 return 0;
210 /* Check whether the key is in our disk cache */
211 if( dvdcss->psz_cachefile[0] )
213 /* XXX: be careful, we use sprintf and not snprintf */
214 sprintf( dvdcss->psz_block, "%.10x", i_block );
215 i_fd = open( dvdcss->psz_cachefile, O_RDONLY );
216 b_cache = 1;
218 if( i_fd >= 0 )
220 char psz_key[KEY_SIZE * 3];
221 unsigned int k0, k1, k2, k3, k4;
223 psz_key[KEY_SIZE * 3 - 1] = '\0';
225 if( read( i_fd, psz_key, KEY_SIZE * 3 - 1 ) == KEY_SIZE * 3 - 1
226 && sscanf( psz_key, "%x:%x:%x:%x:%x",
227 &k0, &k1, &k2, &k3, &k4 ) == 5 )
229 p_title_key[0] = k0;
230 p_title_key[1] = k1;
231 p_title_key[2] = k2;
232 p_title_key[3] = k3;
233 p_title_key[4] = k4;
234 PrintKey( dvdcss, "title key found in cache ", p_title_key );
236 /* Don't try to save it again */
237 b_cache = 0;
238 i_ret = 1;
241 close( i_fd );
245 /* Crack or decrypt CSS title key for current VTS */
246 if( i_ret < 0 )
248 i_ret = _dvdcss_titlekey( dvdcss, i_block, p_title_key );
250 if( i_ret < 0 )
252 print_error( dvdcss, "fatal error in vts css key" );
253 return i_ret;
256 if( i_ret == 0 )
258 print_debug( dvdcss, "unencrypted title" );
259 /* We cache this anyway, so we don't need to check again. */
263 /* Key is valid, we store it on disk. */
264 if( dvdcss->psz_cachefile[0] && b_cache )
266 i_fd = open( dvdcss->psz_cachefile, O_RDWR|O_CREAT, 0644 );
267 if( i_fd >= 0 )
269 char psz_key[KEY_SIZE * 3 + 2];
271 sprintf( psz_key, "%02x:%02x:%02x:%02x:%02x\r\n",
272 p_title_key[0], p_title_key[1], p_title_key[2],
273 p_title_key[3], p_title_key[4] );
275 write( i_fd, psz_key, KEY_SIZE * 3 + 1 );
276 close( i_fd );
280 /* Find our spot in the list */
281 p_newtitle = NULL;
282 p_title = dvdcss->p_titles;
283 while( ( p_title != NULL ) && ( p_title->i_startlb < i_block ) )
285 p_newtitle = p_title;
286 p_title = p_title->p_next;
289 /* Save the found title */
290 p_title = p_newtitle;
292 /* Write in the new title and its key */
293 p_newtitle = malloc( sizeof( dvd_title_t ) );
294 p_newtitle->i_startlb = i_block;
295 memcpy( p_newtitle->p_key, p_title_key, KEY_SIZE );
297 /* Link it at the head of the (possibly empty) list */
298 if( p_title == NULL )
300 p_newtitle->p_next = dvdcss->p_titles;
301 dvdcss->p_titles = p_newtitle;
303 /* Link the new title inside the list */
304 else
306 p_newtitle->p_next = p_title->p_next;
307 p_title->p_next = p_newtitle;
310 memcpy( dvdcss->css.p_title_key, p_title_key, KEY_SIZE );
311 return 0;
314 /*****************************************************************************
315 * _dvdcss_disckey: get disc key.
316 *****************************************************************************
317 * This function should only be called if DVD ioctls are present.
318 * It will set dvdcss->i_method = DVDCSS_METHOD_TITLE if it fails to find
319 * a valid disc key.
320 * Two decryption methods are offered:
321 * -disc key hash crack,
322 * -decryption with player keys if they are available.
323 *****************************************************************************/
324 int _dvdcss_disckey( dvdcss_t dvdcss )
326 unsigned char p_buffer[ DVD_DISCKEY_SIZE ];
327 dvd_key_t p_disc_key;
328 int i;
330 if( GetBusKey( dvdcss ) < 0 )
332 return -1;
335 /* Get encrypted disc key */
336 if( ioctl_ReadDiscKey( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
338 print_error( dvdcss, "ioctl ReadDiscKey failed" );
339 return -1;
342 /* This should have invaidated the AGID and got us ASF=1. */
343 if( GetASF( dvdcss ) != 1 )
345 /* Region mismatch (or region not set) is the most likely source. */
346 print_error( dvdcss,
347 "ASF not 1 after reading disc key (region mismatch?)" );
348 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
349 return -1;
352 /* Shuffle disc key using bus key */
353 for( i = 0 ; i < DVD_DISCKEY_SIZE ; i++ )
355 p_buffer[ i ] ^= dvdcss->css.p_bus_key[ 4 - (i % KEY_SIZE) ];
358 /* Decrypt disc key */
359 switch( dvdcss->i_method )
361 case DVDCSS_METHOD_KEY:
363 /* Decrypt disc key with player key. */
364 PrintKey( dvdcss, "decrypting disc key ", p_buffer );
365 if( ! DecryptDiscKey( dvdcss, p_buffer, p_disc_key ) )
367 PrintKey( dvdcss, "decrypted disc key is ", p_disc_key );
368 break;
370 print_debug( dvdcss, "failed to decrypt the disc key, "
371 "faulty drive/kernel? "
372 "cracking title keys instead" );
374 /* Fallback, but not to DISC as the disc key might be faulty */
375 memset( p_disc_key, 0, KEY_SIZE );
376 dvdcss->i_method = DVDCSS_METHOD_TITLE;
377 break;
379 case DVDCSS_METHOD_DISC:
381 /* Crack Disc key to be able to use it */
382 memcpy( p_disc_key, p_buffer, KEY_SIZE );
383 PrintKey( dvdcss, "cracking disc key ", p_disc_key );
384 if( ! CrackDiscKey( dvdcss, p_disc_key ) )
386 PrintKey( dvdcss, "cracked disc key is ", p_disc_key );
387 break;
389 print_debug( dvdcss, "failed to crack the disc key" );
390 memset( p_disc_key, 0, KEY_SIZE );
391 dvdcss->i_method = DVDCSS_METHOD_TITLE;
392 break;
394 default:
396 print_debug( dvdcss, "disc key needs not be decrypted" );
397 memset( p_disc_key, 0, KEY_SIZE );
398 break;
401 memcpy( dvdcss->css.p_disc_key, p_disc_key, KEY_SIZE );
403 return 0;
407 /*****************************************************************************
408 * _dvdcss_titlekey: get title key.
409 *****************************************************************************/
410 int _dvdcss_titlekey( dvdcss_t dvdcss, int i_pos, dvd_key_t p_title_key )
412 static uint8_t p_garbage[ DVDCSS_BLOCK_SIZE ]; /* we never read it back */
413 uint8_t p_key[ KEY_SIZE ];
414 int i, i_ret = 0;
416 if( dvdcss->b_ioctls && ( dvdcss->i_method == DVDCSS_METHOD_KEY ||
417 dvdcss->i_method == DVDCSS_METHOD_DISC ) )
419 /* We have a decrypted Disc key and the ioctls are available,
420 * read the title key and decrypt it.
