/*•••••*••css_descramble.c•••••*•••••*••Released•under•the•version•2•of•the•GPL.•••••*•••••*••Copyright•1999•Derek•Fawcus•••••*•••••*••This•file•contains•functions•to•descramble•CSS•encrypted•DVD•conten
t•••••*•••••*/••••••••/*•••••*••Still•in•progress:••Remove•the•use•of•the•bit_reverse[]•table•by•recoding•••••*••••••••••••••••••••••the•generation•of•LFSR1.••Finish•combining•this•with•••••*•••••••••••
•••••••••••the•css•authentication•code.•••••*•••••*/••••••••#include•(stdio.h)••••#include•(string.h)••••#include•"css-descramble.h"••••••••typedef•unsigned•char•byte;••••••••/*•••••*•••••*••some•tables
•used•for•descrambling•sectors•and/or•decrypting•title•keys•••••*•••••*/••••••••static•byte•csstab1[256]=••••{•••••0x33,0x73,0x3b,0x26,0x63,0x23,0x6b,0x76,0x3e,0x7e,0x36,0x2b,0x6e,0x2e,0x66,0x7b,•••••0x
d3,0x93,0xdb,0x06,0x43,0x03,0x4b,0x96,0xde,0x9e,0xd6,0x0b,0x4e,0x0e,0x46,0x9b,•••••0x57,0x17,0x5f,0x82,0xc7,0x87,0xcf,0x12,0x5a,0x1a,0x52,0x8f,0xca,0x8a,0xc2,0x1f,•••••0xd9,0x99,0xd1,0x00,0x49,0x09,0x41
,0x90,0xd8,0x98,0xd0,0x01,0x48,0x08,0x40,0x91,•••••0x3d,0x7d,0x35,0x24,0x6d,0x2d,0x65,0x74,0x3c,0x7c,0x34,0x25,0x6c,0x2c,0x64,0x75,•••••0xdd,0x9d,0xd5,0x04,0x4d,0x0d,0x45,0x94,0xdc,0x9c,0xd4,0x05,0x4c,0
x0c,0x44,0x95,•••••0x59,0x19,0x51,0x80,0xc9,0x89,0xc1,0x10,0x58,0x18,0x50,0x81,0xc8,0x88,0xc0,0x11,•••••0xd7,0x97,0xdf,0x02,0x47,0x07,0x4f,0x92,0xda,0x9a,0xd2,0x0f,0x4a,0x0a,0x42,0x9f,•••••0x53,0x13,0x5
b,0x86,0xc3,0x83,0xcb,0x16,0x5e,0x1e,0x56,0x8b,0xce,0x8e,0xc6,0x1b,•••••0xb3,0xf3,0xbb,0xa6,0xe3,0xa3,0xeb,0xf6,0xbe,0xfe,0xb6,0xab,0xee,0xae,0xe6,0xfb,•••••0x37,0x77,0x3f,0x22,0x67,0x27,0x6f,0x72,0x3a,
0x7a,0x32,0x2f,0x6a,0x2a,0x62,0x7f,•••••0xb9,0xf9,0xb1,0xa0,0xe9,0xa9,0xe1,0xf0,0xb8,0xf8,0xb0,0xa1,0xe8,0xa8,0xe0,0xf1,•••••0x5d,0x1d,0x55,0x84,0xcd,0x8d,0xc5,0x14,0x5c,0x1c,0x54,0x85,0xcc,0x8c,0xc4,0x
15,•••••0xbd,0xfd,0xb5,0xa4,0xed,0xad,0xe5,0xf4,0xbc,0xfc,0xb4,0xa5,0xec,0xac,0xe4,0xf5,•••••0x39,0x79,0x31,0x20,0x69,0x29,0x61,0x70,0x38,0x78,0x30,0x21,0x68,0x28,0x60,0x71,•••••0xb7,0xf7,0xbf,0xa2,0xe7
,0xa7,0xef,0xf2,0xba,0xfa,0xb2,0xaf,0xea,0xaa,0xe2,0xff••••};••••••••static•byte•lfsr1_bits0[256]=••••{•••••0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x09,0x08,0x0b,0x0a,0x0d,0x0c,0x0f,0x0e,•••••0x12,0x13
,0x10,0x11,0x16,0x17,0x14,0x15,0x1b,0x1a,0x19,0x18,0x1f,0x1e,0x1d,0x1c,•••••0x24,0x25,0x26,0x27,0x20,0x21,0x22,0x23,0x2d,0x2c,0x2f,0x2e,0x29,0x28,0x2b,0x2a,•••••0x36,0x37,0x34,0x35,0x32,0x33,0x30,0x31,0
