NOTE: This story is licenced under the GPL version 2.

It is a dark and stormy night in a dark and stormy town. Tonight we find ourselves looking apon Dick and Jane, two programmers bundled up by the fire discussing current events:

"So, Jane, how was your day?" says Dick.

"Oh, fine. You know, I just heard about this interesting program that is creating quite a fuss." says Jane, "It is called 'css_descramble.c'.".

"Wow," Dick enthused, "I have heard of it. My buddy kept talking about it. He couldn't stop mentioning how it was...how did he put it? Ah yes, 'Released under the version 2 of the GPL and Copyright 1999 Derek Fawcus'".

Jane jumped with joy. "I am so glad you have heard of it. I happen to have a copy. Here, look. The very first thing it does is '#include ' then it has '#include '."

"You are right, but you forgot '#include "css-descramble.h"'" Dick admonished.

Jane blushed, "Silly me. Well, we should have a look at the code. It seems to start with 'typedef unsigned char byte;'. Then it moves right along to an array. What is that? Oh, 'static byte csstab1[256]={'"

"I know!" Dick blurted, "lets play a number game! I will say a bunch of numbers, then you can repeat the numbers. Ready? '0x33, 0x73, 0x3b, 0x26, 0x63, 0x23, 0x6b, 0x76, 0x3e, 0x7e, 0x36, 0x2b, 0x6e, 0x2e, 0x66, 0x7b,'"

"Hmmm...that is one long list of numbers...let me see. Was it, ' 0xd3, 0x93, 0xdb, 0x06, 0x43, 0x03, 0x4b, 0x96, 0xde, 0x9e, 0xd6, 0x0b, 0x4e, 0x0e, 0x46, 0x9b,'?"

Dick frowned, "That is completely wrong! Well, let me try again, '0x57, 0x17, 0x5f, 0x82, 0xc7, 0x87, 0xcf, 0x12, 0x5a, 0x1a, 0x52, 0x8f, 0xca, 0x8a, 0xc2, 0x1f,'"

Jane furrowed her brow, "I think I can do this one, '0xd9, 0x99, 0xd1, 0x00, 0x49, 0x09, 0x41, 0x90, 0xd8, 0x98, 0xd0, 0x01, 0x48, 0x08, 0x40, 0x91,'?"

"Wow!" dick exclamed, "You suck! Third time is the charm: '0x3d, 0x7d, 0x35, 0x24, 0x6d, 0x2d, 0x65, 0x74, 0x3c, 0x7c, 0x34, 0x25, 0x6c, 0x2c, 0x64, 0x75,'. Got it?

"I think so," Jane said, "Is it '0xdd, 0x9d, 0xd5, 0x04, 0x4d, 0x0d, 0x45, 0x94, 0xdc, 0x9c, 0xd4, 0x05, 0x4c, 0x0c, 0x44, 0x95,'?"

Dick scowled, "No, no, no! It is, '0x59, 0x19, 0x51, 0x80, 0xc9, 0x89, 0xc1, 0x10, 0x58, 0x18, 0x50, 0x81, 0xc8, 0x88, 0xc0, 0x11,' or is it, '0xd7, 0x97, 0xdf, 0x02, 0x47, 0x07, 0x4f, 0x92, 0xda, 0x9a, 0xd2, 0x0f, 0x4a, 0x0a, 0x42, 0x9f,'? That is not right. It could have been, '0x53, 0x13, 0x5b, 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,'. No that is too many letters...."

"I remember!" Jane interupted "It is '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, 0x15,'. Well, either that or '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'"

"Boy, that was harder than I thought." Dick sighed. Where were we in the code? Ah yes, '};static byte lfsr1_bits0[256]={'".

"You skipped a bunch" said Jane, "Besides, I am still not ready to look at that again. I feel like counting. In hex! '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, 0x3f, 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, 0x54, 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, 0xbd, 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, 0xeb, 0xea, 0xe4, 0xe5, 0xe6, 0xe7, 0xe0, 0xe1, 0xe2, 0xe3'"

When jane finished she looked exausted. As she collapsed, she uttered the cryptic phrase, '};static byte lfsr1_bits1[512]={'.