423 print_debug( dvdcss, "getting title key at block %i the classic way",
424 i_pos );
426 /* We need to authenticate again every time to get a new session key */
427 if( GetBusKey( dvdcss ) < 0 )
429 i_ret = -1;
432 /* Get encrypted title key */
433 if( ioctl_ReadTitleKey( dvdcss->i_fd, &dvdcss->css.i_agid,
434 i_pos, p_key ) < 0 )
436 print_debug( dvdcss,
437 "ioctl ReadTitleKey failed (region mismatch?)" );
438 i_ret = -1;
441 /* Test ASF, it will be reset to 0 if we got a Region error */
442 switch( GetASF( dvdcss ) )
444 case -1:
445 /* An error getting the ASF status, something must be wrong. */
446 print_debug( dvdcss, "lost ASF requesting title key" );
447 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
448 i_ret = -1;
449 break;
451 case 0:
452 /* This might either be a title that has no key,
453 * or we encountered a region error. */
454 print_debug( dvdcss, "lost ASF requesting title key" );
455 break;
457 case 1:
458 /* Drive status is ok. */
459 /* If the title key request failed, but we did not loose ASF,
460 * we might stil have the AGID. Other code assume that we
461 * will not after this so invalidate it(?). */
462 if( i_ret < 0 )
464 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
466 break;
469 if( !( i_ret < 0 ) )
471 /* Decrypt title key using the bus key */
472 for( i = 0 ; i < KEY_SIZE ; i++ )
474 p_key[ i ] ^= dvdcss->css.p_bus_key[ 4 - (i % KEY_SIZE) ];
477 /* If p_key is all zero then there really wasn't any key present
478 * even though we got to read it without an error. */
479 if( !( p_key[0] | p_key[1] | p_key[2] | p_key[3] | p_key[4] ) )
481 i_ret = 0;
483 else
485 PrintKey( dvdcss, "initial disc key ", dvdcss->css.p_disc_key );
486 DecryptTitleKey( dvdcss->css.p_disc_key, p_key );
487 PrintKey( dvdcss, "decrypted title key ", p_key );
488 i_ret = 1;
491 /* All went well either there wasn't a key or we have it now. */
492 memcpy( p_title_key, p_key, KEY_SIZE );
493 PrintKey( dvdcss, "title key is ", p_title_key );
495 return i_ret;
498 /* The title key request failed */
499 print_debug( dvdcss, "resetting drive and cracking title key" );
501 /* Read an unscrambled sector and reset the drive */
502 dvdcss->pf_seek( dvdcss, 0 );
503 dvdcss->pf_read( dvdcss, p_garbage, 1 );
504 dvdcss->pf_seek( dvdcss, 0 );
505 _dvdcss_disckey( dvdcss );
507 /* Fallback */
510 /* METHOD is TITLE, we can't use the ioctls or requesting the title key
511 * failed above. For these cases we try to crack the key instead. */
513 /* For now, the read limit is 9Gb / 2048 = 4718592 sectors. */
514 i_ret = CrackTitleKey( dvdcss, i_pos, 4718592, p_key );
516 memcpy( p_title_key, p_key, KEY_SIZE );
517 PrintKey( dvdcss, "title key is ", p_title_key );
519 return i_ret;
522 /*****************************************************************************
523 * _dvdcss_unscramble: does the actual descrambling of data
524 *****************************************************************************
525 * sec : sector to unscramble
526 * key : title key for this sector
527 *****************************************************************************/
528 int _dvdcss_unscramble( dvd_key_t p_key, uint8_t *p_sec )
530 unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6;
531 uint8_t *p_end = p_sec + DVDCSS_BLOCK_SIZE;
533 /* PES_scrambling_control */
534 if( !(p_sec[0x14] & 0x30) )
536 return 0;
539 i_t1 = (p_key[0] ^ p_sec[0x54]) | 0x100;
540 i_t2 = p_key[1] ^ p_sec[0x55];
541 i_t3 = (p_key[2] | (p_key[3] << 8) |
542 (p_key[4] << 16)) ^ (p_sec[0x56] |
543 (p_sec[0x57] << 8) | (p_sec[0x58] << 16));
544 i_t4 = i_t3 & 7;
545 i_t3 = i_t3 * 2 + 8 - i_t4;
546 p_sec += 0x80;
547 i_t5 = 0;
549 while( p_sec != p_end )
551 i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1];
552 i_t2 = i_t1>>1;
553 i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4;
554 i_t4 = p_css_tab5[i_t4];
555 i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^
556 i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff;
557 i_t3 = (i_t3 << 8 ) | i_t6;
558 i_t6 = p_css_tab4[i_t6];
559 i_t5 += i_t6 + i_t4;
560 *p_sec = p_css_tab1[*p_sec] ^ ( i_t5 & 0xff );
561 p_sec++;
562 i_t5 >>= 8;
565 return 0;
568 /* Following functions are local */
570 /*****************************************************************************
571 * GetBusKey : Go through the CSS Authentication process
572 *****************************************************************************
573 * It simulates the mutual authentication between logical unit and host,
574 * and stops when a session key (called bus key) has been established.
575 * Always do the full auth sequence. Some drives seem to lie and always
576 * respond with ASF=1. For instance the old DVD roms on Compaq Armada says
577 * that ASF=1 from the start and then later fail with a 'read of scrambled
578 * block without authentication' error.
579 *****************************************************************************/
580 static int GetBusKey( dvdcss_t dvdcss )
582 uint8_t p_buffer[10];
583 uint8_t p_challenge[2*KEY_SIZE];
584 dvd_key_t p_key1;
585 dvd_key_t p_key2;
586 dvd_key_t p_key_check;
587 uint8_t i_variant = 0;
588 int i_ret = -1;
589 int i;
591 print_debug( dvdcss, "requesting AGID" );
592 i_ret = ioctl_ReportAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
594 /* We might have to reset hung authentication processes in the drive
595 * by invalidating the corresponding AGID'. As long as we haven't got
596 * an AGID, invalidate one (in sequence) and try again. */
597 for( i = 0; i_ret == -1 && i < 4 ; ++i )
599 print_debug( dvdcss, "ioctl ReportAgid failed, "
600 "invalidating AGID %d", i );
602 /* This is really _not good_, should be handled by the OS.
