ref: 0a1535afb01a0b39b678575c509c91695bff0f06
dir: /src/css.c/
/*****************************************************************************
* css.c: Functions for DVD authentification and unscrambling
*****************************************************************************
* Copyright (C) 1999-2001 VideoLAN
* $Id: css.c,v 1.3 2002/02/25 18:21:57 hjort Exp $
*
* Author: St�phane Borel <stef@via.ecp.fr>
* H�kan 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>
* - 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 "dvdcss.h"
#include "common.h"
#include "css.h"
#include "libdvdcss.h"
#include "csstables.h"
#include "ioctl.h"
#ifdef HAVE_CSSKEYS
# include "csskeys.h"
#endif
/*****************************************************************************
* Local prototypes
*****************************************************************************/
static int CSSAuth ( dvdcss_handle dvdcss );
static int CSSGetASF ( dvdcss_handle dvdcss );
static void CSSCryptKey ( int i_key_type, int i_varient,
u8 const *p_challenge, u8 *p_key );
static void CSSDecryptKey( u8 *p_crypted, u8 const *p_key, u8 );
static int CSSDiscCrack ( dvdcss_handle dvdcss, u8 *p_disc_key );
static int CSSTitleCrack( int i_start, unsigned char *p_crypted,
unsigned char *p_decrypted,
u8 *p_sector_key, u8 *p_key );
/*****************************************************************************
* CSSTest : check if the disc is encrypted or not
*****************************************************************************/
int CSSTest( dvdcss_handle dvdcss )
{
int i_ret, i_copyright;
i_ret = ioctl_ReadCopyright( dvdcss->i_fd, 0 /* i_layer */, &i_copyright );
if( i_ret < 0 )
{
/* Since it's the first ioctl we try to issue, we add a notice */
_dvdcss_error( dvdcss, "css error: ioctl_ReadCopyright failed, "
"make sure there is a DVD in the drive, and that "
"DVD ioctls were compiled in this libdvdcss version" );
return i_ret;
}
return i_copyright;
}
/*****************************************************************************
* CSSAuth : DVD CSS authentication.
*****************************************************************************
* 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 CSSAuth( dvdcss_handle dvdcss )
{
u8 p_buffer[10];
u8 p_challenge[2*KEY_SIZE];
dvd_key_t p_key1;
dvd_key_t p_key2;
dvd_key_t p_key_check;
u8 i_varient = 0;
char psz_warning[48];
int i_ret = -1;
int i;
_dvdcss_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 )
{
_dvdcss_debug( dvdcss, "ioctl_ReportAgid failed" );
sprintf( psz_warning, "invalidating AGID %d", i );
_dvdcss_debug( dvdcss, psz_warning );
/* This is really _not good_, should be handled by the OS.
Invalidating an AGID could make another process fail some
where in it's authentication process. */
dvdcss->css.i_agid = i;
ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
_dvdcss_debug( dvdcss, "requesting AGID" );
i_ret = ioctl_ReportAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
}
/* Unable to authenticate without AGID */
if( i_ret == -1 )
{
_dvdcss_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 )
{
_dvdcss_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)
{
_dvdcss_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 )
{
CSSCryptKey( 0, i, p_challenge, p_key_check );
if( memcmp( p_key_check, p_key1, KEY_SIZE ) == 0 )
{
snprintf( psz_warning, sizeof(psz_warning),
"drive authentic, using varient %d", i );
_dvdcss_debug( dvdcss, psz_warning );
i_varient = i;
break;
}
}
if( i == 32 )
{
_dvdcss_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 )
{
_dvdcss_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];
}
CSSCryptKey( 1, i_varient, 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 )
{
_dvdcss_error( dvdcss, "ioctl_SendKey2 failed" );
ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
return -1;
}
/* The drive has accepted us as authentic. */
_dvdcss_debug( dvdcss, "authentication established" );
memcpy( p_challenge, p_key1, KEY_SIZE );
memcpy( p_challenge + KEY_SIZE, p_key2, KEY_SIZE );
CSSCryptKey( 2, i_varient, p_challenge, dvdcss->css.p_bus_key );
return 0;
}
/*****************************************************************************
* CSSPrintKey : debug function that dumps a key value
*****************************************************************************/static void CSSPrintKey( dvdcss_handle dvdcss, u8 *data )
{
char psz_output[80];
sprintf( psz_output, "the key is %02x %02x %02x %02x %02x",
data[0], data[1], data[2], data[3], data[4] );
_dvdcss_debug( dvdcss, psz_output );
}
/*****************************************************************************
* CSSGetDiscKey : get disc key and optionnaly decrypts it.
