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Diffstat (limited to 'src/css.c')
| -rw-r--r-- | src/css.c | 1756 |
1 files changed, 1756 insertions, 0 deletions
diff --git a/src/css.c b/src/css.c new file mode 100644 index 0000000..55cb8df --- /dev/null +++ b/src/css.c @@ -0,0 +1,1756 @@ +/***************************************************************************** + * css.c: Functions for DVD authentication and descrambling + ***************************************************************************** + * Copyright (C) 1999-2008 VideoLAN + * + * Authors: Stéphane Borel <stef@via.ecp.fr> + * Håkan Hjort <d95hjort@dtek.chalmers.se> + * + * based on: + * - css-auth by Derek Fawcus <derek@spider.com> + * - DVD CSS ioctls example program by Andrew T. Veliath <andrewtv@usa.net> + * - The Divide and conquer attack by Frank A. Stevenson <frank@funcom.com> + * (see http://www-2.cs.cmu.edu/~dst/DeCSS/FrankStevenson/index.html) + * - DeCSSPlus by Ethan Hawke + * - DecVOB + * see http://www.lemuria.org/DeCSS/ by Tom Vogt for more information. + * + * libdvdcss is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * libdvdcss is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with libdvdcss; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + *****************************************************************************/ + +/***************************************************************************** + * Preamble + *****************************************************************************/ +#include "config.h" + +#include <limits.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/types.h> +#ifdef HAVE_SYS_PARAM_H +# include <sys/param.h> +#endif +#ifdef HAVE_UNISTD_H +# include <unistd.h> +#endif +#include <fcntl.h> + +#include "dvdcss/dvdcss.h" + +#include "common.h" +#include "css.h" +#include "libdvdcss.h" +#include "csstables.h" +#include "ioctl.h" +#include "device.h" + +#define PSZ_KEY_SIZE (DVD_KEY_SIZE * 3) + +/***************************************************************************** + * Local prototypes + *****************************************************************************/ +static void PrintKey ( dvdcss_t, const char *, const uint8_t * ); + +static int GetBusKey ( dvdcss_t ); +static int GetASF ( dvdcss_t ); + +static void CryptKey ( int, int, const uint8_t *, uint8_t * ); +static void DecryptKey ( uint8_t, + const uint8_t *, const uint8_t *, uint8_t * ); + +static int DecryptDiscKey ( dvdcss_t, const uint8_t *, dvd_key ); +static int CrackDiscKey ( uint8_t * ); + +static void DecryptTitleKey ( dvd_key, dvd_key ); +static int RecoverTitleKey ( int, const uint8_t *, + const uint8_t *, const uint8_t *, uint8_t * ); +static int CrackTitleKey ( dvdcss_t, int, int, dvd_key ); + +static int AttackPattern ( const uint8_t[], uint8_t * ); +#if 0 +static int AttackPadding ( const uint8_t[] ); +#endif + +static int dvdcss_titlekey ( dvdcss_t, int, dvd_key ); + +/***************************************************************************** + * dvdcss_test: check if the disc is encrypted or not + ***************************************************************************** + * Return values: + * 1: DVD is scrambled but can be read + * 0: DVD is not scrambled and can be read + * -1: could not get "copyright" information + * -2: could not get RPC (Regional Playback Control) information + * (reading the disc might be possible) + * -3: drive is RPC-II, region is not set, and DVD is scrambled: the RPC + * scheme will prevent us from reading the scrambled data + *****************************************************************************/ +int dvdcss_test( dvdcss_t dvdcss ) +{ + const char *psz_type, *psz_rpc; + char psz_region[17]; + char *p_region = psz_region; + int i_ret, i_copyright, i_type, i_mask, i_rpc, i_region; + + i_ret = ioctl_ReadCopyright( dvdcss->i_fd, 0 /* i_layer */, &i_copyright ); + + if( i_ret < 0 ) + { +#ifdef _WIN32 + /* Maybe we didn't have enough privileges to read the copyright + * (see ioctl_ReadCopyright comments). + * Apparently, on unencrypted DVDs dvdcss_disckey() always fails, so + * we can check this as a workaround. */ + if( dvdcss_disckey( dvdcss ) < 0 ) + { + i_copyright = 0; + } + else + { + i_copyright = 1; + } +#else + /* Since it's the first ioctl we try to issue, we add a notice */ + print_error( dvdcss, "CSS error: could not get \"copyright\"" + " information, make sure there is a DVD in the drive," + " and that you have used the correct device node." ); + + return -1; +#endif /* _WIN32 */ + } + + print_debug( dvdcss, "disc reports copyright information 0x%x", + i_copyright ); + + i_ret = ioctl_ReportRPC( dvdcss->i_fd, &i_type, &i_mask, &i_rpc); + + if( i_ret < 0 ) + { + print_error( dvdcss, "CSS error: could not get RPC (Regional Playback " + "Control) status. Assuming RPC-I drive." ); + i_type = i_mask = i_rpc = 0; + } + + switch( i_rpc ) + { + case 0: psz_rpc = "RPC-I"; break; + case 1: psz_rpc = "RPC-II"; break; + default: psz_rpc = "unknown RPC (Regional Playback Control) scheme"; break; + } + + switch( i_type ) + { + case 0: psz_type = "no region code set"; break; + case 1: psz_type = "region code set"; break; + case 2: psz_type = "one region change remaining"; break; + case 3: psz_type = "region code set permanently"; break; + default: psz_type = "unknown status"; break; + } + + *p_region = '\0'; + for( i_region = 0; i_region < 8; i_region++ ) + { + if( !( i_mask & ( 1 << i_region ) ) ) + { + sprintf(p_region, " %d", i_region + 1); + p_region += 2; + } + } + + print_debug( dvdcss, "drive region(s)%s, region mask 0x%x, %s, %s", + psz_region, i_mask, psz_rpc, psz_type ); + + if( i_copyright && i_rpc == 1 && i_type == 0 ) + { + print_error( dvdcss, "CSS error: drive will prevent access to " + "scrambled data" ); + return -3; + } + + return i_copyright ? 