603 * Invalidating an AGID could make another process fail somewhere
604 * in its authentication process. */
605 dvdcss->css.i_agid = i;
606 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
608 print_debug( dvdcss, "requesting AGID" );
609 i_ret = ioctl_ReportAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
612 /* Unable to authenticate without AGID */
613 if( i_ret == -1 )
615 print_error( dvdcss, "ioctl ReportAgid failed, fatal" );
616 return -1;
619 /* Setup a challenge, any values should work */
620 for( i = 0 ; i < 10; ++i )
622 p_challenge[i] = i;
625 /* Get challenge from host */
626 for( i = 0 ; i < 10 ; ++i )
628 p_buffer[9-i] = p_challenge[i];
631 /* Send challenge to LU */
632 if( ioctl_SendChallenge( dvdcss->i_fd,
633 &dvdcss->css.i_agid, p_buffer ) < 0 )
635 print_error( dvdcss, "ioctl SendChallenge failed" );
636 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
637 return -1;
640 /* Get key1 from LU */
641 if( ioctl_ReportKey1( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0)
643 print_error( dvdcss, "ioctl ReportKey1 failed" );
644 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
645 return -1;
648 /* Send key1 to host */
649 for( i = 0 ; i < KEY_SIZE ; i++ )
651 p_key1[i] = p_buffer[4-i];
654 for( i = 0 ; i < 32 ; ++i )
656 CryptKey( 0, i, p_challenge, p_key_check );
658 if( memcmp( p_key_check, p_key1, KEY_SIZE ) == 0 )
660 print_debug( dvdcss, "drive authenticated, using variant %d", i );
661 i_variant = i;
662 break;
666 if( i == 32 )
668 print_error( dvdcss, "drive would not authenticate" );
669 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
670 return -1;
673 /* Get challenge from LU */
674 if( ioctl_ReportChallenge( dvdcss->i_fd,
675 &dvdcss->css.i_agid, p_buffer ) < 0 )
677 print_error( dvdcss, "ioctl ReportKeyChallenge failed" );
678 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
679 return -1;
682 /* Send challenge to host */
683 for( i = 0 ; i < 10 ; ++i )
685 p_challenge[i] = p_buffer[9-i];
688 CryptKey( 1, i_variant, p_challenge, p_key2 );
690 /* Get key2 from host */
691 for( i = 0 ; i < KEY_SIZE ; ++i )
693 p_buffer[4-i] = p_key2[i];
696 /* Send key2 to LU */
697 if( ioctl_SendKey2( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
699 print_error( dvdcss, "ioctl SendKey2 failed" );
700 ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
701 return -1;
704 /* The drive has accepted us as authentic. */
705 print_debug( dvdcss, "authentication established" );
707 memcpy( p_challenge, p_key1, KEY_SIZE );
708 memcpy( p_challenge + KEY_SIZE, p_key2, KEY_SIZE );
710 CryptKey( 2, i_variant, p_challenge, dvdcss->css.p_bus_key );
712 return 0;
715 /*****************************************************************************
716 * PrintKey : debug function that dumps a key value
717 *****************************************************************************/
718 static void PrintKey( dvdcss_t dvdcss, char *prefix, uint8_t const *data )
720 print_debug( dvdcss, "%s%02x:%02x:%02x:%02x:%02x", prefix,
721 data[0], data[1], data[2], data[3], data[4] );
724 /*****************************************************************************
725 * GetASF : Get Authentication success flag
726 *****************************************************************************
727 * Returns :
728 * -1 on ioctl error,
729 * 0 if the device needs to be authenticated,
730 * 1 either.
731 *****************************************************************************/
732 static int GetASF( dvdcss_t dvdcss )
734 int i_asf = 0;
736 if( ioctl_ReportASF( dvdcss->i_fd, NULL, &i_asf ) != 0 )
738 /* The ioctl process has failed */
739 print_error( dvdcss, "GetASF fatal error" );
740 return -1;
743 if( i_asf )
745 print_debug( dvdcss, "GetASF authenticated, ASF=1" );
747 else
749 print_debug( dvdcss, "GetASF not authenticated, ASF=0" );
752 return i_asf;
755 /*****************************************************************************
756 * CryptKey : shuffles bits and unencrypt keys.
757 *****************************************************************************
758 * Used during authentication and disc key negociation in GetBusKey.
759 * i_key_type : 0->key1, 1->key2, 2->buskey.
760 * i_variant : between 0 and 31.
761 *****************************************************************************/
762 static void CryptKey( int i_key_type, int i_variant,
763 uint8_t const *p_challenge, uint8_t *p_key )
765 /* Permutation table for challenge */
766 uint8_t pp_perm_challenge[3][10] =
767 { { 1, 3, 0, 7, 5, 2, 9, 6, 4, 8 },
768 { 6, 1, 9, 3, 8, 5, 7, 4, 0, 2 },
769 { 4, 0, 3, 5, 7, 2, 8, 6, 1, 9 } };
771 /* Permutation table for variant table for key2 and buskey */
772 uint8_t pp_perm_variant[2][32] =
773 { { 0x0a, 0x08, 0x0e, 0x0c, 0x0b, 0x09, 0x0f, 0x0d,
774 0x1a, 0x18, 0x1e, 0x1c, 0x1b, 0x19, 0x1f, 0x1d,
775 0x02, 0x00, 0x06, 0x04, 0x03, 0x01, 0x07, 0x05,
776 0x12, 0x10, 0x16, 0x14, 0x13, 0x11, 0x17, 0x15 },
777 { 0x12, 0x1a, 0x16, 0x1e, 0x02, 0x0a, 0x06, 0x0e,
778 0x10, 0x18, 0x14, 0x1c, 0x00, 0x08, 0x04, 0x0c,
779 0x13, 0x1b, 0x17, 0x1f, 0x03, 0x0b, 0x07, 0x0f,
780 0x11, 0x19, 0x15, 0x1d, 0x01, 0x09, 0x05, 0x0d } };
782 uint8_t p_variants[32] =
783 { 0xB7, 0x74, 0x85, 0xD0, 0xCC, 0xDB, 0xCA, 0x73,
784 0x03, 0xFE, 0x31, 0x03, 0x52, 0xE0, 0xB7, 0x42,
785 0x63, 0x16, 0xF2, 0x2A, 0x79, 0x52, 0xFF, 0x1B,
786 0x7A, 0x11, 0xCA, 0x1A, 0x9B, 0x40, 0xAD, 0x01 };
788 /* The "secret" key */
789 uint8_t p_secret[5] = { 0x55, 0xD6, 0xC4, 0xC5, 0x28 };
791 uint8_t p_bits[30], p_scratch[10], p_tmp1[5], p_tmp2[5];
792 uint8_t i_lfsr0_o; /* 1 bit used */
793 uint8_t i_lfsr1_o; /* 1 bit used */
794 uint8_t i_css_variant, i_cse, i_index, i_combined, i_carry;
795 uint8_t i_val = 0;
796 uint32_t i_lfsr0, i_lfsr1;
797 int i_term = 0;
798 int i_bit;
799 int i;
801 for (i = 9; i >= 0; --i)
802 p_scratch[i] = p_challenge[pp_perm_challenge[i_key_type][i]];
804 i_css_variant = ( i_key_type == 0 ) ? i_variant :
805 pp_perm_variant[i_key_type-1][i_variant];
808 * This encryption engine implements one of 32 variations
809 * one the same theme depending upon the choice in the
810 * variant parameter (0 - 31).
812 * The algorithm itself manipulates a 40 bit input into
813 * a 40 bit output.
814 * The parameter 'input' is 80 bits. It consists of
815 * the 40 bit input value that is to be encrypted followed
816 * by a 40 bit seed value for the pseudo random number
817 * generators.
820 /* Feed the secret into the input values such that
821 * we alter the seed to the LFSR's used above, then
822 * generate the bits to play with.
824 for( i = 5 ; --i >= 0 ; )
826 p_tmp1[i] = p_scratch[5 + i] ^ p_secret[i] ^ p_crypt_tab2[i];
830 * We use two LFSR's (seeded from some of the input data bytes) to
831 * generate two streams of pseudo-random bits. These two bit streams
832 * are then combined by simply adding with carry to generate a final
833 * sequence of pseudo-random bits which is stored in the buffer that
834 * 'output' points to the end of - len is the size of this buffer.
836 * The first LFSR is of degree 25, and has a polynomial of:
837 * x^13 + x^5 + x^4 + x^1 + 1
839 * The second LSFR is of degree 17, and has a (primitive) polynomial of:
840 * x^15 + x^1 + 1
842 * I don't know if these polynomials are primitive modulo 2, and thus
843 * represent maximal-period LFSR's.
