diff options
Diffstat (limited to 'libdvdcss/css.c')
-rw-r--r-- | libdvdcss/css.c | 1695 |
1 files changed, 1695 insertions, 0 deletions
diff --git a/libdvdcss/css.c b/libdvdcss/css.c new file mode 100644 index 0000000000..a704a3fcf9 --- /dev/null +++ b/libdvdcss/css.c @@ -0,0 +1,1695 @@ +/***************************************************************************** + * css.c: Functions for DVD authentication and descrambling + ***************************************************************************** + * Copyright (C) 1999-2003 VideoLAN + * $Id$ + * + * 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. + * + * This program 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. + * + * This program 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 this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. + *****************************************************************************/ + +/***************************************************************************** + * Preamble + *****************************************************************************/ +#include "config.h" + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/types.h> +#include <sys/stat.h> +#ifdef HAVE_SYS_PARAM_H +# include <sys/param.h> +#endif +#ifdef HAVE_UNISTD_H +# include <unistd.h> +#endif +#include <fcntl.h> + +#ifdef HAVE_LIMITS_H +# include <limits.h> +#endif + +#include "dvdcss/dvdcss.h" + +#include "common.h" +#include "css.h" +#include "libdvdcss.h" +#include "csstables.h" +#include "ioctl.h" +#include "device.h" + +/***************************************************************************** + * Local prototypes + *****************************************************************************/ +static void PrintKey ( dvdcss_t, char *, uint8_t const * ); + +static int GetBusKey ( dvdcss_t ); +static int GetASF ( dvdcss_t ); + +static void CryptKey ( int, int, uint8_t const *, uint8_t * ); +static void DecryptKey ( uint8_t, + uint8_t const *, uint8_t const *, uint8_t * ); + +static int DecryptDiscKey ( dvdcss_t, uint8_t const *, dvd_key_t ); +static int CrackDiscKey ( dvdcss_t, uint8_t * ); + +static void DecryptTitleKey ( dvd_key_t, dvd_key_t ); +static int RecoverTitleKey ( int, uint8_t const *, + uint8_t const *, uint8_t const *, uint8_t * ); +static int CrackTitleKey ( dvdcss_t, int, int, dvd_key_t ); + +static int AttackPattern ( uint8_t const[], int, uint8_t * ); +#if 0 +static int AttackPadding ( uint8_t const[], int, uint8_t * ); +#endif + +/***************************************************************************** + * _dvdcss_test: check if the disc is encrypted or not + *****************************************************************************/ +int _dvdcss_test( dvdcss_t dvdcss ) +{ + int i_ret, i_copyright; + + i_ret = ioctl_ReadCopyright( dvdcss->i_fd, 0 /* i_layer */, &i_copyright ); + +#ifdef WIN32 + if( i_ret < 0 ) + { + /* 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. */ + i_ret = 0; + i_copyright = 1; + if( _dvdcss_disckey( dvdcss ) < 0 ) + { + i_copyright = 0; + } + } +#endif + + if( i_ret < 0 ) + { + /* Since it's the first ioctl we try to issue, we add a notice */ + print_error( dvdcss, "css error: ioctl_ReadCopyright failed, " + "make sure there is a DVD in the drive, and that " + "you have used the correct device node." ); + + return i_ret; + } + + return i_copyright; +} + +/***************************************************************************** + * _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 ) +{ + dvd_title_t *p_title; + dvd_title_t *p_newtitle; + dvd_key_t 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(dvd_key_t) ); + 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, "%.10x", i_block ); + i_fd = open( dvdcss->psz_cachefile, O_RDONLY ); + b_cache = 1; + + if( i_fd >= 0 ) + { + char psz_key[KEY_SIZE * 3]; + unsigned int k0, k1, k2, k3, k4; + + psz_key[KEY_SIZE * 3 - 1] = '\0'; + + if( read( i_fd, psz_key, KEY_SIZE * 3 - 1 ) == KEY_SIZE * 3 - 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 CSS title key for current 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 vts 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[KEY_SIZE * 3 + 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] ); + + write( i_fd, psz_key, KEY_SIZE * 3 + 1 ); + 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( dvd_title_t ) ); + p_newtitle->i_startlb = i_block; + memcpy( p_newtitle->p_key, p_title_key, 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, 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_t 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 invaidated 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, + "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 % 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 */ + 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, KEY_SIZE ); + PrintKey( dvdcss, "cracking disc key ", p_disc_key ); + if( ! CrackDiscKey( dvdcss, 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, KEY_SIZE ); + dvdcss->i_method = DVDCSS_METHOD_TITLE; + break; + + default: + + print_debug( dvdcss, "disc key needs not be decrypted" ); + memset( p_disc_key, 0, KEY_SIZE ); + break; + } + + memcpy( dvdcss->css.p_disc_key, p_disc_key, KEY_SIZE ); + + return 0; +} + + +/***************************************************************************** + * _dvdcss_titlekey: get title key. + *****************************************************************************/ +int _dvdcss_titlekey( dvdcss_t dvdcss, int i_pos, dvd_key_t p_title_key ) +{ + static uint8_t p_garbage[ DVDCSS_BLOCK_SIZE ]; /* we never read it back */ + uint8_t p_key[ 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 ) + { + return -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 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 ASF requesting title key" ); + break; + + case 1: + /* Drive status is ok. */ + /* If the title key request failed, but we did not loose ASF, + * we might stil have the AGID. Other code assume 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 < KEY_SIZE ; i++ ) + { + p_key[ i ] ^= dvdcss->css.p_bus_key[ 4 - (i % 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, 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, 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_t 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 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 says + * 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*KEY_SIZE]; + dvd_key_t p_key1; + dvd_key_t p_key2; + dvd_key_t p_key_check; + uint8_t i_variant = 0; + int i_ret = -1; + int i; + + print_debug( dvdcss, "requesting 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 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 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 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 < 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, 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 < 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, KEY_SIZE ); + memcpy( p_challenge + KEY_SIZE, p_key2, 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, char *prefix, uint8_t const *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 + ***************************************************************************** + * 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, NULL, &i_asf ) != 0 ) + { + /* The ioctl process has failed */ + print_error( dvdcss, "GetASF fatal error" ); + return -1; + } + + if( i_asf ) + { + print_debug( dvdcss, "GetASF authenticated, ASF=1" ); + } + else + { + print_debug( dvdcss, "GetASF not authenticated, ASF=0" ); + } + + return i_asf; +} + +/***************************************************************************** + * CryptKey : shuffles bits and unencrypt keys. + ***************************************************************************** + * Used during authentication and disc key negociation 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, + uint8_t const *p_challenge, uint8_t *p_key ) +{ + /* Permutation table for challenge */ + 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 */ + 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 } }; + + 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 */ + 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 LSFR 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 initialise 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 dependant on the type of key: + * -for disc key, invert is 0x00, + * -for title key, invert if 0xff. + *****************************************************************************/ +static void DecryptKey( uint8_t invert, uint8_t const *p_key, + uint8_t const *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 < 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_t 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 |