Dick slapped Jane back to consciousness. "You counted wrong. You are delerious. Repeat these numbers until you feel better, '0x00, 0x24, 0x49, 0x6d, 0x92, 0xb6, 0xdb, 0xff, 0x00, 0x24, 0x49, 0x6d, 0x92, 0xb6, 0xdb, 0xff,'"

Jane smiled, "Numbers always make me feel better. I will repeat those numbers, '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, 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, 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, 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, 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'"

"'};static byte bit_reverse[256]={'," Dick swore. "That gave me a headache."

But Jane still continued to repeat the numbers, So Dick was forced to drown Jane out with his own numbers, "Two can play at that game, '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, 0x5c, 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, 0x35, 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, 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff'"

At this, Jane opened her eyes wide, she began shaking and speaking in tounges. "Bloogle said, '};static void css_titlekey(byte *key, byte *im, byte invert){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]>8)&0xff] < 16)| (bit_reverse[(lfsr0>>16)&0xff]>24)&0xff];'" Jane said as she rolled her eyes. "Lograth told Jane, '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)^lfsr0)>>1)^lfsr0)>>3)^lfsr0)>>7);lfsr0 = (lfsr0>>8)|(o_lfsr0

Dick looked concerned. He tried to calm her by reciting her favorite code segment, 'combined += (o_lfsr0 ^ invert) + o_lfsr1;k[i] = combined & 0xff;combined >>= 8;}'" His voice cresendoed as he reached the height of the epic function, '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]];}'"

Jane relaxed vissibly. At that point there was a knock at the door. Dick got up to answer it.

"Oh dear," said Dick. Jane rushed to see the problem.
At the door was a a robot gone awry. "Illegal function." It said in monotone, 'int css_decrypttitlekey(byte *tkey, byte *dkey, struct 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);' Illegal function, '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;}' violates rules. Illegal function."

"Illegal function. What do you suppose it means?" wondered Jane.

"Hmm..." said Dick. "Lets see if we can fix the robot with some new instructions."

"Robot, enter command mode" Ordered Dick.

"By using this robot you agree not to reverse engineer, distribute, rent, or use this robot for purposes not explicitly..."

"Whatever," Dick interupted as he pressed the glowing accept button on the torso of the robot, "Robot, enter command mode."

"Ready for commands"

"Command: 'void css_descramble(byte *sec,byte *key){unsigned int lfsr1_lo,lfsr1_hi,lfsr0,combined;unsigned char o_lfsr0, o_lfsr1;unsigned char *end = sec + 0x800;#define SALTED(i) (key[i] ^ sec[0x54 + (i)])'" Dick paused for a breath, "'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]>8)&0xff] < 16)| (bit_reverse[(lfsr0>>16)&0xff]>24)&0xff];sec+=0x80;combined = 0;while (sec != end) {o_lfsr1 = lfsr1_bits0[lfsr1_hi] ^ lfsr1_bits1[lfsr1_lo];lfsr1_hi = lfsr1_lo>>1;lfsr1_lo = ((lfsr1_lo&1)

"Illegal command," the robot repeated. "Error code: 'o_lfsr0 = (((((((lfsr0>>8)^lfsr0)>>1)^lfsr0)>>3)^lfsr0)>>7);lfsr0 = (lfsr0>>8)|(o_lfsr0

"Hmm," said Jane. "Let me try. Robot, enter command mode"

"Ready for commands" droned the robot.

"Command: '*sec++ = csstab1[*sec] ^ (combined&0xff);combined >>= 8;}}' End command."

At this point the robot did something very frightening. It blew up. Dick and Jane shielded thier eyes. When they were finally able to see again, they were shocked by what lay before their eyes. When the robot exploded, it released thousands of fliers. The fliers flew for miles around. On each flyer the reader was greeted with the source code for a program. The program was DeCSS.

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