846 * Note that we take the output of each LFSR from the new shifted in
847 * bit, not the old shifted out bit. Thus for ease of use the LFSR's
848 * are implemented in bit reversed order.
852 /* In order to ensure that the LFSR works we need to ensure that the
853 * initial values are non-zero. Thus when we initialise them from
854 * the seed, we ensure that a bit is set.
856 i_lfsr0 = ( p_tmp1[0] << 17 ) | ( p_tmp1[1] << 9 ) |
857 (( p_tmp1[2] & ~7 ) << 1 ) | 8 | ( p_tmp1[2] & 7 );
858 i_lfsr1 = ( p_tmp1[3] << 9 ) | 0x100 | p_tmp1[4];
860 i_index = sizeof(p_bits);
861 i_carry = 0;
865 for( i_bit = 0, i_val = 0 ; i_bit < 8 ; ++i_bit )
868 i_lfsr0_o = ( ( i_lfsr0 >> 24 ) ^ ( i_lfsr0 >> 21 ) ^
869 ( i_lfsr0 >> 20 ) ^ ( i_lfsr0 >> 12 ) ) & 1;
870 i_lfsr0 = ( i_lfsr0 << 1 ) | i_lfsr0_o;
872 i_lfsr1_o = ( ( i_lfsr1 >> 16 ) ^ ( i_lfsr1 >> 2 ) ) & 1;
873 i_lfsr1 = ( i_lfsr1 << 1 ) | i_lfsr1_o;
875 i_combined = !i_lfsr1_o + i_carry + !i_lfsr0_o;
876 /* taking bit 1 */
877 i_carry = ( i_combined >> 1 ) & 1;
878 i_val |= ( i_combined & 1 ) << i_bit;
881 p_bits[--i_index] = i_val;
882 } while( i_index > 0 );
884 /* This term is used throughout the following to
885 * select one of 32 different variations on the
886 * algorithm.
888 i_cse = p_variants[i_css_variant] ^ p_crypt_tab2[i_css_variant];
890 /* Now the actual blocks doing the encryption. Each
891 * of these works on 40 bits at a time and are quite
892 * similar.
894 i_index = 0;
895 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_scratch[i] )
897 i_index = p_bits[25 + i] ^ p_scratch[i];
898 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
900 p_tmp1[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
902 p_tmp1[4] ^= p_tmp1[0];
904 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] )
906 i_index = p_bits[20 + i] ^ p_tmp1[i];
907 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
909 p_tmp2[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
911 p_tmp2[4] ^= p_tmp2[0];
913 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp2[i] )
915 i_index = p_bits[15 + i] ^ p_tmp2[i];
916 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
917 i_index = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
919 p_tmp1[i] = p_crypt_tab0[i_index] ^ p_crypt_tab2[i_index];
921 p_tmp1[4] ^= p_tmp1[0];
923 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] )
925 i_index = p_bits[10 + i] ^ p_tmp1[i];
926 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
928 i_index = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
930 p_tmp2[i] = p_crypt_tab0[i_index] ^ p_crypt_tab2[i_index];
932 p_tmp2[4] ^= p_tmp2[0];
934 for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp2[i] )
936 i_index = p_bits[5 + i] ^ p_tmp2[i];
937 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
939 p_tmp1[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
941 p_tmp1[4] ^= p_tmp1[0];
943 for(i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] )
945 i_index = p_bits[i] ^ p_tmp1[i];
946 i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse;
948 p_key[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term;
951 return;
954 /*****************************************************************************
955 * DecryptKey: decrypt p_crypted with p_key.
956 *****************************************************************************
957 * Used to decrypt the disc key, with a player key, after requesting it
958 * in _dvdcss_disckey and to decrypt title keys, with a disc key, requested
959 * in _dvdcss_titlekey.
960 * The player keys and the resulting disc key are only used as KEKs
961 * (key encryption keys).
962 * Decryption is slightly dependant on the type of key:
963 * -for disc key, invert is 0x00,
964 * -for title key, invert if 0xff.
965 *****************************************************************************/
966 static void DecryptKey( uint8_t invert, uint8_t const *p_key,
967 uint8_t const *p_crypted, uint8_t *p_result )
969 unsigned int i_lfsr1_lo;
970 unsigned int i_lfsr1_hi;
971 unsigned int i_lfsr0;
972 unsigned int i_combined;
973 uint8_t o_lfsr0;
974 uint8_t o_lfsr1;
975 uint8_t k[5];
976 int i;
978 i_lfsr1_lo = p_key[0] | 0x100;
979 i_lfsr1_hi = p_key[1];
981 i_lfsr0 = ( ( p_key[4] << 17 )
982 | ( p_key[3] << 9 )
983 | ( p_key[2] << 1 ) )
984 + 8 - ( p_key[2] & 7 );
985 i_lfsr0 = ( p_css_tab4[i_lfsr0 & 0xff] << 24 ) |
986 ( p_css_tab4[( i_lfsr0 >> 8 ) & 0xff] << 16 ) |
987 ( p_css_tab4[( i_lfsr0 >> 16 ) & 0xff] << 8 ) |
988 p_css_tab4[( i_lfsr0 >> 24 ) & 0xff];
990 i_combined = 0;
991 for( i = 0 ; i < KEY_SIZE ; ++i )
993 o_lfsr1 = p_css_tab2[i_lfsr1_hi] ^ p_css_tab3[i_lfsr1_lo];
994 i_lfsr1_hi = i_lfsr1_lo >> 1;
995 i_lfsr1_lo = ( ( i_lfsr1_lo & 1 ) << 8 ) ^ o_lfsr1;
996 o_lfsr1 = p_css_tab4[o_lfsr1];
998 o_lfsr0 = ((((((( i_lfsr0 >> 8 ) ^ i_lfsr0 ) >> 1 )
999 ^ i_lfsr0 ) >> 3 ) ^ i_lfsr0 ) >> 7 );
1000 i_lfsr0 = ( i_lfsr0 >> 8 ) | ( o_lfsr0 << 24 );
1002 i_combined += ( o_lfsr0 ^ invert ) + o_lfsr1;
1003 k[i] = i_combined & 0xff;