x3f,0x3e,0x3d,0x3c,0x3b,0x3a,0x39,0x38,•••••0x49,0x48,0x4b,0x4a,0x4d,0x4c,0x4f,0x4e,0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47,•••••0x5b,0x5a,0x59,0x58,0x5f,0x5e,0x5d,0x5c,0x52,0x53,0x50,0x51,0x56,0x57,0x5
4,0x55,•••••0x6d,0x6c,0x6f,0x6e,0x69,0x68,0x6b,0x6a,0x64,0x65,0x66,0x67,0x60,0x61,0x62,0x63,•••••0x7f,0x7e,0x7d,0x7c,0x7b,0x7a,0x79,0x78,0x76,0x77,0x74,0x75,0x72,0x73,0x70,0x71,•••••0x92,0x93,0x90,0x91,
0x96,0x97,0x94,0x95,0x9b,0x9a,0x99,0x98,0x9f,0x9e,0x9d,0x9c,•••••0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87,0x89,0x88,0x8b,0x8a,0x8d,0x8c,0x8f,0x8e,•••••0xb6,0xb7,0xb4,0xb5,0xb2,0xb3,0xb0,0xb1,0xbf,0xbe,0x
bd,0xbc,0xbb,0xba,0xb9,0xb8,•••••0xa4,0xa5,0xa6,0xa7,0xa0,0xa1,0xa2,0xa3,0xad,0xac,0xaf,0xae,0xa9,0xa8,0xab,0xaa,•••••0xdb,0xda,0xd9,0xd8,0xdf,0xde,0xdd,0xdc,0xd2,0xd3,0xd0,0xd1,0xd6,0xd7,0xd4,0xd5,••••
•0xc9,0xc8,0xcb,0xca,0xcd,0xcc,0xcf,0xce,0xc0,0xc1,0xc2,0xc3,0xc4,0xc5,0xc6,0xc7,•••••0xff,0xfe,0xfd,0xfc,0xfb,0xfa,0xf9,0xf8,0xf6,0xf7,0xf4,0xf5,0xf2,0xf3,0xf0,0xf1,•••••0xed,0xec,0xef,0xee,0xe9,0xe8,0
xeb,0xea,0xe4,0xe5,0xe6,0xe7,0xe0,0xe1,0xe2,0xe3••••};••••••••static•byte•lfsr1_bits1[512]=••••{•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0
x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x2
4,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,
•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0x
b6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d
,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0
x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xf
f,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,
0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x
6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24
,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•
••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb
6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,
0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,•••••0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff,0x00,0x24,0x49,0x6d,0x92,0xb6,0xdb,0xff••••};•••••••
•/*•Reverse•the•order•of•the•bits•within•a•byte.•••••*/••••static•byte•bit_reverse[256]=••••{•••••0x00,0x80,0x40,0xc0,0x20,0xa0,0x60,0xe0,0x10,0x90,0x50,0xd0,0x30,0xb0,0x70,0xf0,•••••0x08,0x88,0x48,0xc8
,0x28,0xa8,0x68,0xe8,0x18,0x98,0x58,0xd8,0x38,0xb8,0x78,0xf8,•••••0x04,0x84,0x44,0xc4,0x24,0xa4,0x64,0xe4,0x14,0x94,0x54,0xd4,0x34,0xb4,0x74,0xf4,•••••0x0c,0x8c,0x4c,0xcc,0x2c,0xac,0x6c,0xec,0x1c,0x9c,0