1 : 0; +} + +/***************************************************************************** + * dvdcss_title: crack or decrypt the current title key if needed + ***************************************************************************** + * This function should only be called by dvdcss->pf_seek and should eventually + * not be external if possible. + *****************************************************************************/ +int dvdcss_title ( dvdcss_t dvdcss, int i_block ) +{ + struct dvd_title *p_title; + struct dvd_title *p_newtitle; + dvd_key p_title_key; + int i_fd, i_ret = -1, b_cache = 0; + + if( ! dvdcss->b_scrambled ) + { + return 0; + } + + /* Check if we've already cracked this key */ + p_title = dvdcss->p_titles; + while( p_title != NULL + && p_title->p_next != NULL + && p_title->p_next->i_startlb <= i_block ) + { + p_title = p_title->p_next; + } + + if( p_title != NULL + && p_title->i_startlb == i_block ) + { + /* We've already cracked this key, nothing to do */ + memcpy( dvdcss->css.p_title_key, p_title->p_key, sizeof(p_title->p_key) ); + return 0; + } + + /* Check whether the key is in our disk cache */ + if( dvdcss->psz_cachefile[0] ) + { + /* XXX: be careful, we use sprintf and not snprintf */ + sprintf( dvdcss->psz_block, "%." CACHE_FILENAME_LENGTH_STRING "x", + i_block ); + i_fd = open( dvdcss->psz_cachefile, O_RDONLY ); + b_cache = 1; + + if( i_fd >= 0 ) + { + char psz_key[PSZ_KEY_SIZE]; + unsigned int k0, k1, k2, k3, k4; + + psz_key[PSZ_KEY_SIZE - 1] = '\0'; + + if( read( i_fd, psz_key, PSZ_KEY_SIZE - 1 ) == PSZ_KEY_SIZE - 1 + && sscanf( psz_key, "%x:%x:%x:%x:%x", + &k0, &k1, &k2, &k3, &k4 ) == 5 ) + { + p_title_key[0] = k0; + p_title_key[1] = k1; + p_title_key[2] = k2; + p_title_key[3] = k3; + p_title_key[4] = k4; + PrintKey( dvdcss, "title key found in cache ", p_title_key ); + + /* Don't try to save it again */ + b_cache = 0; + i_ret = 1; + } + + close( i_fd ); + } + } + + /* Crack or decrypt Content Scrambling System (CSS) title key + * for current Video Title Set (VTS). */ + if( i_ret < 0 ) + { + i_ret = dvdcss_titlekey( dvdcss, i_block, p_title_key ); + + if( i_ret < 0 ) + { + print_error( dvdcss, "fatal error in Video Title Set (VTS) " + "Content Scrambling System (CSS) key" ); + return i_ret; + } + + if( i_ret == 0 ) + { + print_debug( dvdcss, "unencrypted title" ); + /* We cache this anyway, so we don't need to check again. */ + } + } + + /* Key is valid, we store it on disk. */ + if( dvdcss->psz_cachefile[0] && b_cache ) + { + i_fd = open( dvdcss->psz_cachefile, O_RDWR|O_CREAT, 0644 ); + if( i_fd >= 0 ) + { + char psz_key[PSZ_KEY_SIZE + 2]; + + sprintf( psz_key, "%02x:%02x:%02x:%02x:%02x\r\n", + p_title_key[0], p_title_key[1], p_title_key[2], + p_title_key[3], p_title_key[4] ); + + if( write( i_fd, psz_key, PSZ_KEY_SIZE + 1 ) < PSZ_KEY_SIZE + 1 ) + { + print_error( dvdcss, + "Error caching key on disk, continuing..\n" ); + } + close( i_fd ); + } + } + + /* Find our spot in the list */ + p_newtitle = NULL; + p_title = dvdcss->p_titles; + while( ( p_title != NULL ) && ( p_title->i_startlb < i_block ) ) + { + p_newtitle = p_title; + p_title = p_title->p_next; + } + + /* Save the found title */ + p_title = p_newtitle; + + /* Write in the new title and its key */ + p_newtitle = malloc( sizeof( *p_newtitle ) ); + if( p_newtitle == NULL ) + { + return -1; + } + p_newtitle->i_startlb = i_block; + memcpy( p_newtitle->p_key, p_title_key, DVD_KEY_SIZE ); + + /* Link it at the head of the (possibly empty) list */ + if( p_title == NULL ) + { + p_newtitle->p_next = dvdcss->p_titles; + dvdcss->p_titles = p_newtitle; + } + /* Link the new title inside the list */ + else + { + p_newtitle->p_next = p_title->p_next; + p_title->p_next = p_newtitle; + } + + memcpy( dvdcss->css.p_title_key, p_title_key, DVD_KEY_SIZE ); + return 0; +} + +/***************************************************************************** + * dvdcss_disckey: get disc key. + ***************************************************************************** + * This function should only be called if DVD ioctls are present. + * It will set dvdcss->i_method = DVDCSS_METHOD_TITLE if it fails to find + * a valid disc key. + * Two decryption methods are offered: + * -disc key hash crack, + * -decryption with player keys if they are available. + *****************************************************************************/ +int dvdcss_disckey( dvdcss_t dvdcss ) +{ + unsigned char p_buffer[ DVD_DISCKEY_SIZE ]; + dvd_key p_disc_key; + int i; + + if( GetBusKey( dvdcss ) < 0 ) + { + return -1; + } + + /* Get encrypted disc key */ + if( ioctl_ReadDiscKey( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 ) + { + print_error( dvdcss, "ioctl ReadDiscKey failed" ); + return -1; + } + + /* This should have invalidated the AGID and got us ASF=1. */ + if( GetASF( dvdcss ) != 1 ) + { + /* Region mismatch (or region not set) is the most likely source. */ + print_error( dvdcss, "authentication success flag (ASF) not 1 after " + "reading disc key (region mismatch?)" ); + ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + return -1; + } + + /* Shuffle disc key using bus key */ + for( i = 0 ; i < DVD_DISCKEY_SIZE ; i++ ) + { + p_buffer[i] ^= dvdcss->css.p_bus_key[4 - (i % DVD_KEY_SIZE)]; + } + + /* Decrypt disc key */ + switch( dvdcss->i_method ) + { + case DVDCSS_METHOD_KEY: + + /* Decrypt disc key with player key. */ + PrintKey( dvdcss, "decrypting disc key ", p_buffer ); + if( ! DecryptDiscKey( dvdcss, p_buffer, p_disc_key ) ) + { + PrintKey( dvdcss, "decrypted disc key is ", p_disc_key ); + break; + } + print_debug( dvdcss, "failed to decrypt the disc key, " + "faulty drive/kernel? " + "cracking title keys instead" ); + + /* Fallback, but not to DISC as the disc key might be faulty */ + memset( p_disc_key, 0, DVD_KEY_SIZE ); + dvdcss->i_method = DVDCSS_METHOD_TITLE; + break; + + case DVDCSS_METHOD_DISC: + + /* Crack Disc key to be able to use it */ + memcpy( p_disc_key, p_buffer, DVD_KEY_SIZE ); + PrintKey( dvdcss, "cracking disc key ", p_disc_key ); + if( ! CrackDiscKey( p_disc_key ) ) + { + PrintKey( dvdcss, "cracked disc key is ", p_disc_key ); + break; + } + print_debug( dvdcss, "failed to crack the disc key" ); + memset( p_disc_key, 0, DVD_KEY_SIZE ); + dvdcss->i_method = DVDCSS_METHOD_TITLE; + break; + + default: + + print_debug( dvdcss, "disc key does not need to be decrypted" ); + memset( p_disc_key, 0, DVD_KEY_SIZE ); + break; + } + + memcpy( dvdcss->css.p_disc_key, p_disc_key, DVD_KEY_SIZE ); + + return 0; +} + + +/***************************************************************************** + * dvdcss_titlekey: get title key. + *****************************************************************************/ +static int dvdcss_titlekey( dvdcss_t dvdcss, int i_pos, dvd_key p_title_key ) +{ + static uint8_t p_garbage[ DVDCSS_BLOCK_SIZE ]; /* we never read it back */ + uint8_t p_key[DVD_KEY_SIZE]; + int i, i_ret = 0; + + if( dvdcss->b_ioctls && ( dvdcss->i_method == DVDCSS_METHOD_KEY || + dvdcss->i_method == DVDCSS_METHOD_DISC ) ) + { + /* We have a decrypted Disc key and the ioctls are available, + * read the title key and decrypt it. + */ + + print_debug( dvdcss, "getting title key at block %i the classic way", + i_pos ); + + /* We need to authenticate again every time to get a new session key */ + if( GetBusKey( dvdcss ) < 0 ) + { + i_ret = -1; + } + + /* Get encrypted title key */ + if( ioctl_ReadTitleKey( dvdcss->i_fd, &dvdcss->css.i_agid, + i_pos, p_key ) < 0 ) + { + print_debug( dvdcss, + "ioctl ReadTitleKey failed (region mismatch?)" ); + i_ret = -1; + } + + /* Test ASF, it will be reset to 0 if we got a Region error */ + switch( GetASF( dvdcss ) ) + { + case -1: + /* An error getting the ASF status, something must be wrong. */ + print_debug( dvdcss, "lost authentication success flag (ASF), requesting title key" ); + ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + i_ret = -1; + break; + + case 0: + /* This might either be a title that has no key, + * or we encountered a region error. */ + print_debug( dvdcss, "lost authentication success flag (ASF), requesting title key" ); + break; + + case 1: + /* Drive status is OK. */ + /* If the title key request failed, but we did not lose ASF, + * we might still have the AGID. Other code assumes that we + * will not after this so invalidate it(?). */ + if( i_ret < 0 ) + { + ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + } + break; + } + + if( !