1004 i_combined >>= 8;
1007 p_result[4] = k[4] ^ p_css_tab1[p_crypted[4]] ^ p_crypted[3];
1008 p_result[3] = k[3] ^ p_css_tab1[p_crypted[3]] ^ p_crypted[2];
1009 p_result[2] = k[2] ^ p_css_tab1[p_crypted[2]] ^ p_crypted[1];
1010 p_result[1] = k[1] ^ p_css_tab1[p_crypted[1]] ^ p_crypted[0];
1011 p_result[0] = k[0] ^ p_css_tab1[p_crypted[0]] ^ p_result[4];
1013 p_result[4] = k[4] ^ p_css_tab1[p_result[4]] ^ p_result[3];
1014 p_result[3] = k[3] ^ p_css_tab1[p_result[3]] ^ p_result[2];
1015 p_result[2] = k[2] ^ p_css_tab1[p_result[2]] ^ p_result[1];
1016 p_result[1] = k[1] ^ p_css_tab1[p_result[1]] ^ p_result[0];
1017 p_result[0] = k[0] ^ p_css_tab1[p_result[0]];
1019 return;
1022 /*****************************************************************************
1023 * player_keys: alternate DVD player keys
1024 *****************************************************************************
1025 * These player keys were generated using Frank A. Stevenson's PlayerKey
1026 * cracker. A copy of his article can be found here:
1027 * http://www-2.cs.cmu.edu/~dst/DeCSS/FrankStevenson/mail2.txt
1028 *****************************************************************************/
1029 static const dvd_key_t player_keys[] =
1031 { 0x01, 0xaf, 0xe3, 0x12, 0x80 },
1032 { 0x12, 0x11, 0xca, 0x04, 0x3b },
1033 { 0x14, 0x0c, 0x9e, 0xd0, 0x09 },
1034 { 0x14, 0x71, 0x35, 0xba, 0xe2 },
1035 { 0x1a, 0xa4, 0x33, 0x21, 0xa6 },
1036 { 0x26, 0xec, 0xc4, 0xa7, 0x4e },
1037 { 0x2c, 0xb2, 0xc1, 0x09, 0xee },
1038 { 0x2f, 0x25, 0x9e, 0x96, 0xdd },
1039 { 0x33, 0x2f, 0x49, 0x6c, 0xe0 },
1040 { 0x35, 0x5b, 0xc1, 0x31, 0x0f },
1041 { 0x36, 0x67, 0xb2, 0xe3, 0x85 },
1042 { 0x39, 0x3d, 0xf1, 0xf1, 0xbd },
1043 { 0x3b, 0x31, 0x34, 0x0d, 0x91 },
1044 { 0x45, 0xed, 0x28, 0xeb, 0xd3 },
1045 { 0x48, 0xb7, 0x6c, 0xce, 0x69 },
1046 { 0x4b, 0x65, 0x0d, 0xc1, 0xee },
1047 { 0x4c, 0xbb, 0xf5, 0x5b, 0x23 },
1048 { 0x51, 0x67, 0x67, 0xc5, 0xe0 },
1049 { 0x53, 0x94, 0xe1, 0x75, 0xbf },
1050 { 0x57, 0x2c, 0x8b, 0x31, 0xae },
1051 { 0x63, 0xdb, 0x4c, 0x5b, 0x4a },
1052 { 0x7b, 0x1e, 0x5e, 0x2b, 0x57 },
1053 { 0x85, 0xf3, 0x85, 0xa0, 0xe0 },
1054 { 0xab, 0x1e, 0xe7, 0x7b, 0x72 },
1055 { 0xab, 0x36, 0xe3, 0xeb, 0x76 },
1056 { 0xb1, 0xb8, 0xf9, 0x38, 0x03 },
1057 { 0xb8, 0x5d, 0xd8, 0x53, 0xbd },
1058 { 0xbf, 0x92, 0xc3, 0xb0, 0xe2 },
1059 { 0xcf, 0x1a, 0xb2, 0xf8, 0x0a },
1060 { 0xec, 0xa0, 0xcf, 0xb3, 0xff },
1061 { 0xfc, 0x95, 0xa9, 0x87, 0x35 }
1064 /*****************************************************************************
1065 * DecryptDiscKey
1066 *****************************************************************************
1067 * Decryption of the disc key with player keys: try to decrypt the disc key
1068 * from every position with every player key.
1069 * p_struct_disckey: the 2048 byte DVD_STRUCT_DISCKEY data
1070 * p_disc_key: result, the 5 byte disc key
1071 *****************************************************************************/
1072 static int DecryptDiscKey( dvdcss_t dvdcss, uint8_t const *p_struct_disckey,
1073 dvd_key_t p_disc_key )
1075 uint8_t p_verify[KEY_SIZE];
1076 unsigned int i, n = 0;
1078 /* Decrypt disc key with the above player keys */
1079 for( n = 0; n < sizeof(player_keys) / sizeof(dvd_key_t); n++ )
1081 PrintKey( dvdcss, "trying player key ", player_keys[n] );
1083 for( i = 1; i < 409; i++ )
1085 /* Check if player key n is the right key for position i. */
1086 DecryptKey( 0, player_keys[n], p_struct_disckey + 5 * i,
1087 p_disc_key );
1089 /* The first part in the struct_disckey block is the
1090 * 'disc key' encrypted with itself. Using this we
1091 * can check if we decrypted the correct key. */
1092 DecryptKey( 0, p_disc_key, p_struct_disckey, p_verify );
1094 /* If the position / player key pair worked then return. */
1095 if( memcmp( p_disc_key, p_verify, KEY_SIZE ) == 0 )
1097 return 0;
1102 /* Have tried all combinations of positions and keys,
1103 * and we still didn't succeed. */
1104 memset( p_disc_key, 0, KEY_SIZE );
1105 return -1;
1108 /*****************************************************************************
1109 * DecryptTitleKey
1110 *****************************************************************************
1111 * Decrypt the title key using the disc key.
1112 * p_disc_key: result, the 5 byte disc key
1113 * p_titlekey: the encrypted title key, gets overwritten by the decrypted key
1114 *****************************************************************************/
1115 static void DecryptTitleKey( dvd_key_t p_disc_key, dvd_key_t p_titlekey )
1117 DecryptKey( 0xff, p_disc_key, p_titlekey, p_titlekey );
1120 /*****************************************************************************
1121 * CrackDiscKey: brute force disc key
1122 * CSS hash reversal function designed by Frank Stevenson
1123 *****************************************************************************
1124 * This function uses a big amount of memory to crack the disc key from the
1125 * disc key hash, if player keys are not available.