x5c,0xdc,0x3c,0xbc,0x7c,0xfc,•••••0x02,0x82,0x42,0xc2,0x22,0xa2,0x62,0xe2,0x12,0x92,0x52,0xd2,0x32,0xb2,0x72,0xf2,•••••0x0a,0x8a,0x4a,0xca,0x2a,0xaa,0x6a,0xea,0x1a,0x9a,0x5a,0xda,0x3a,0xba,0x7a,0xfa,•••
••0x06,0x86,0x46,0xc6,0x26,0xa6,0x66,0xe6,0x16,0x96,0x56,0xd6,0x36,0xb6,0x76,0xf6,•••••0x0e,0x8e,0x4e,0xce,0x2e,0xae,0x6e,0xee,0x1e,0x9e,0x5e,0xde,0x3e,0xbe,0x7e,0xfe,•••••0x01,0x81,0x41,0xc1,0x21,0xa1,
0x61,0xe1,0x11,0x91,0x51,0xd1,0x31,0xb1,0x71,0xf1,•••••0x09,0x89,0x49,0xc9,0x29,0xa9,0x69,0xe9,0x19,0x99,0x59,0xd9,0x39,0xb9,0x79,0xf9,•••••0x05,0x85,0x45,0xc5,0x25,0xa5,0x65,0xe5,0x15,0x95,0x55,0xd5,0x
35,0xb5,0x75,0xf5,•••••0x0d,0x8d,0x4d,0xcd,0x2d,0xad,0x6d,0xed,0x1d,0x9d,0x5d,0xdd,0x3d,0xbd,0x7d,0xfd,•••••0x03,0x83,0x43,0xc3,0x23,0xa3,0x63,0xe3,0x13,0x93,0x53,0xd3,0x33,0xb3,0x73,0xf3,•••••0x0b,0x8b
,0x4b,0xcb,0x2b,0xab,0x6b,0xeb,0x1b,0x9b,0x5b,0xdb,0x3b,0xbb,0x7b,0xfb,•••••0x07,0x87,0x47,0xc7,0x27,0xa7,0x67,0xe7,0x17,0x97,0x57,0xd7,0x37,0xb7,0x77,0xf7,•••••0x0f,0x8f,0x4f,0xcf,0x2f,0xaf,0x6f,0xef,0
x1f,0x9f,0x5f,0xdf,0x3f,0xbf,0x7f,0xff••••};••••••••/*•••••*•••••*•this•function•is•only•used•internally•when•decrypting•title•key•••••*•••••*/••••static•void•css_titlekey(byte•*key,•byte•*im,•byte•inve
rt)••••{•••••unsigned•int•lfsr1_lo,lfsr1_hi,lfsr0,combined;•••••byte•o_lfsr0,•o_lfsr1;•••••byte•k[5];•••••int•i;•••••••••lfsr1_lo•=•im[0]•|•0x100;•••••lfsr1_hi•=•im[1];•••••••••lfsr0•=•((im[4]•((•17)•|•
(im[3]•((•9)•|•(im[2]•((•1))•+•8•-•(im[2]&7);•••••lfsr0•=•(bit_reverse[lfsr0&0xff]((24)•|•(bit_reverse[(lfsr0))8)&0xff]•((•16)••••••••|•(bit_reverse[(lfsr0))16)&0xff]((8)•|•bit_reverse[(lfsr0))24)&0xff]
;•••••••••combined•=•0;•••••for•(i•=•0;•i•(•5;•++i)•{••••••o_lfsr1••=•lfsr1_bits0[lfsr1_hi]•^•lfsr1_bits1[lfsr1_lo];••••••••lfsr1_hi•=•lfsr1_lo))1;••••••••lfsr1_lo•=•((lfsr1_lo&1)((8)•^•o_lfsr1;••••••o_
lfsr1••=•bit_reverse[o_lfsr1];••••••••••/*o_lfsr0•=•(lfsr0))7)^(lfsr0))10)^(lfsr0))11)^(lfsr0))19);*/••••••o_lfsr0•=•(((((((lfsr0))8)^lfsr0)))1)^lfsr0)))3)^lfsr0)))7);••••••••lfsr0•=•(lfsr0))8)|(o_lfsr0
((24);••••••••••combined•+=•(o_lfsr0•^•invert)•+•o_lfsr1;••••••k[i]•=•combined•&•0xff;••••••combined•))=•8;•••••}•••••••••key[4]=k[4]^csstab1[key[4]]^key[3];•••••key[3]=k[3]^csstab1[key[3]]^key[2];•••••
key[2]=k[2]^csstab1[key[2]]^key[1];•••••key[1]=k[1]^csstab1[key[1]]^key[0];•••••key[0]=k[0]^csstab1[key[0]]^key[4];•••••••••key[4]=k[4]^csstab1[key[4]]^key[3];•••••key[3]=k[3]^csstab1[key[3]]^key[2];•••
••key[2]=k[2]^csstab1[key[2]]^key[1];•••••key[1]=k[1]^csstab1[key[1]]^key[0];•••••key[0]=k[0]^csstab1[key[0]];••••}••••••••/*•••••*•••••*•this•function•decrypts•a•title•key•with•the•specified•disk•key••