( i_ret < 0 ) ) + { + /* Decrypt title key using the bus key */ + for( i = 0 ; i < DVD_KEY_SIZE ; i++ ) + { + p_key[i] ^= dvdcss->css.p_bus_key[4 - (i % DVD_KEY_SIZE)]; + } + + /* If p_key is all zero then there really wasn't any key present + * even though we got to read it without an error. */ + if( !( p_key[0] | p_key[1] | p_key[2] | p_key[3] | p_key[4] ) ) + { + i_ret = 0; + } + else + { + PrintKey( dvdcss, "initial disc key ", dvdcss->css.p_disc_key ); + DecryptTitleKey( dvdcss->css.p_disc_key, p_key ); + PrintKey( dvdcss, "decrypted title key ", p_key ); + i_ret = 1; + } + + /* All went well either there wasn't a key or we have it now. */ + memcpy( p_title_key, p_key, DVD_KEY_SIZE ); + PrintKey( dvdcss, "title key is ", p_title_key ); + + return i_ret; + } + + /* The title key request failed */ + print_debug( dvdcss, "resetting drive and cracking title key" ); + + /* Read an unscrambled sector and reset the drive */ + dvdcss->pf_seek( dvdcss, 0 ); + dvdcss->pf_read( dvdcss, p_garbage, 1 ); + dvdcss->pf_seek( dvdcss, 0 ); + dvdcss_disckey( dvdcss ); + + /* Fallback */ + } + + /* METHOD is TITLE, we can't use the ioctls or requesting the title key + * failed above. For these cases we try to crack the key instead. */ + + /* For now, the read limit is 9GB / 2048 = 4718592 sectors. */ + i_ret = CrackTitleKey( dvdcss, i_pos, 4718592, p_key ); + + memcpy( p_title_key, p_key, DVD_KEY_SIZE ); + PrintKey( dvdcss, "title key is ", p_title_key ); + + return i_ret; +} + +/***************************************************************************** + * dvdcss_unscramble: does the actual descrambling of data + ***************************************************************************** + * sec: sector to unscramble + * key: title key for this sector + *****************************************************************************/ +int dvdcss_unscramble( dvd_key p_key, uint8_t *p_sec ) +{ + unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6; + uint8_t *p_end = p_sec + DVDCSS_BLOCK_SIZE; + + /* PES_scrambling_control */ + if( !(p_sec[0x14] & 0x30) ) + { + return 0; + } + + i_t1 = (p_key[0] ^ p_sec[0x54]) | 0x100; + i_t2 = p_key[1] ^ p_sec[0x55]; + i_t3 = (p_key[2] | (p_key[3] << 8) | + (p_key[4] << 16)) ^ (p_sec[0x56] | + (p_sec[0x57] << 8) | (p_sec[0x58] << 16)); + i_t4 = i_t3 & 7; + i_t3 = i_t3 * 2 + 8 - i_t4; + p_sec += 0x80; + i_t5 = 0; + + while( p_sec != p_end ) + { + i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1]; + i_t2 = i_t1>>1; + i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4; + i_t4 = p_css_tab5[i_t4]; + i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^ + i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff; + i_t3 = (i_t3 << 8 ) | i_t6; + i_t6 = p_css_tab4[i_t6]; + i_t5 += i_t6 + i_t4; + *p_sec = p_css_tab1[*p_sec] ^ ( i_t5 & 0xff ); + p_sec++; + i_t5 >>= 8; + } + + return 0; +} + +/* Following functions are local */ + +/***************************************************************************** + * GetBusKey: Go through the Content Scrambling System (CSS) authentication process + ***************************************************************************** + * It simulates the mutual authentication between logical unit and host, + * and stops when a session key (called bus key) has been established. + * Always do the full auth sequence. Some drives seem to lie and always + * respond with ASF=1. For instance the old DVD-ROMs on Compaq Armada say + * that ASF=1 from the start and then later fail with a 'read of scrambled + * block without authentication' error. + *****************************************************************************/ +static int GetBusKey( dvdcss_t dvdcss ) +{ + uint8_t p_buffer[10]; + uint8_t p_challenge[2 * DVD_KEY_SIZE]; + dvd_key p_key1; + dvd_key p_key2; + dvd_key p_key_check; + uint8_t i_variant = 0; + int i_ret = -1; + int i; + + print_debug( dvdcss, "requesting authentication grant ID (AGID)" ); + i_ret = ioctl_ReportAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + + /* We might have to reset hung authentication processes in the drive + * by invalidating the corresponding authentication grant ID (AGID)'. + * As long as we haven't got an AGID, invalidate one (in sequence) + * and try again. */ + for( i = 0; i_ret == -1 && i < 4 ; ++i ) + { + print_debug( dvdcss, "ioctl ReportAgid failed, invalidating " + "authentication grant ID (AGID) %d", i ); + + /* This is really _not good_, should be handled by the OS. + * Invalidating an AGID could make another process fail somewhere + * in its authentication process. */ + dvdcss->css.i_agid = i; + ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + + print_debug( dvdcss, "requesting authentication grant ID (AGID)" ); + i_ret = ioctl_ReportAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + } + + /* Unable to authenticate without AGID */ + if( i_ret == -1 ) + { + print_error( dvdcss, "ioctl ReportAgid failed, fatal" ); + return -1; + } + + /* Setup a challenge, any values should work */ + for( i = 0 ; i < 10; ++i ) + { + p_challenge[i] = i; + } + + /* Get challenge from host */ + for( i = 0 ; i < 10 ; ++i ) + { + p_buffer[9-i] = p_challenge[i]; + } + + /* Send challenge to LU */ + if( ioctl_SendChallenge( dvdcss->i_fd, + &dvdcss->css.i_agid, p_buffer ) < 0 ) + { + print_error( dvdcss, "ioctl SendChallenge failed" ); + ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + return -1; + } + + /* Get key1 from LU */ + if( ioctl_ReportKey1( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0) + { + print_error( dvdcss, "ioctl ReportKey1 failed" ); + ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + return -1; + } + + /* Send key1 to host */ + for( i = 0 ; i < DVD_KEY_SIZE ; i++ ) + { + p_key1[i] = p_buffer[4-i]; + } + + for( i = 0 ; i < 32 ; ++i ) + { + CryptKey( 0, i, p_challenge, p_key_check ); + + if( memcmp( p_key_check, p_key1, DVD_KEY_SIZE ) == 0 ) + { + print_debug( dvdcss, "drive authenticated, using variant %d", i ); + i_variant = i; + break; + } + } + + if( i == 32 ) + { + print_error( dvdcss, "drive would not authenticate" ); + ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + return -1; + } + + /* Get challenge from LU */ + if( ioctl_ReportChallenge( dvdcss->i_fd, + &dvdcss->css.i_agid, p_buffer ) < 0 ) + { + print_error( dvdcss, "ioctl ReportKeyChallenge failed" ); + ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + return -1; + } + + /* Send challenge to host */ + for( i = 0 ; i < 10 ; ++i ) + { + p_challenge[i] = p_buffer[9-i]; + } + + CryptKey( 1, i_variant, p_challenge, p_key2 ); + + /* Get key2 from host */ + for( i = 0 ; i < DVD_KEY_SIZE ; ++i ) + { + p_buffer[4-i] = p_key2[i]; + } + + /* Send key2 to LU */ + if( ioctl_SendKey2( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 ) + { + print_error( dvdcss, "ioctl SendKey2 failed" ); + ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid ); + return -1; + } + + /* The drive has accepted us as authentic. */ + print_debug( dvdcss, "authentication established" ); + + memcpy( p_challenge, p_key1, DVD_KEY_SIZE ); + memcpy( p_challenge + DVD_KEY_SIZE, p_key2, DVD_KEY_SIZE ); + + CryptKey( 2, i_variant, p_challenge, dvdcss->css.p_bus_key ); + + return 0; +} + +/***************************************************************************** + * PrintKey: debug function that dumps a key value + *****************************************************************************/ +static void PrintKey( dvdcss_t dvdcss, const char *prefix, const uint8_t *data ) +{ + print_debug( dvdcss, "%s%02x:%02x:%02x:%02x:%02x", prefix, + data[0], data[1], data[2], data[3], data[4] ); +} + +/***************************************************************************** + * GetASF: Get authentication success flag (ASF) + ***************************************************************************** + * Returns: + * -1 on ioctl error, + * 0 if the device needs to be authenticated, + * 1 either. + *****************************************************************************/ +static int GetASF( dvdcss_t dvdcss ) +{ + int i_asf = 0; + + if( ioctl_ReportASF( dvdcss->i_fd, &i_asf ) != 0 ) + { + /* The ioctl process has failed */ + print_error( dvdcss, "GetASF fatal error" ); + return -1; + } + + if( i_asf ) + { + print_debug( dvdcss, "authentication success flag set, ASF=1" ); + } + else + { + print_debug( dvdcss, "authentication success flag not set, ASF=0" ); + } + + return i_asf; +} + +/***************************************************************************** + * CryptKey: shuffle bits and decrypt keys. + ***************************************************************************** + * Used during authentication and disc key negotiation in GetBusKey. + * i_key_type: 0->key1, 1->key2, 2->buskey. + * i_variant: between 0 and 31. + *****************************************************************************/ +static void CryptKey( int i_key_type, int i_variant, + const uint8_t *p_challenge, uint8_t *p_key ) +{ + /* Permutation table for challenge */ + static const uint8_t pp_perm_challenge[3][10] = + { { 1, 3, 0, 7, 5, 2, 9, 6, 4, 8 }, + { 6, 1, 9, 3, 8, 5, 7, 4, 0, 2 }, + { 4, 0, 3, 5, 7, 2, 8, 6, 1, 9 } }; + + /* Permutation table for variant table for key2 and buskey */ + static const uint8_t pp_perm_variant[2][32] = + { { 0x0a, 0x08, 0x0e, 0x0c, 0x0b, 0x09, 0x0f, 0x0d, + 0x1a, 0x18, 0x1e, 0x1c, 0x1b, 0x19, 0x1f, 0x1d, + 0x02, 0x00, 0x06, 0x04, 0x03, 0x01, 0x07, 0x05, + 0x12, 0x10, 0x16, 0x14, 0x13, 0x11, 0x17, 0x15 }, + { 0x12, 0x1a, 0x16, 0x1e, 0x02, 0x0a, 0x06, 0x0e, + 0x10, 0x18, 0x14, 0x1c, 0x00, 0x08, 0x04, 0x0c, + 0x13, 0x1b, 0x17, 0x1f, 0x03, 0x0b, 0x07, 0x0f, + 0x11, 0x19, 0x15, 0x1d, 0x01, 0x09, 0x05, 0x0d } }; + + static const uint8_t p_variants[32] = + { 0xB7, 0x74, 0x85, 0xD0, 0xCC, 0xDB, 0xCA, 0x73, + 0x03, 0xFE, 0x31, 0x03, 0x52, 0xE0, 0xB7, 0x42, + 0x63, 0x16, 0xF2, 0x2A, 0x79, 0x52, 0xFF, 0x1B, + 0x7A, 0x11, 0xCA, 0x1A, 0x9B, 0x40, 0xAD, 0x01 }; + + /* The "secret" key */ + static const uint8_t p_secret[5] = { 0x55, 0xD6, 0xC4, 0xC5, 0x28 }; + + uint8_t p_bits[30], p_scratch[10], p_tmp1[5], p_tmp2[5]; + uint8_t i_lfsr0_o; /* 1 bit used */ + uint8_t i_lfsr1_o; /* 1 bit used */ + uint8_t i_css_variant, i_cse, i_index, i_combined, i_carry; + uint8_t i_val = 0; + uint32_t i_lfsr0, i_lfsr1; + int i_term = 0; + int i_bit; + int i; + + for (i = 9; i >= 0; --i) + p_scratch[i] = p_challenge[pp_perm_challenge[i_key_type][i]]; + + i_css_variant = ( i_key_type == 0 ) ? i_variant : + pp_perm_variant[i_key_type-1][i_variant]; + + /* + * This encryption engine implements one of 32 variations + * one the same theme depending upon the choice in the + * variant parameter (0 - 31). + * + * The algorithm itself manipulates a 40 bit input into + * a 40 bit output. + * The parameter 'input' is 80 bits. It consists of + * the 40 bit input value that is to be encrypted followed + * by a 40 bit seed value for the pseudo random number + * generators. + */ + + /* Feed the secret into the input values such that + * we alter the seed to the LFSR's used above, then + * generate the bits to play with. + */ + for( i = 5 ; --i >= 0 ; ) + { + p_tmp1[i] = p_scratch[5 + i] ^ p_secret[i] ^ p_crypt_tab2[i]; + } + + /* + * We use two LFSR's (seeded from some of the input data bytes) to + * generate two streams of pseudo-random bits. These two bit streams + * are then combined by simply adding with carry to generate a final + * sequence of pseudo-random bits which is stored in the buffer that + * 'output' points to the end of - len is the size of this buffer. + * + * The first LFSR is of degree 25, and has a polynomial of: + * x^13 + x^5 + x^4 + x^1 + 1 + * + * The second LFSR is of degree 17, and has a (primitive) polynomial of: + * x^15 + x^1 + 1 + * + * I don't know if these polynomials are primitive modulo 2, and thus + * represent maximal-period LFSR's. + * + * + * Note that we take the output of each LFSR from the new shifted in + * bit, not the old shifted out bit. Thus for ease of use the LFSR's + * are implemented in bit reversed order. + * + */ + + /* In order to ensure that the LFSR works we need to ensure that the + * initial values are non-zero. Thus when we initialize them from + * the seed, we ensure that a bit is set. + */ + i_lfsr0 = ( p_tmp1[0] << 17 ) | ( p_tmp1[1] << 9 ) | + (( p_tmp1[2] & ~7 ) << 1 ) | 8 | ( p_tmp1[2] & 7 ); + i_lfsr1 = ( p_tmp1[3] << 9 ) | 0x100 | p_tmp1[4]; + + i_index = sizeof(p_bits); + i_carry = 0; + + do + { + for( i_bit = 0, i_val = 0 ; i_bit < 8 ; ++i_bit ) + { + + i_lfsr0_o = ( ( i_lfsr0 >> 24 ) ^ ( i_lfsr0 >> 21 ) ^ + ( i_lfsr0 >> 20 ) ^ ( i_lfsr0 >> 12 ) ) & 1; + i_lfsr0 = ( i_lfsr0 << 1 ) | i_lfsr0_o; + + i_lfsr1_o = ( ( i_lfsr1 >> 16 ) ^ ( i_lfsr1 >> 2 ) ) & 1; + i_lfsr1 = ( i_lfsr1 << 1 ) | i_lfsr1_o; + + i_combined = !i_lfsr1_o + i_carry + !i_lfsr0_o; + /* taking bit 1 */ + i_carry = ( i_combined >> 1 ) & 1; + i_val |= ( i_combined & 1 ) << i_bit; + } + + p_bits[--i_index] = i_val; + } while( i_index > 0 ); + + /* This term is used throughout the following to + * select one of 32 different variations on the + * algorithm. + */ + i_cse = p_variants[i_css_variant] ^ p_crypt_tab2[i_css_variant]; + + /* Now the actual blocks doing the encryption. Each + * of these works on 40 bits at a time and are quite + * similar. + */ + i_index = 0; + for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_scratch[i] ) + { + i_index = p_bits[25 + i] ^ p_scratch[i]; + i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse; + + p_tmp1[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term; + } + p_tmp1[4] ^= p_tmp1[0]; + + for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] ) + { + i_index = p_bits[20 + i] ^ p_tmp1[i]; + i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse; + + p_tmp2[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term; + } + p_tmp2[4] ^= p_tmp2[0]; + + for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp2[i] ) + { + i_index = p_bits[15 + i] ^ p_tmp2[i]; + i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse; + i_index = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term; + + p_tmp1[i] = p_crypt_tab0[i_index] ^ p_crypt_tab2[i_index]; + } + p_tmp1[4] ^= p_tmp1[0]; + + for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] ) + { + i_index = p_bits[10 + i] ^ p_tmp1[i]; + i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse; + + i_index = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term; + + p_tmp2[i] = p_crypt_tab0[i_index] ^ p_crypt_tab2[i_index]; + } + p_tmp2[4] ^= p_tmp2[0]; + + for( i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp2[i] ) + { + i_index = p_bits[5 + i] ^ p_tmp2[i]; + i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse; + + p_tmp1[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term; + } + p_tmp1[4] ^= p_tmp1[0]; + + for(i = 5, i_term = 0 ; --i >= 0 ; i_term = p_tmp1[i] ) + { + i_index = p_bits[i] ^ p_tmp1[i]; + i_index = p_crypt_tab1[i_index] ^ ~p_crypt_tab2[i_index] ^ i_cse; + + p_key[i] = p_crypt_tab2[i_index] ^ p_crypt_tab3[i_index] ^ i_term; + } + + return; +} + +/***************************************************************************** + * DecryptKey: decrypt p_crypted with p_key. + ***************************************************************************** + * Used to decrypt the disc key, with a player key, after requesting it + * in dvdcss_disckey and to decrypt title keys, with a disc key, requested + * in dvdcss_titlekey. + * The player keys and the resulting disc key are only used as KEKs + * (key encryption keys). + * Decryption is slightly dependent on the type of key: + * -for disc key, invert is 0x00, + * -for title key, invert if 0xff. + *****************************************************************************/ +static void DecryptKey( uint8_t invert, const uint8_t *p_key, + const uint8_t *p_crypted, uint8_t *p_result ) +{ + unsigned int i_lfsr1_lo; + unsigned int i_lfsr1_hi; + unsigned int i_lfsr0; + unsigned int i_combined; + uint8_t o_lfsr0; + uint8_t o_lfsr1; + uint8_t k[5]; + int i; + + i_lfsr1_lo = p_key[0] | 0x100; + i_lfsr1_hi = p_key[1]; + + i_lfsr0 = ( ( p_key[4] << 17 ) + | ( p_key[3] << 9 ) + | ( p_key[2] << 1 ) ) + + 8 - ( p_key[2] & 7 ); + i_lfsr0 = ( p_css_tab4[i_lfsr0 & 0xff] << 24 ) | + ( p_css_tab4[( i_lfsr0 >> 8 ) & 0xff] << 16 ) | + ( p_css_tab4[( i_lfsr0 >> 16 ) & 0xff] << 8 ) | + p_css_tab4[( i_lfsr0 >> 24 ) & 0xff]; + + i_combined = 0; + for( i = 0 ; i < DVD_KEY_SIZE ; ++i ) + { + o_lfsr1 = p_css_tab2[i_lfsr1_hi] ^ p_css_tab3[i_lfsr1_lo]; + i_lfsr1_hi = i_lfsr1_lo >> 1; + i_lfsr1_lo = ( ( i_lfsr1_lo & 1 ) << 8 ) ^ o_lfsr1; + o_lfsr1 = p_css_tab4[o_lfsr1]; + + o_lfsr0 = ((((((( i_lfsr0 >> 8 ) ^ i_lfsr0 ) >> 1 ) + ^ i_lfsr0 ) >> 3 ) ^ i_lfsr0 ) >> 7 ); + i_lfsr0 = ( i_lfsr0 >> 8 ) | ( o_lfsr0 << 24 ); + + i_combined += ( o_lfsr0 ^ invert ) + o_lfsr1; + k[i] = i_combined & 0xff; + i_combined >>= 8; + } + + p_result[4] = k[4] ^ p_css_tab1[p_crypted[4]] ^ p_crypted[3]; + p_result[3] = k[3] ^ p_css_tab1[p_crypted[3]] ^ p_crypted[2]; + p_result[2] = k[2] ^ p_css_tab1[p_crypted[2]] ^ p_crypted[1]; + p_result[1] = k[1] ^ p_css_tab1[p_crypted[1]] ^ p_crypted[0]; + p_result[0] = k[0] ^ p_css_tab1[p_crypted[0]] ^ p_result[4]; + + p_result[4] = k[4] ^ p_css_tab1[p_result[4]] ^ p_result[3]; + p_result[3] = k[3] ^ p_css_tab1[p_result[3]] ^ p_result[2]; + p_result[2] = k[2] ^ p_css_tab1[p_result[2]] ^ p_result[1]; + p_result[1] = k[1] ^ p_css_tab1[p_result[1]] ^ p_result[0]; + p_result[0] = k[0] ^ p_css_tab1[p_result[0]]; + + return; +} + +/***************************************************************************** + * player_keys: alternate DVD player keys + ***************************************************************************** + * These player keys were generated using Frank A. Stevenson's PlayerKey + * cracker. A copy of his article can be found here: + * http://www-2.cs.cmu.edu/~dst/DeCSS/FrankStevenson/mail2.txt + *****************************************************************************/ +static const dvd_key player_keys[] = +{ + { 0x01, 0xaf, 0xe3, 0x12, 0x80 }, + { 0x12, 0x11, 0xca, 0x04, 0x3b }, + { 0x14, 0x0c, 0x9e, 0xd0, 0x09 }, + { 0x14, 0x71, 0x35, 0xba, 0xe2 }, + { 0x1a, 0xa4, 0x33, 0x21, 0xa6 }, + { 0x26, 0xec, 0xc4, 0xa7, 0x4e }, + { 0x2c, 0xb2, 0xc1, 0x09, 0xee }, + { 0x2f, 0x25, 0x9e, 0x96, 0xdd }, + { 0x33, 0x2f, 0x49, 0x6c, 0xe0 }, + { 0x35, 0x5b, 0xc1, 0x31, 0x0f }, + { 0x36, 0x67, 0xb2, 0xe3, 0x85 }, + { 0x39, 0x3d, 0xf1, 0xf1, 0xbd }, + { 0x3b, 0x31, 0x34, 0x0d, 0x91 }, + { 0x45, 0xed, 0x28, 0xeb, 0xd3 }, + { 0x48, 0xb7, 0x6c, 0xce, 0x69 }, + { 0x4b, 0x65, 0x0d, 0xc1, 0xee }, + { 0x4c, 0xbb, 0xf5, 0x5b, 0x23 }, + { 0x51, 0x67, 0x67, 0xc5, 0xe0 }, + { 0x53, 0x94, 0xe1, 0x75, 0xbf }, + { 0x57, 0x2c, 0x8b, 0x31, 0xae }, + { 0x63, 0xdb, 0x4c, 0x5b, 0x4a }, + { 0x7b, 0x1e, 0x5e, 0x2b, 0x57 }, + { 0x85, 0xf3, 0x85, 0xa0, 0xe0 }, + { 0xab, 0x1e, 0xe7, 0x7b, 0x72 }, + { 0xab, 0x36, 0xe3, 0xeb, 0x76 }, + { 0xb1, 0xb8, 0xf9, 0x38, 0x03 }, + { 0xb8, 0x5d, 0xd8, 0x53, 0xbd }, + { 0xbf, 0x92, 0xc3, 0xb0, 0xe2 }, + { 0xcf, 0x1a, 0xb2, 0xf8, 