*****************************************************************************
* This function should only be called if DVD ioctls are present.
* Two decryption methods are then offered:
* -disc key hash crack,
* -decryption with player keys if they are available.
*****************************************************************************/
int CSSGetDiscKey( dvdcss_handle dvdcss )
{
unsigned char p_buffer[2048];
#ifdef HAVE_CSSKEYS
dvd_key_t disc_key;
dvd_key_t test_key;
#endif
int i;
if( CSSAuth( dvdcss ) )
{
return -1;
}
/* Get encrypted disc key */
if( ioctl_ReadDiscKey( dvdcss->i_fd, &dvdcss->css.i_agid, p_buffer ) < 0 )
{
_dvdcss_error( dvdcss, "ioctl_ReadDiscKey failed" );
return -1;
}
/* Unencrypt disc key using bus key */
for( i = 0 ; i < 2048 ; i++ )
{
p_buffer[ i ] ^= dvdcss->css.p_bus_key[ 4 - (i % KEY_SIZE) ];
}
switch( dvdcss->i_method )
{
case DVDCSS_METHOD_KEY:
#ifdef HAVE_CSSKEYS
/* Decrypt disc key with player keys from csskeys.h */
_dvdcss_debug( dvdcss, "decrypting disc key with player keys" );
i = 0;
do
{
/* Take encrypted disc key and decrypt it */
memcpy( disc_key,
p_buffer + playerkeys[i].i_offset,
KEY_SIZE );
CSSDecryptKey( disc_key, playerkeys[i].p_key, 0 );
/* Encrypt disc key hash with disc key to
* check we have disc key */
memcpy( test_key, p_buffer, KEY_SIZE );
CSSDecryptKey( test_key, disc_key, 0);
i++;
} while( ( playerkeys[i].i_offset != -1 ) &&
( memcmp( test_key, disc_key, KEY_SIZE ) ) );
/* Store decypted disk for use when decrypting title keys */
memcpy( dvdcss->css.p_disc_key, disc_key, KEY_SIZE );
break;
#else
dvdcss->i_method = DVDCSS_METHOD_DISC;
#endif
case DVDCSS_METHOD_DISC:
/* Crack Disc key to be able to use it */
_dvdcss_debug( dvdcss, "cracking disc key with key hash" );
_dvdcss_debug( dvdcss, "building 64MB table ... this will take some time" );
CSSDiscCrack( dvdcss, p_buffer );
memcpy( dvdcss->css.p_disc_key, p_buffer, KEY_SIZE );
break;
default:
_dvdcss_debug( dvdcss, "disc key won't be decrypted" );
}
CSSPrintKey( dvdcss, dvdcss->css.p_disc_key );
return 0;
}
/*****************************************************************************
* CSSGetTitleKey : get title key.
*****************************************************************************/
int CSSGetTitleKey( dvdcss_handle dvdcss, int i_pos )
{
dvd_key_t p_key;
int i,j;
if( ( dvdcss->i_method == DVDCSS_METHOD_TITLE )
|| ( dvdcss->b_ioctls == 0 ) )
{
/*
* Title key cracking method from Ethan Hawke,
* with Frank A. Stevenson algorithm.
* Does not use any player key table and ioctls.
*/
u8 p_buf[0x800];
u8 p_packstart[4] = { 0x00, 0x00, 0x01, 0xba };
boolean_t b_encrypted;
boolean_t b_stop_scanning;
int i_blocks_read;
int i_best_plen;
int i_best_p;
_dvdcss_debug( dvdcss, "cracking title key ... this may take some time" );
for( i = 0 ; i < KEY_SIZE ; i++ )
{
p_key[i] = 0;
}
b_encrypted = 0;
b_stop_scanning = 0;
i_blocks_read = 0;
do
{
i_pos = _dvdcss_seek( dvdcss, i_pos );
if( _dvdcss_read( dvdcss, p_buf, 1 ) != 1 ) break;
/* Stop when we find a non MPEG stream block */
if( memcmp( p_buf, p_packstart, 4 ) )
{
/* The title is unencrypted */
if( !b_encrypted )
break;
/* dvdcss some times fail to find/crack the key,
hope that it's the same as the one in the next title
_dvdcss_debug( dvdcss, "no key found at end of title" );
*/
}
/* PES_scrambling_control on and make sure that the packet type
is one that can be scrambled */
if( p_buf[0x14] & 0x30 && ! ( p_buf[0x11] == 0xbb
|| p_buf[0x11] == 0xbe
|| p_buf[0x11] == 0xbf ) )
{
b_encrypted = 1;
i_best_plen = 0;
i_best_p = 0;
for( i = 2 ; i < 0x30 ; i++ )
{
for( j = i+1 ;
