css.c

来自「君正早期ucos系统(只有早期的才不没有打包成库),MPLAYER,文件系统,图」· C语言 代码 · 共 1,697 行 · 第 1/4 页

        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 },
    { 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, uint8_t const *p_struct_disckey,
                           dvd_key_t p_disc_key )
{
    uint8_t p_verify[KEY_SIZE];
    unsigned int i, n = 0;

    /* Decrypt disc key with the above player keys */
    for( n = 0; n < sizeof(player_keys) / sizeof(dvd_key_t); 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, KEY_SIZE ) == 0 )
            {
                return 0;
            }
        }
    }

    /* Have tried all combinations of positions and keys,
     * and we still didn't succeed. */
    memset( p_disc_key, 0, 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_t p_disc_key, dvd_key_t 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 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[KEY_SIZE];

    DecryptKey( 0, ckey, hash, key );

    return memcmp( key, ckey, KEY_SIZE );
}

static int CrackDiscKey( dvdcss_t dvdcss, 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;
    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 )
            {
                print_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;

    print_debug( dvdcss, "initializing the big table" );

    for( i = 0 ; i < 16777216 ; 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];
        BigTable[j] = i;
    }

    /*
     * 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 );