1126 *****************************************************************************/
1127 #define K1TABLEWIDTH 10
1130 * Simple function to test if a candidate key produces the given hash
1132 static int investigate( unsigned char *hash, unsigned char *ckey )
1134 unsigned char key[KEY_SIZE];
1136 DecryptKey( 0, ckey, hash, key );
1138 return memcmp( key, ckey, KEY_SIZE );
1141 static int CrackDiscKey( dvdcss_t dvdcss, uint8_t *p_disc_key )
1143 unsigned char B[5] = { 0,0,0,0,0 }; /* Second Stage of mangle cipher */
1144 unsigned char C[5] = { 0,0,0,0,0 }; /* Output Stage of mangle cipher
1145 * IntermediateKey */
1146 unsigned char k[5] = { 0,0,0,0,0 }; /* Mangling cipher key
1147 * Also output from CSS( C ) */
1148 unsigned char out1[5]; /* five first output bytes of LFSR1 */
1149 unsigned char out2[5]; /* five first output bytes of LFSR2 */
1150 unsigned int lfsr1a; /* upper 9 bits of LFSR1 */
1151 unsigned int lfsr1b; /* lower 8 bits of LFSR1 */
1152 unsigned int tmp, tmp2, tmp3, tmp4,tmp5;
1153 int i,j;
1154 unsigned int nStepA; /* iterator for LFSR1 start state */
1155 unsigned int nStepB; /* iterator for possible B[0] */
1156 unsigned int nTry; /* iterator for K[1] possibilities */
1157 unsigned int nPossibleK1; /* #of possible K[1] values */
1158 unsigned char* K1table; /* Lookup table for possible K[1] */
1159 unsigned int* BigTable; /* LFSR2 startstate indexed by
1160 * 1,2,5 output byte */
1163 * Prepare tables for hash reversal
1166 /* initialize lookup tables for k[1] */
1167 K1table = malloc( 65536 * K1TABLEWIDTH );
1168 memset( K1table, 0 , 65536 * K1TABLEWIDTH );
1169 if( K1table == NULL )
1171 return -1;
1174 tmp = p_disc_key[0] ^ p_css_tab1[ p_disc_key[1] ];
1175 for( i = 0 ; i < 256 ; i++ ) /* k[1] */
1177 tmp2 = p_css_tab1[ tmp ^ i ]; /* p_css_tab1[ B[1] ]*/
1179 for( j = 0 ; j < 256 ; j++ ) /* B[0] */
1181 tmp3 = j ^ tmp2 ^ i; /* C[1] */
1182 tmp4 = K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) ]; /* count of entries here */
1183 tmp4++;
1185 if( tmp4 == K1TABLEWIDTH )
1187 print_debug( dvdcss, "Table disaster %d", tmp4 );
1190 if( tmp4 < K1TABLEWIDTH )
1192 K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) + tmp4 ] = i;
1194 K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) ] = tmp4;
1198 /* Initing our Really big table */
1199 BigTable = malloc( 16777216 * sizeof(int) );
1200 memset( BigTable, 0 , 16777216 * sizeof(int) );
1201 if( BigTable == NULL )
1203 return -1;
1206 tmp3 = 0;
1208 print_debug( dvdcss, "initializing the big table" );
1210 for( i = 0 ; i < 16777216 ; i++ )
1212 tmp = (( i + i ) & 0x1fffff0 ) | 0x8 | ( i & 0x7 );
1214 for( j = 0 ; j < 5 ; j++ )
1216 tmp2=((((((( tmp >> 3 ) ^ tmp ) >> 1 ) ^ tmp ) >> 8 )
1217 ^ tmp ) >> 5 ) & 0xff;
1218 tmp = ( tmp << 8) | tmp2;
1219 out2[j] = p_css_tab4[ tmp2 ];
1222 j = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4];
1223 BigTable[j] = i;
1227 * We are done initing, now reverse hash
1229 tmp5 = p_disc_key[0] ^ p_css_tab1[ p_disc_key[1] ];
1231 for( nStepA = 0 ; nStepA < 65536 ; nStepA ++ )
1233 lfsr1a = 0x100 | ( nStepA >> 8 );
1234 lfsr1b = nStepA & 0xff;
1236 /* Generate 5 first output bytes from lfsr1 */
1237 for( i = 0 ; i < 5 ; i++ )
1239 tmp = p_css_tab2[ lfsr1b ] ^ p_css_tab3[ lfsr1a ];
1240 lfsr1b = lfsr1a >> 1;
1241 lfsr1a = ((lfsr1a&1)<<8) ^ tmp;
1242 out1[ i ] = p_css_tab4[ tmp ];
1245 /* cumpute and cache some variables */
1246 C[0] = nStepA >> 8;
1247 C[1] = nStepA & 0xff;
1248 tmp = p_disc_key[3] ^ p_css_tab1[ p_disc_key[4] ];
1249 tmp2 = p_css_tab1[ p_disc_key[0] ];
1251 /* Search through all possible B[0] */
1252 for( nStepB = 0 ; nStepB < 256 ; nStepB++ )
1254 /* reverse parts of the mangling cipher */
1255 B[0] = nStepB;
1256 k[0] = p_css_tab1[ B[0] ] ^ C[0];
1257 B[4] = B[0] ^ k[0] ^ tmp2;
1258 k[4] = B[4] ^ tmp;
1259 nPossibleK1 = K1table[ K1TABLEWIDTH * (256 * B[0] + C[1]) ];
1261 /* Try out all possible values for k[1] */
1262 for( nTry = 0 ; nTry < nPossibleK1 ; nTry++ )
1264 k[1] = K1table[ K1TABLEWIDTH * (256 * B[0] + C[1]) + nTry + 1 ];
1265 B[1] = tmp5 ^ k[1];
1267 /* reconstruct output from LFSR2 */
1268 tmp3 = ( 0x100 + k[0] - out1[0] );
1269 out2[0] = tmp3 & 0xff;
1270 tmp3 = tmp3 & 0x100 ? 0x100 : 0xff;
1271 tmp3 = ( tmp3 + k[1] - out1[1] );
1272 out2[1] = tmp3 & 0xff;
1273 tmp3 = ( 0x100 + k[4] - out1[4] );
1274 out2[4] = tmp3 & 0xff; /* Can be 1 off */
1276 /* test first possible out2[4] */
1277 tmp4 = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4];
1278 tmp4 = BigTable[ tmp4 ];
1279 C[2] = tmp4 & 0xff;
1280 C[3] = ( tmp4 >> 8 ) & 0xff;
1281 C[4] = ( tmp4 >> 16 ) & 0xff;
1282 B[3] = p_css_tab1[ B[4] ] ^ k[4] ^ C[4];
1283 k[3] = p_disc_key[2] ^ p_css_tab1[ p_disc_key[3] ] ^ B[3];
1284 B[2] = p_css_tab1[ B[3] ] ^ k[3] ^ C[3];
1285 k[2] = p_disc_key[1] ^ p_css_tab1[ p_disc_key[2] ] ^ B[2];
1287 if( ( B[1] ^ p_css_tab1[ B[2] ] ^ k[ 2 ] ) == C[ 2 ] )
1289 if( ! investigate( &p_disc_key[0] , &C[0] ) )
1291 goto end;
1295 /* Test second possible out2[4] */
1296 out2[4] = ( out2[4] + 0xff ) & 0xff;
1297 tmp4 = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4];
1298 tmp4 = BigTable[ tmp4 ];
1299 C[2] = tmp4 & 0xff;
1300 C[3] = ( tmp4 >> 8 ) & 0xff;
1301 C[4] = ( tmp4 >> 16 ) & 0xff;
1302 B[3] = p_css_tab1[ B[4] ] ^ k[4] ^ C[4];
1303 k[3] = p_disc_key[2] ^ p_css_tab1[ p_disc_key[3] ] ^ B[3];
1304 B[2] = p_css_tab1[ B[3] ] ^ k[3] ^ C[3];
1305 k[2] = p_disc_key[1] ^ p_css_tab1[ p_disc_key[2] ] ^ B[2];
1307 if( ( B[1] ^ p_css_tab1[ B[2] ] ^ k[ 2 ] ) == C[ 2 ] )
1309 if( ! investigate( &p_disc_key[0] , &C[0] ) )
1311 goto end;
1318 end:
1320 memcpy( p_disc_key, &C[0], KEY_SIZE );
1322 free( K1table );
1323 free( BigTable );
1325 return 0;
1328 /*****************************************************************************
1329 * RecoverTitleKey: (title) key recovery from cipher and plain text
1330 * Function designed by Frank Stevenson
1331 *****************************************************************************
1332 * Called from Attack* which are in turn called by CrackTitleKey. Given
1333 * a guessed(?) plain text and the cipher text. Returns -1 on failure.