j < 0x80 && ( p_buf[0x7F - (j%i)] == p_buf[0x7F-j] );
j++ );
{
if( j > i_best_plen )
{
i_best_plen = j;
i_best_p = i;
}
}
}
if( ( i_best_plen > 20 ) && ( i_best_plen / i_best_p >= 2) )
{
i = CSSTitleCrack( 0, &p_buf[0x80],
&p_buf[0x80 - ( i_best_plen / i_best_p) *i_best_p],
&p_buf[0x54],
p_key );
b_stop_scanning = ( i >= 0 );
}
}
i_pos += 1;
i_blocks_read += 1;
/* If we haven't seen any encrypted ones after 3000 blocks stop */
if( !b_encrypted && i_blocks_read >= 1000 ) break;
} while( !b_stop_scanning );
if( b_stop_scanning )
{
memcpy( dvdcss->css.p_title_key, &p_key, sizeof(dvd_key_t) );
CSSPrintKey( dvdcss, dvdcss->css.p_title_key );
_dvdcss_debug( dvdcss, "vts key initialized" );
return 0;
}
if( !b_encrypted )
{
_dvdcss_debug( dvdcss, "file was unscrambled" );
return 0;
}
return -1;
}
else
{
/*
* if we are here we have a decrypted disc key and ioctls are available
* so we can read the title key and decrypt it.
*/
_dvdcss_debug( dvdcss, "decrypting title key with disc key" );
/* We need to authenticate again for every title key,
* a new bus key is used each time. */
CSSAuth( dvdcss );
/* Get encrypted title key */
if( ioctl_ReadTitleKey( dvdcss->i_fd, &dvdcss->css.i_agid,
i_pos, p_key ) < 0 )
{
_dvdcss_error( dvdcss, "ioctl_ReadTitleKey failed" );
return -1;
}
/* Unencrypt title key using 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 realy wasn't any key pressent
* 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] ) )
{
memset( dvdcss->css.p_title_key, 0, sizeof(dvd_key_t) );
CSSPrintKey( dvdcss, dvdcss->css.p_title_key );
return 0;
}
/* Title key decryption needs one inversion 0xff */
CSSDecryptKey( p_key, dvdcss->css.p_disc_key, 0xff );
memcpy( dvdcss->css.p_title_key, p_key, sizeof(dvd_key_t) );
CSSPrintKey( dvdcss, dvdcss->css.p_title_key );
return 0;
} // (dvdcss->i_method == DVDCSS_METHOD_TITLE) || (dvdcss->b_ioctls == 0)
}
/*****************************************************************************
* CSSDescrambleSector: does the actual descrambling of data
*****************************************************************************
* sec : sector to descramble
* key : title key for this sector
*****************************************************************************/
int CSSDescrambleSector( dvd_key_t p_key, u8 *p_sec )
{
unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6;
u8 * p_end = p_sec + 0x800;
/* PES_scrambling_control */
if( p_sec[0x14] & 0x30)
{
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 */
/*****************************************************************************
* CSSGetASF : Get Authentification success flag
*****************************************************************************
* Returns :
* -1 on ioctl error,
* 0 if the device needs to be authenticated,
* 1 either.
*****************************************************************************/
static int CSSGetASF( dvdcss_handle dvdcss )
{
int i_asf = 0;
if( ioctl_ReportASF( dvdcss->i_fd, NULL, &i_asf ) != 0 )
{
/* The ioctl process has failed */
_dvdcss_error( dvdcss, "GetASF fatal error" );
return -1;
}
if( i_asf )
{
_dvdcss_debug( dvdcss, "GetASF authenticated (ASF=1)" );
}
else
{
_dvdcss_debug( dvdcss, "GetASF not authenticated (ASF=0)" );
}
return i_asf;
}
/*****************************************************************************
* CSSCryptKey : shuffles bits and unencrypt keys.
*****************************************************************************
* Used during authentication and disc key negociation in CSSAuth.
* i_key_type : 0->key1, 1->key2, 2->buskey.
* i_varient : between 0 and 31.