•••*•••••*•tkey:•the•unobfuscated•title•key•(XORed•with•BusKey)•••••*•dkey:•the•unobfuscated•disk•key•(XORed•with•BusKey)•••••*•••••••2048•bytes•in•length•(though•only•5•bytes•are•needed,•see•below)••••
•*•pkey:•array•of•pointers•to•player•keys•and•disk•key•offsets•••••*•••••*•••••*•use•the•result•returned•in•tkey•with•css_descramble•••••*•••••*/••••••••int•css_decrypttitlekey(byte•*tkey,•byte•*dkey,•s
truct•playkey•**pkey)••••{•••••byte•test[5],•pretkey[5];•••••int•i•=•0;•••••••••for•(;•*pkey;•++pkey,•++i)•{••••••memcpy(pretkey,•dkey•+•(*pkey)-)offset,•5);••••••css_titlekey(pretkey,•(*pkey)-)key,•0);
••••••••••memcpy(test,•dkey,•5);••••••css_titlekey(test,•pretkey,•0);••••••••••if•(memcmp(test,•pretkey,•5)•==•0)•{•••••••fprintf(stderr,•"Using•Key•%d\n",•i+1);•••••••break;••••••}•••••}•••••••••if•(!*
pkey)•{••••••fprintf(stderr,•"Shit•-•Need•Key•%d\n",•i+1);••••••return•0;•••••}•••••••••css_titlekey(tkey,•pretkey,•0xff);•••••••••return•1;••••}••••••••/*•••••*•••••*•this•function•does•the•actual•desc
rambling•••••*•••••*•sec:•encrypted•sector•(2048•bytes)•••••*•key:•decrypted•title•key•obtained•from•css_decrypttitlekey•••••*•••••*/••••void•css_descramble(byte•*sec,byte•*key)••••{•••••unsigned•int•lf
sr1_lo,lfsr1_hi,lfsr0,combined;•••••unsigned•char•o_lfsr0,•o_lfsr1;•••••unsigned•char•*end•=•sec•+•0x800;••••#define•SALTED(i)•(key[i]•^•sec[0x54•+•(i)])•••••••••lfsr1_lo•=•SALTED(0)•|•0x100;•••••lfsr1_
hi•=•SALTED(1);•••••••••lfsr0•=•((SALTED(4)•((•17)•|•(SALTED(3)•((•9)•|•(SALTED(2)•((•1))•+•8•-•(SALTED(2)&7);•••••lfsr0•=•(bit_reverse[lfsr0&0xff]((24)•|•(bit_reverse[(lfsr0))8)&0xff]•((•16)••••••••|•(
bit_reverse[(lfsr0))16)&0xff]((8)•|•bit_reverse[(lfsr0))24)&0xff];•••••••••sec+=0x80;•••••combined•=•0;•••••while•(sec•!=•end)•{••••••o_lfsr1••=•lfsr1_bits0[lfsr1_hi]•^•lfsr1_bits1[lfsr1_lo];••••••••lfs
r1_hi•=•lfsr1_lo))1;••••••••lfsr1_lo•=•((lfsr1_lo&1)((8)•^•o_lfsr1;••••••o_lfsr1••=•bit_reverse[o_lfsr1];••••••••••/*o_lfsr0•=•(lfsr0))7)^(lfsr0))10)^(lfsr0))11)^(lfsr0))19);*/••••••o_lfsr0•=•(((((((lfs
r0))8)^lfsr0)))1)^lfsr0)))3)^lfsr0)))7);••••••••lfsr0•=•(lfsr0))8)|(o_lfsr0((24);••••••••••combined•+=•o_lfsr0•+•(byte)~o_lfsr1;••••••*sec++•=•csstab1[*sec]•^•(combined&0xff);••••••combined•))=•8;•••••}
••••}/*•###############################################################################################################################################################################################•*/