1334 *****************************************************************************/
1335 static int RecoverTitleKey( int i_start, uint8_t const *p_crypted,
1336 uint8_t const *p_decrypted,
1337 uint8_t const *p_sector_seed, uint8_t *p_key )
1339 uint8_t p_buffer[10];
1340 unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6;
1341 unsigned int i_try;
1342 unsigned int i_candidate;
1343 unsigned int i, j;
1344 int i_exit = -1;
1346 for( i = 0 ; i < 10 ; i++ )
1348 p_buffer[i] = p_css_tab1[p_crypted[i]] ^ p_decrypted[i];
1351 for( i_try = i_start ; i_try < 0x10000 ; i_try++ )
1353 i_t1 = i_try >> 8 | 0x100;
1354 i_t2 = i_try & 0xff;
1355 i_t3 = 0; /* not needed */
1356 i_t5 = 0;
1358 /* iterate cipher 4 times to reconstruct LFSR2 */
1359 for( i = 0 ; i < 4 ; i++ )
1361 /* advance LFSR1 normaly */
1362 i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1];
1363 i_t2 = i_t1 >> 1;
1364 i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4;
1365 i_t4 = p_css_tab5[i_t4];
1366 /* deduce i_t6 & i_t5 */
1367 i_t6 = p_buffer[i];
1368 if( i_t5 )
1370 i_t6 = ( i_t6 + 0xff ) & 0x0ff;
1372 if( i_t6 < i_t4 )
1374 i_t6 += 0x100;
1376 i_t6 -= i_t4;
1377 i_t5 += i_t6 + i_t4;
1378 i_t6 = p_css_tab4[ i_t6 ];
1379 /* feed / advance i_t3 / i_t5 */
1380 i_t3 = ( i_t3 << 8 ) | i_t6;
1381 i_t5 >>= 8;
1384 i_candidate = i_t3;
1386 /* iterate 6 more times to validate candidate key */
1387 for( ; i < 10 ; i++ )
1389 i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1];
1390 i_t2 = i_t1 >> 1;
1391 i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4;
1392 i_t4 = p_css_tab5[i_t4];
1393 i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^
1394 i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff;
1395 i_t3 = ( i_t3 << 8 ) | i_t6;
1396 i_t6 = p_css_tab4[i_t6];
1397 i_t5 += i_t6 + i_t4;
1398 if( ( i_t5 & 0xff ) != p_buffer[i] )
1400 break;
1403 i_t5 >>= 8;
1406 if( i == 10 )
1408 /* Do 4 backwards steps of iterating t3 to deduce initial state */
1409 i_t3 = i_candidate;
1410 for( i = 0 ; i < 4 ; i++ )
1412 i_t1 = i_t3 & 0xff;
1413 i_t3 = ( i_t3 >> 8 );
1414 /* easy to code, and fast enough bruteforce
1415 * search for byte shifted in */
1416 for( j = 0 ; j < 256 ; j++ )
1418 i_t3 = ( i_t3 & 0x1ffff ) | ( j << 17 );
1419 i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^
1420 i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff;
1421 if( i_t6 == i_t1 )
1423 break;
1428 i_t4 = ( i_t3 >> 1 ) - 4;
1429 for( i_t5 = 0 ; i_t5 < 8; i_t5++ )
1431 if( ( ( i_t4 + i_t5 ) * 2 + 8 - ( (i_t4 + i_t5 ) & 7 ) )
1432 == i_t3 )
1434 p_key[0] = i_try>>8;
1435 p_key[1] = i_try & 0xFF;
1436 p_key[2] = ( ( i_t4 + i_t5 ) >> 0 ) & 0xFF;
1437 p_key[3] = ( ( i_t4 + i_t5 ) >> 8 ) & 0xFF;
1438 p_key[4] = ( ( i_t4 + i_t5 ) >> 16 ) & 0xFF;
1439 i_exit = i_try + 1;
1445 if( i_exit >= 0 )
1447 p_key[0] ^= p_sector_seed[0];
1448 p_key[1] ^= p_sector_seed[1];
1449 p_key[2] ^= p_sector_seed[2];
1450 p_key[3] ^= p_sector_seed[3];
1451 p_key[4] ^= p_sector_seed[4];
1454 return i_exit;
1458 /******************************************************************************
1459 * Various pieces for the title crack engine.
1460 ******************************************************************************
1461 * The length of the PES packet is located at 0x12-0x13.
1462 * The the copyrigth protection bits are located at 0x14 (bits 0x20 and 0x10).
1463 * The data of the PES packet begins at 0x15 (if there isn't any PTS/DTS)
1464 * or at 0x?? if there are both PTS and DTS's.
1465 * The seed value used with the unscrambling key is the 5 bytes at 0x54-0x58.
1466 * The scrabled part of a sector begins at 0x80.
1467 *****************************************************************************/
1469 /* Statistics */
1470 static int i_tries = 0, i_success = 0;
1472 /*****************************************************************************
1473 * CrackTitleKey: try to crack title key from the contents of a VOB.
1474 *****************************************************************************
1475 * This function is called by _dvdcss_titlekey to find a title key, if we've
1476 * chosen to crack title key instead of decrypting it with the disc key.
1477 * The DVD should have been opened and be in an authenticated state.
1478 * i_pos is the starting sector, i_len is the maximum number of sectors to read
1479 *****************************************************************************/
1480 static int CrackTitleKey( dvdcss_t dvdcss, int i_pos, int i_len,
1481 dvd_key_t p_titlekey )
1483 uint8_t p_buf[ DVDCSS_BLOCK_SIZE ];
1484 const uint8_t p_packstart[4] = { 0x00, 0x00, 0x01, 0xba };
1485 int i_reads = 0;
1486 int i_encrypted = 0;
1487 int b_stop_scanning = 0;
1488 int b_read_error = 0;
1489 int i_ret;
1491 print_debug( dvdcss, "cracking title key at block %i", i_pos );
1493 i_tries = 0;
1494 i_success = 0;
1498 i_ret = dvdcss->pf_seek( dvdcss, i_pos );
1500 if( i_ret != i_pos )
1502 print_error( dvdcss, "seek failed" );
1505 i_ret = dvdcss_read( dvdcss, p_buf, 1, DVDCSS_NOFLAGS );
1507 /* Either we are at the end of the physical device or the auth
1508 * have failed / were not done and we got a read error. */
1509 if( i_ret <= 0 )
1511 if( i_ret == 0 )
1513 print_debug( dvdcss, "read returned 0 (end of device?)" );
1515 else if( !b_read_error )
1517 print_debug( dvdcss, "read error at block %i, resorting to "
1518 "secret arcanes to recover", i_pos );
1520 /* Reset the drive before trying to continue */
1521 _dvdcss_close( dvdcss );
1522 _dvdcss_open( dvdcss );
1524 b_read_error = 1;
1525 continue;
1527 break;
1530 /* Stop when we find a non MPEG stream block.
1531 * (We must have reached the end of the stream).