*****************************************************************************/
static void CSSCryptKey( int i_key_type, int i_varient,
u8 const *p_challenge, u8 *p_key )
{
/* Permutation table for challenge */
u8 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 varient table for key2 and buskey */
u8 pp_perm_varient[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 } };
u8 p_varients[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 */
u8 p_secret[5] = { 0x55, 0xD6, 0xC4, 0xC5, 0x28 };
u8 p_bits[30];
u8 p_scratch[10];
u8 p_tmp1[5];
u8 p_tmp2[5];
u8 i_lfsr0_o; /* 1 bit used */
u8 i_lfsr1_o; /* 1 bit used */
u32 i_lfsr0;
u32 i_lfsr1;
u8 i_css_varient;
u8 i_cse;
u8 i_index;
u8 i_combined;
u8 i_carry;
u8 i_val = 0;
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_varient = ( i_key_type == 0 ) ? i_varient :
pp_perm_varient[i_key_type-1][i_varient];
/*
* This encryption engine implements one of 32 variations
* one the same theme depending upon the choice in the
* varient 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_varients[i_css_varient] ^ p_crypt_tab2[i_css_varient];
/* 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;
}
/*****************************************************************************
* CSSDecryptKey: decrypt p_crypted with p_key.
*****************************************************************************
* 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 CSSDecryptKey( u8 *p_crypted, u8 const *p_key, u8 invert )
{
unsigned int i_lfsr1_lo;
unsigned int i_lfsr1_hi;
unsigned int i_lfsr0;
unsigned int i_combined;
byte_t o_lfsr0;
byte_t o_lfsr1;
byte_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_crypted[4] = k[4] ^ p_css_tab1[p_crypted[4]] ^ p_crypted[3];
p_crypted[3] = k[3] ^ p_css_tab1[p_crypted[3]] ^ p_crypted[2];
p_crypted[2] = k[2] ^ p_css_tab1[p_crypted[2]] ^ p_crypted[1];
p_crypted[1] = k[1] ^ p_css_tab1[p_crypted[1]] ^ p_crypted[0];
p_crypted[0] = k[0] ^ p_css_tab1[p_crypted[0]] ^ p_crypted[4];
p_crypted[4] = k[4] ^ p_css_tab1[p_crypted[4]] ^ p_crypted[3];
p_crypted[3] = k[3] ^ p_css_tab1[p_crypted[3]] ^ p_crypted[2];
p_crypted[2] = k[2] ^ p_css_tab1[p_crypted[2]] ^ p_crypted[1];
p_crypted[1] = k[1] ^ p_css_tab1[p_crypted[1]] ^ p_crypted[0];
p_crypted[0] = k[0] ^ p_css_tab1[p_crypted[0]];
return;
}
/*****************************************************************************
* CSSDiscCrack: 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 K1TABLEWIDTH 10
/*
* Simple function to test if a candidate key produces the given hash
*/
static int investigate( unsigned char *hash, unsigned char *ckey )
{
unsigned char key[5];
unsigned char pkey[5];
memcpy( key, hash, 5 );
memcpy( pkey, ckey, 5 );
CSSDecryptKey( key, pkey, 0 );
return memcmp( key, pkey, 5 );
}
static int CSSDiscCrack( dvdcss_handle dvdcss, u8 *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;
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 = malloc( 65536 * K1TABLEWIDTH );
memset( K1table, 0 , 65536 * 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 )
{
_dvdcss_debug( dvdcss, "Table disaster %d", tmp4 );
}
*/
if( tmp4 < K1TABLEWIDTH )
{
K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) + tmp4 ] = i;
}
K1table[ K1TABLEWIDTH * ( 256 * j + tmp3 ) ] = tmp4;
}
}
/* Initing our Really big table */
BigTable = malloc( 16777216 * sizeof(int) );
memset( BigTable, 0 , 16777216 * sizeof(int) );
if( BigTable == NULL )
{
return -1;
}
tmp3 = 0;
_dvdcss_debug( dvdcss, "initializing the big table" );
for( i = 0 ; i < 16777216 ; i++ )
{
/*
if( ( i & 0x07ffff ) == 0 )
{
fprintf( stderr, "#" );
}
*/
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];
BigTable[j] = i;
}
/* fprintf( stderr, "\n" ); */
/*
* We are done initing, now reverse hash
*/
tmp5 = p_disc_key[0] ^ p_css_tab1[ p_disc_key[1] ];
for( nStepA = 0 ; nStepA < 65536 ; 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 ];
}
/* cumpute 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];
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];
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], KEY_SIZE );
free( K1table );
free( BigTable );
return( 0 );
}
/*****************************************************************************
* CSSTitleCrack : title key decryption by cracking
* Function designed by Frank Stevenson
*****************************************************************************
* This function is called by CSSGetTitleKey to find a title key, if we've
* chosen to crack title key instead of decrypting it with the disc key.
*****************************************************************************/
static int CSSTitleCrack( int i_start,
unsigned char *p_crypted,
unsigned char *p_decrypted,
u8 *p_sector_seed,
u8 *p_key )
{
unsigned char 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 normaly */
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 bruteforce
* 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;
}