0x0a }, + { 0xec, 0xa0, 0xcf, 0xb3, 0xff }, + { 0xfc, 0x95, 0xa9, 0x87, 0x35 } +}; + +/***************************************************************************** + * DecryptDiscKey + ***************************************************************************** + * Decryption of the disc key with player keys: try to decrypt the disc key + * from every position with every player key. + * p_struct_disckey: the 2048 byte DVD_STRUCT_DISCKEY data + * p_disc_key: result, the 5 byte disc key + *****************************************************************************/ +static int DecryptDiscKey( dvdcss_t dvdcss, const uint8_t *p_struct_disckey, + dvd_key p_disc_key ) +{ + uint8_t p_verify[DVD_KEY_SIZE]; + unsigned int i, n = 0; + + /* Decrypt disc key with the above player keys */ + for( n = 0; n < sizeof(player_keys) / sizeof(*player_keys); n++ ) + { + PrintKey( dvdcss, "trying player key ", player_keys[n] ); + + for( i = 1; i < 409; i++ ) + { + /* Check if player key n is the right key for position i. */ + DecryptKey( 0, player_keys[n], p_struct_disckey + 5 * i, + p_disc_key ); + + /* The first part in the struct_disckey block is the + * 'disc key' encrypted with itself. Using this we + * can check if we decrypted the correct key. */ + DecryptKey( 0, p_disc_key, p_struct_disckey, p_verify ); + + /* If the position / player key pair worked then return. */ + if( memcmp( p_disc_key, p_verify, DVD_KEY_SIZE ) == 0 ) + { + return 0; + } + } + } + + /* Have tried all combinations of positions and keys, + * and we still didn't succeed. */ + memset( p_disc_key, 0, DVD_KEY_SIZE ); + return -1; +} + +/***************************************************************************** + * DecryptTitleKey + ***************************************************************************** + * Decrypt the title key using the disc key. + * p_disc_key: result, the 5 byte disc key + * p_titlekey: the encrypted title key, gets overwritten by the decrypted key + *****************************************************************************/ +static void DecryptTitleKey( dvd_key p_disc_key, dvd_key p_titlekey ) +{ + DecryptKey( 0xff, p_disc_key, p_titlekey, p_titlekey ); +} + +/***************************************************************************** + * CrackDiscKey: brute force disc key + * CSS hash reversal function designed by Frank Stevenson + ***************************************************************************** + * This function uses a big amount of memory to crack the disc key from the + * disc key hash, if player keys are not available. + *****************************************************************************/ +#define K1TABLESIZE 65536 +#define K1TABLEWIDTH 10 + +#define BIGTABLESIZE 16777216 + +/* + * Simple function to test if a candidate key produces the given hash + */ +static int investigate( unsigned char *hash, unsigned char *ckey ) +{ + unsigned char key[DVD_KEY_SIZE]; + + DecryptKey( 0, ckey, hash, key ); + + return memcmp( key, ckey, DVD_KEY_SIZE ); +} + +static int CrackDiscKey( uint8_t *p_disc_key ) +{ + unsigned char B[5] = { 0,0,0,0,0 }; /* Second Stage of mangle cipher */ + unsigned char C[5] = { 0,0,0,0,0 }; /* Output Stage of mangle cipher + * IntermediateKey */ + unsigned char k[5] = { 0,0,0,0,0 }; /* Mangling cipher key + * Also output from CSS( C ) */ + unsigned char out1[5]; /* five first output bytes of LFSR1 */ + unsigned char out2[5]; /* five first output bytes of LFSR2 */ + unsigned int lfsr1a; /* upper 9 bits of LFSR1 */ + unsigned int lfsr1b; /* lower 8 bits of LFSR1 */ + unsigned int tmp, tmp2, tmp3, tmp4,tmp5; + int i, j, ret = 0; + unsigned int nStepA; /* iterator for LFSR1 start state */ + unsigned int nStepB; /* iterator for possible B[0] */ + unsigned int nTry; /* iterator for K[1] possibilities */ + unsigned int nPossibleK1; /* #of possible K[1] values */ + unsigned char* K1table; /* Lookup table for possible K[1] */ + unsigned int* BigTable; /* LFSR2 startstate indexed by + * 1,2,5 output byte */ + + /* + * Prepare tables for hash reversal + */ + + /* initialize lookup tables for k[1] */ + K1table = calloc( K1TABLESIZE, K1TABLEWIDTH ); + if( K1table == NULL ) + { + return -1; + } + + tmp = p_disc_key[0] ^ p_css_tab1[ p_disc_key[1] ]; + for( i = 0 ; i < 256 ; i++ ) /* k[1] */ + { + tmp2 = p_css_tab1[ tmp ^ i ]; /* p_css_tab1[ B[1] ]*/ + + for( j = 0 ; j < 256 ; j++ ) /* B[0] */ + { + tmp3 = j ^ tmp2 ^ i; /* C[1] */ + tmp4 = K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) ]; /* count of entries here */ + tmp4++; + if( tmp4 < K1TABLEWIDTH ) + { + K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) + tmp4 ] = i; + } + K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) ] = tmp4; + } + } + + /* Initializing our really big table */ + BigTable = calloc( BIGTABLESIZE, sizeof(*BigTable) ); + if( BigTable == NULL ) + { + free( K1table ); + return -1; + } + + tmp3 = 0; + + for( i = 0 ; i < BIGTABLESIZE ; i++ ) + { + tmp = (( i + i ) & 0x1fffff0 ) | 0x8 | ( i & 0x7 ); + + for( j = 0 ; j < 5 ; j++ ) + { + tmp2=((((((( tmp >> 3 ) ^ tmp ) >> 1 ) ^ tmp ) >> 8 ) + ^ tmp ) >> 5 ) & 0xff; + tmp = ( tmp << 8) | tmp2; + out2[j] = p_css_tab4[ tmp2 ]; + } + + j = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4]; + if ( j >= BIGTABLESIZE ) + { + ret = -1; + goto error; + } + BigTable[j] = i; + } + + /* + * We are done initializing, now reverse hash + */ + tmp5 = p_disc_key[0] ^ p_css_tab1[ p_disc_key[1] ]; + + for( nStepA = 0 ; nStepA < K1TABLESIZE ; nStepA ++ ) + { + lfsr1a = 0x100 | ( nStepA >> 8 ); + lfsr1b = nStepA & 0xff; + + /* Generate 5 first output bytes from lfsr1 */ + for( i = 0 ; i < 5 ; i++ ) + { + tmp = p_css_tab2[ lfsr1b ] ^ p_css_tab3[ lfsr1a ]; + lfsr1b = lfsr1a >> 1; + lfsr1a = ((lfsr1a&1)<<8) ^ tmp; + out1[ i ] = p_css_tab4[ tmp ]; + } + + /* compute and cache some variables */ + C[0] = nStepA >> 8; + C[1] = nStepA & 0xff; + tmp = p_disc_key[3] ^ p_css_tab1[ p_disc_key[4] ]; + tmp2 = p_css_tab1[ p_disc_key[0] ]; + + /* Search through all possible B[0] */ + for( nStepB = 0 ; nStepB < 256 ; nStepB++ ) + { + /* reverse parts of the mangling cipher */ + B[0] = nStepB; + k[0] = p_css_tab1[ B[0] ] ^ C[0]; + B[4] = B[0] ^ k[0] ^ tmp2; + k[4] = B[4] ^ tmp; + nPossibleK1 = K1table[ K1TABLEWIDTH * (256 * B[0] + C[1]) ]; + + /* Try out all possible values for k[1] */ + for( nTry = 0 ; nTry < nPossibleK1 ; nTry++ ) + { + k[1] = K1table[ K1TABLEWIDTH * (256 * B[0] + C[1]) + nTry + 1 ]; + B[1] = tmp5 ^ k[1]; + + /* reconstruct output from LFSR2 */ + tmp3 = ( 0x100 + k[0] - out1[0] ); + out2[0] = tmp3 & 0xff; + tmp3 = tmp3 & 0x100 ? 