1532 * For now, allow all blocks that begin with a start code. */
1533 if( memcmp( p_buf, p_packstart, 3 ) )
1535 print_debug( dvdcss, "non MPEG block found at block %i "
1536 "(end of title)", i_pos );
1537 break;
1540 if( p_buf[0x0d] & 0x07 )
1541 print_debug( dvdcss, "stuffing in pack header" );
1543 /* PES_scrambling_control does not exist in a system_header,
1544 * a padding_stream or a private_stream2 (and others?). */
1545 if( p_buf[0x14] & 0x30 && ! ( p_buf[0x11] == 0xbb
1546 || p_buf[0x11] == 0xbe
1547 || p_buf[0x11] == 0xbf ) )
1549 i_encrypted++;
1551 if( AttackPattern(p_buf, i_reads, p_titlekey) > 0 )
1553 b_stop_scanning = 1;
1555 #if 0
1556 if( AttackPadding(p_buf, i_reads, p_titlekey) > 0 )
1558 b_stop_scanning = 1;
1560 #endif
1563 i_pos++;
1564 i_len--;
1565 i_reads++;
1567 /* Emit a progress indication now and then. */
1568 if( !( i_reads & 0xfff ) )
1570 print_debug( dvdcss, "at block %i, still cracking...", i_pos );
1573 /* Stop after 2000 blocks if we haven't seen any encrypted blocks. */
1574 if( i_reads >= 2000 && i_encrypted == 0 ) break;
1576 } while( !b_stop_scanning && i_len > 0);
1578 if( !b_stop_scanning )
1580 print_debug( dvdcss, "end of title reached" );
1583 /* Print some statistics. */
1584 print_debug( dvdcss, "successful attempts %d/%d, scrambled blocks %d/%d",
1585 i_success, i_tries, i_encrypted, i_reads );
1587 if( i_success > 0 /* b_stop_scanning */ )
1589 print_debug( dvdcss, "vts key initialized" );
1590 return 1;
1593 if( i_encrypted == 0 && i_reads > 0 )
1595 memset( p_titlekey, 0, KEY_SIZE );
1596 print_debug( dvdcss, "no scrambled sectors found" );
1597 return 0;
1600 memset( p_titlekey, 0, KEY_SIZE );
1601 return -1;
1605 /******************************************************************************
1606 * The original Ethan Hawke (DeCSSPlus) attack (modified).
1607 ******************************************************************************
1608 * Tries to find a repeating pattern just before the encrypted part starts.
1609 * Then it guesses that the plain text for first encrypted bytes are
1610 * a contiuation of that pattern.
1611 *****************************************************************************/
1612 static int AttackPattern( uint8_t const p_sec[ DVDCSS_BLOCK_SIZE ],
1613 int i_pos, uint8_t *p_key )
1615 unsigned int i_best_plen = 0;
1616 unsigned int i_best_p = 0;
1617 unsigned int i, j;
1619 /* For all cycle length from 2 to 48 */
1620 for( i = 2 ; i < 0x30 ; i++ )
1622 /* Find the number of bytes that repeats in cycles. */
1623 for( j = i + 1;
1624 j < 0x80 && ( p_sec[0x7F - (j%i)] == p_sec[0x7F - j] );
1625 j++ )
1627 /* We have found j repeating bytes with a cycle length i. */
1628 if( j > i_best_plen )
1630 i_best_plen = j;
1631 i_best_p = i;
1636 /* We need at most 10 plain text bytes?, so a make sure that we
1637 * have at least 20 repeated bytes and that they have cycled at
1638 * least one time. */
1639 if( ( i_best_plen > 3 ) && ( i_best_plen / i_best_p >= 2) )
1641 int res;
1643 i_tries++;
1644 memset( p_key, 0, KEY_SIZE );
1645 res = RecoverTitleKey( 0, &p_sec[0x80],
1646 &p_sec[ 0x80 - (i_best_plen / i_best_p) * i_best_p ],
1647 &p_sec[0x54] /* key_seed */, p_key );
1648 i_success += ( res >= 0 );
1649 #if 0
1650 if( res >= 0 )
1652 fprintf( stderr, "key is %02x:%02x:%02x:%02x:%02x ",
1653 p_key[0], p_key[1], p_key[2], p_key[3], p_key[4] );
1654 fprintf( stderr, "at block %5d pattern len %3d period %3d %s\n",
1655 i_pos, i_best_plen, i_best_p, (res>=0?"y":"n") );
1657 #endif
1658 return ( res >= 0 );
1661 return 0;
1665 #if 0
1666 /******************************************************************************
1667 * Encrypted Padding_stream attack.
1668 ******************************************************************************
1669 * DVD specifies that there must only be one type of data in every sector.
1670 * Every sector is one pack and so must obviously be 2048 bytes long.
1671 * For the last pice of video data before a VOBU boundary there might not
1672 * be exactly the right amount of data to fill a sector. Then one has to
1673 * pad the pack to 2048 bytes. For just a few bytes this is done in the
1674 * header but for any large amount you insert a PES packet from the
1675 * Padding stream. This looks like 0x00 00 01 be xx xx ff ff ...
1676 * where xx xx is the length of the padding stream.
1677 *****************************************************************************/
1678 static int AttackPadding( uint8_t const p_sec[ DVDCSS_BLOCK_SIZE ],
1679 int i_pos, uint8_t *p_key )
1681 unsigned int i_pes_length;
1682 /*static int i_tries = 0, i_success = 0;*/
1684 i_pes_length = (p_sec[0x12]<<8) | p_sec[0x13];
1686 /* Coverd by the test below but usfull for debuging. */
1687 if( i_pes_length == DVDCSS_BLOCK_SIZE - 0x14 ) return 0;
1689 /* There must be room for at least 4? bytes of padding stream,
1690 * and it must be encrypted.
1691 * sector size - pack/pes header - padding startcode - padding length */
1692 if( ( DVDCSS_BLOCK_SIZE - 0x14 - 4 - 2 - i_pes_length < 4 ) ||
1693 ( p_sec[0x14 + i_pes_length + 0] == 0x00 &&
1694 p_sec[0x14 + i_pes_length + 1] == 0x00 &&
1695 p_sec[0x14 + i_pes_length + 2] == 0x01 ) )
1697 fprintf( stderr, "plain %d %02x:%02x:%02x:%02x (type %02x sub %02x)\n",
1698 DVDCSS_BLOCK_SIZE - 0x14 - 4 - 2 - i_pes_length,
1699 p_sec[0x14 + i_pes_length + 0],
1700 p_sec[0x14 + i_pes_length + 1],
1701 p_sec[0x14 + i_pes_length + 2],
1702 p_sec[0x14 + i_pes_length + 3],
1703 p_sec[0x11], p_sec[0x17 + p_sec[0x16]]);
1704 return 0;
1707 /* If we are here we know that there is a where in the pack a
1708 encrypted PES header is (startcode + length). It's never more
1709 than two packets in the pack, so we 'know' the length. The
1710 plaintext at offset (0x14 + i_pes_length) will then be
1711 00 00 01 e0/bd/be xx xx, in the case of be the following bytes
1712 are also known. */
1714 /* An encrypted SPU PES packet with another encrypted PES packet following.
1715 Normaly if the following was a padding stream that would be in plain
1716 text. So it will be another SPU PES packet. */
1717 if( p_sec[0x11] == 0xbd &&
1718 p_sec[0x17 + p_sec[0x16]] >= 0x20 &&
1719 p_sec[0x17 + p_sec[0x16]] <= 0x3f )
1721 i_tries++;
1724 /* A Video PES packet with another encrypted PES packet following.
1725 * No reason execpt for time stamps to break the data into two packets.
1726 * So it's likely that the following PES packet is a padding stream. */
1727 if( p_sec[0x11] == 0xe0 )
1729 i_tries++;
1732 if( 1 )
1734 /*fprintf( stderr, "key is %02x:%02x:%02x:%02x:%02x ",
1735 p_key[0], p_key[1], p_key[2], p_key[3], p_key[4] );*/
1736 fprintf( stderr, "at block %5d padding len %4d "
1737 "type %02x sub %02x\n", i_pos, i_pes_length,
1738 p_sec[0x11], p_sec[0x17 + p_sec[0x16]]);
1741 return 0;
1743 #endif