0x100 : 0xff; + tmp3 = ( tmp3 + k[1] - out1[1] ); + out2[1] = tmp3 & 0xff; + tmp3 = ( 0x100 + k[4] - out1[4] ); + out2[4] = tmp3 & 0xff; /* Can be 1 off */ + + /* test first possible out2[4] */ + tmp4 = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4]; + if ( tmp4 >= BIGTABLESIZE ) + { + ret = -1; + goto error; + } + tmp4 = BigTable[ tmp4 ]; + C[2] = tmp4 & 0xff; + C[3] = ( tmp4 >> 8 ) & 0xff; + C[4] = ( tmp4 >> 16 ) & 0xff; + B[3] = p_css_tab1[ B[4] ] ^ k[4] ^ C[4]; + k[3] = p_disc_key[2] ^ p_css_tab1[ p_disc_key[3] ] ^ B[3]; + B[2] = p_css_tab1[ B[3] ] ^ k[3] ^ C[3]; + k[2] = p_disc_key[1] ^ p_css_tab1[ p_disc_key[2] ] ^ B[2]; + + if( ( B[1] ^ p_css_tab1[ B[2] ] ^ k[ 2 ] ) == C[ 2 ] ) + { + if( ! investigate( &p_disc_key[0] , &C[0] ) ) + { + goto end; + } + } + + /* Test second possible out2[4] */ + out2[4] = ( out2[4] + 0xff ) & 0xff; + tmp4 = ( out2[0] << 16 ) | ( out2[1] << 8 ) | out2[4]; + if ( tmp4 >= BIGTABLESIZE ) + { + ret = -1; + goto error; + } + tmp4 = BigTable[ tmp4 ]; + C[2] = tmp4 & 0xff; + C[3] = ( tmp4 >> 8 ) & 0xff; + C[4] = ( tmp4 >> 16 ) & 0xff; + B[3] = p_css_tab1[ B[4] ] ^ k[4] ^ C[4]; + k[3] = p_disc_key[2] ^ p_css_tab1[ p_disc_key[3] ] ^ B[3]; + B[2] = p_css_tab1[ B[3] ] ^ k[3] ^ C[3]; + k[2] = p_disc_key[1] ^ p_css_tab1[ p_disc_key[2] ] ^ B[2]; + + if( ( B[1] ^ p_css_tab1[ B[2] ] ^ k[ 2 ] ) == C[ 2 ] ) + { + if( ! investigate( &p_disc_key[0] , &C[0] ) ) + { + goto end; + } + } + } + } + } + +end: + memcpy( p_disc_key, &C[0], DVD_KEY_SIZE ); + +error: + free( K1table ); + free( BigTable ); + + return ret; +} + +/***************************************************************************** + * RecoverTitleKey: (title) key recovery from cipher and plain text + * Function designed by Frank Stevenson + ***************************************************************************** + * Called from Attack* which are in turn called by CrackTitleKey. Given + * a guessed(?) plain text and the cipher text. Returns -1 on failure. + *****************************************************************************/ +static int RecoverTitleKey( int i_start, const uint8_t *p_crypted, + const uint8_t *p_decrypted, + const uint8_t *p_sector_seed, uint8_t *p_key ) +{ + uint8_t p_buffer[10]; + unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6; + unsigned int i_try; + unsigned int i_candidate; + unsigned int i, j; + int i_exit = -1; + + for( i = 0 ; i < 10 ; i++ ) + { + p_buffer[i] = p_css_tab1[p_crypted[i]] ^ p_decrypted[i]; + } + + for( i_try = i_start ; i_try < 0x10000 ; i_try++ ) + { + i_t1 = i_try >> 8 | 0x100; + i_t2 = i_try & 0xff; + i_t3 = 0; /* not needed */ + i_t5 = 0; + + /* iterate cipher 4 times to reconstruct LFSR2 */ + for( i = 0 ; i < 4 ; i++ ) + { + /* advance LFSR1 normally */ + i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1]; + i_t2 = i_t1 >> 1; + i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4; + i_t4 = p_css_tab5[i_t4]; + /* deduce i_t6 & i_t5 */ + i_t6 = p_buffer[i]; + if( i_t5 ) + { + i_t6 = ( i_t6 + 0xff ) & 0x0ff; + } + if( i_t6 < i_t4 ) + { + i_t6 += 0x100; + } + i_t6 -= i_t4; + i_t5 += i_t6 + i_t4; + i_t6 = p_css_tab4[ i_t6 ]; + /* feed / advance i_t3 / i_t5 */ + i_t3 = ( i_t3 << 8 ) | i_t6; + i_t5 >>= 8; + } + + i_candidate = i_t3; + + /* iterate 6 more times to validate candidate key */ + for( ; i < 10 ; i++ ) + { + i_t4 = p_css_tab2[i_t2] ^ p_css_tab3[i_t1]; + i_t2 = i_t1 >> 1; + i_t1 = ( ( i_t1 & 1 ) << 8 ) ^ i_t4; + i_t4 = p_css_tab5[i_t4]; + i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^ + i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff; + i_t3 = ( i_t3 << 8 ) | i_t6; + i_t6 = p_css_tab4[i_t6]; + i_t5 += i_t6 + i_t4; + if( ( i_t5 & 0xff ) != p_buffer[i] ) + { + break; + } + + i_t5 >>= 8; + } + + if( i == 10 ) + { + /* Do 4 backwards steps of iterating t3 to deduce initial state */ + i_t3 = i_candidate; + for( i = 0 ; i < 4 ; i++ ) + { + i_t1 = i_t3 & 0xff; + i_t3 = ( i_t3 >> 8 ); + /* easy to code, and fast enough brute-force + * search for byte shifted in */ + for( j = 0 ; j < 256 ; j++ ) + { + i_t3 = ( i_t3 & 0x1ffff ) | ( j << 17 ); + i_t6 = ((((((( i_t3 >> 3 ) ^ i_t3 ) >> 1 ) ^ + i_t3 ) >> 8 ) ^ i_t3 ) >> 5 ) & 0xff; + if( i_t6 == i_t1 ) + { + break; + } + } + } + + i_t4 = ( i_t3 >> 1 ) - 4; + for( i_t5 = 0 ; i_t5 < 8; i_t5++ ) + { + if( ( ( i_t4 + i_t5 ) * 2 + 8 - ( (i_t4 + i_t5 ) & 7 ) ) + == i_t3 ) + { + p_key[0] = i_try>>8; + p_key[1] = i_try & 0xFF; + p_key[2] = ( ( i_t4 + i_t5 ) >> 0 ) & 0xFF; + p_key[3] = ( ( i_t4 + i_t5 ) >> 8 ) & 0xFF; + p_key[4] = ( ( i_t4 + i_t5 ) >> 16 ) & 0xFF; + i_exit = i_try + 1; + } + } + } + } + + if( i_exit >= 0 ) + { + p_key[0] ^= p_sector_seed[0]; + p_key[1] ^= p_sector_seed[1]; + p_key[2] ^= p_sector_seed[2]; + p_key[3] ^= p_sector_seed[3]; + p_key[4] ^= p_sector_seed[4]; + } + + return i_exit; +} + + +/****************************************************************************** + * Various pieces for the title crack engine. + ****************************************************************************** + * The length of the PES packet is located at 0x12-0x13. + * The the copyright protection bits are located at 0x14 (bits 0x20 and 0x10). + * The data of the PES packet begins at 0x15 (if there isn't any PTS/DTS) + * or at 0x?? if there are both PTS and DTS's. + * The seed value used with the unscrambling key is the 5 bytes at 0x54-0x58. + * The scrambled part of a sector begins at 0x80. + *****************************************************************************/ + +/* Statistics */ +static int i_tries = 0, i_success = 0; + +/***************************************************************************** + * CrackTitleKey: try to crack title key from the contents of a VOB. + ***************************************************************************** + * This function is called by dvdcss_titlekey to find a title key, if we've + * chosen to crack title key instead of decrypting it with the disc key. + * The DVD should have been opened and be in an authenticated state. + * i_pos is the starting sector, i_len is the maximum number of sectors to read + *****************************************************************************/ +static int CrackTitleKey( dvdcss_t dvdcss, int i_pos, int i_len, + dvd_key p_titlekey ) +{ + uint8_t p_buf[ DVDCSS_BLOCK_SIZE ]; + const uint8_t p_packstart[4] = { 0x00, 0x00, 0x01, 0xba }; + int i_reads = 0; + int i_encrypted = 0; + int b_stop_scanning = 0; + int b_read_error = 0; + int i_ret; + + print_debug( dvdcss, "cracking title key at block %i", i_pos ); + + i_tries = 0; + i_success = 0; + + do + { + i_ret = dvdcss->pf_seek( dvdcss, i_pos ); + + if( i_ret != i_pos ) + { + print_error( dvdcss, "seek failed" ); + } + + i_ret = dvdcss_read( dvdcss, p_buf, 1, DVDCSS_NOFLAGS ); + + /* Either we are at the end of the physical device or the auth + * have failed / were not done and we got a read error. */ + if( i_ret <= 0 ) + { + if( i_ret == 0 ) + { + print_debug( dvdcss, "read returned 0 (end of device?)" ); + } + else if( !b_read_error ) + { + print_debug( dvdcss, "read error at block %i, resorting to " + "arcane secrets to recover", i_pos ); + + /* Reset the drive before trying to continue */ + dvdcss_close_device( dvdcss ); + dvdcss_open_device( dvdcss ); + + b_read_error = 1; + continue; + } + break; + } + + /* Stop when we find a non-MPEG stream block. + * (We must have reached the end of the stream). + * For now, allow all blocks that begin with a start code. */ + if( memcmp( p_buf, p_packstart, 3 ) ) + { + print_debug( dvdcss, "block %i is a non-MPEG block " + "(end of title)", i_pos ); + break; + } + + if( p_buf[0x0d] & 0x07 ) + print_debug( dvdcss, "stuffing in pack header" ); + + /* PES_scrambling_control does not exist in a system_header, + * a padding_stream or a private_stream2 (and others?). */ + if( p_buf[0x14] & 0x30 && ! ( p_buf[0x11] == 0xbb + || p_buf[0x11] == 0xbe + || p_buf[0x11] == 0xbf ) ) + { + i_encrypted++; + + if( AttackPattern( p_buf, p_titlekey ) > 0 ) + { + b_stop_scanning = 1; + } +#if 0 + if( AttackPadding( p_buf ) > 0 ) + { + b_stop_scanning = 1; + } +#endif /* 0 */ + } + + i_pos++; + i_len--; + i_reads++; + + /* Emit a progress indication now and then. */ + if( !( i_reads & 0xfff ) ) + { + print_debug( dvdcss, "at block %i, still cracking...", i_pos ); + } + + /* Stop after 2000 blocks if we haven't seen any encrypted blocks. */ + if( i_reads >= 2000 && i_encrypted == 0 ) break; + + } while( !b_stop_scanning && i_len > 0); + + if( !b_stop_scanning ) + { + print_debug( dvdcss, "end of title reached" ); + } + + /* Print some statistics. */ + print_debug( dvdcss, "successful attempts %d/%d, scrambled blocks %d/%d", + i_success, i_tries, i_encrypted, i_reads ); + + if( i_success > 0 /* b_stop_scanning */ ) + { + print_debug( dvdcss, "Video Title Set (VTS) key initialized" ); + return 1; + } + + if( i_encrypted == 0 && i_reads > 0 ) + { + memset( p_titlekey, 0, DVD_KEY_SIZE ); + print_debug( dvdcss, "no scrambled sectors found" ); + return 0; + } + + memset( p_titlekey, 0, DVD_KEY_SIZE ); + return -1; +} + + +/****************************************************************************** + * The original Ethan Hawke (DeCSSPlus) attack (modified). + ****************************************************************************** + * Tries to find a repeating pattern just before the encrypted part starts. + * Then it guesses that the plain text for first encrypted bytes are + * a continuation of that pattern. + *****************************************************************************/ +static int AttackPattern( const uint8_t p_sec[ DVDCSS_BLOCK_SIZE ], + uint8_t *p_key ) +{ + unsigned int i_best_plen = 0; + unsigned int i_best_p = 0; + unsigned int i, j; + + /* For all cycle length from 2 to 48 */ + for( i = 2 ; i < 0x30 ; i++ ) + { + /* Find the number of bytes that repeats in cycles. */ + for( j = i + 1; + j < 0x80 && ( p_sec[0x7F - (j%i)] == p_sec[0x7F - j] ); + j++ ) + { + /* We have found j repeating bytes with a cycle length i. */ + if( j > i_best_plen ) + { + i_best_plen = j; + i_best_p = i; + } + } + } + + /* We need at most 10 plain text bytes?, so a make sure that we + * have at least 20 repeated bytes and that they have cycled at + * least one time. */ + if( ( i_best_plen > 3 ) && ( i_best_plen / i_best_p >= 2) ) + { + int res; + + i_tries++; + memset( p_key, 0, DVD_KEY_SIZE ); + res = RecoverTitleKey( 0, &p_sec[0x80], + &p_sec[ 0x80 - (i_best_plen / i_best_p) * i_best_p ], + &p_sec[0x54] /* key_seed */, p_key ); + i_success += ( res >= 0 ); + return ( res >= 0 ); + } + + return 0; +} + + +#if 0 +/****************************************************************************** + * Encrypted Padding_stream attack. + ****************************************************************************** + * DVD specifies that there must only be one type of data in every sector. + * Every sector is one pack and so must obviously be 2048 bytes long. + * For the last piece of video data before a VOBU boundary there might not + * be exactly the right amount of data to fill a sector. Then one has to + * pad the pack to 2048 bytes. For just a few bytes this is done in the + * header but for any large amount you insert a PES packet from the + * Padding stream. This looks like 0x00 00 01 be xx xx ff ff ... + * where xx xx is the length of the padding stream. + *****************************************************************************/ +static int AttackPadding( const uint8_t p_sec[ DVDCSS_BLOCK_SIZE ] ) +{ + unsigned int i_pes_length; + /*static int i_tries = 0, i_success = 0;*/ + + i_pes_length = (p_sec[0x12]<<8) | p_sec[0x13]; + + /* Covered by the test below but useful for debugging. */ + if( i_pes_length == DVDCSS_BLOCK_SIZE - 0x14 ) return 0; + + /* There must be room for at least 4? bytes of padding stream, + * and it must be encrypted. + * sector size - pack/pes header - padding startcode - padding length */ + if( ( DVDCSS_BLOCK_SIZE - 0x14 - 4 - 2 - i_pes_length < 4 ) || + ( p_sec[0x14 + i_pes_length + 0] == 0x00 && + p_sec[0x14 + i_pes_length + 1] == 0x00 && + p_sec[0x14 + i_pes_length + 2] == 0x01 ) ) + { + fprintf( stderr, "plain %d %02x:%02x:%02x:%02x (type %02x sub %02x)\n", + DVDCSS_BLOCK_SIZE - 0x14 - 4 - 2 - i_pes_length, + p_sec[0x14 + i_pes_length + 0], + p_sec[0x14 + i_pes_length + 1], + p_sec[0x14 + i_pes_length + 2], + p_sec[0x14 + i_pes_length + 3], + p_sec[0x11], p_sec[0x17 + p_sec[0x16]]); + return 0; + } + + /* If we are here we know that there is a where in the pack a + encrypted PES header is (startcode + length). It's never more + than two packets in the pack, so we 'know' the length. The + plaintext at offset (0x14 + i_pes_length) will then be + 00 00 01 e0/bd/be xx xx, in the case of be the following bytes + are also known. */ + + /* An encrypted SPU PES packet with another encrypted PES packet following. + Normally if the following was a padding stream that would be in plain + text. So it will be another SPU PES packet. */ + if( p_sec[0x11] == 0xbd && + p_sec[0x17 + p_sec[0x16]] >= 0x20 && + p_sec[0x17 + p_sec[0x16]] <= 0x3f ) + { + i_tries++; + } + + /* A Video PES packet with another encrypted PES packet following. + * No reason except for time stamps to break the data into two packets. + * So it's likely that the following PES packet is a padding stream. */ + if( p_sec[0x11] == 0xe0 ) + { + i_tries++; + } + + return 0; +} +#endif /* 0 */ |