Lair Of The Multimedia Guru


Decrypting (old analog) PayTv

A really long time ago, 1997 or maybe it was even a little earlier i wrote a program to decrypt the at that time used analog pay tv systems videocrypt and nagravision sadly i was too afraid of legal issues at that time so i never released either source or binary, well both systems are AFAIK dead nowadays, the old code hasnt been touched since 2000, doesnt compile with any compiler i have, so i thought its the perfect time for finally releasing that trash

When was the first working version born?

well i dont know, the oldest file i could find was a 2do list from 1997 which contains notes about improving videcrypt and nagravision decoding so these must have been working already …

Does it contain any cryptografically new knowlegde about the systems

no, before the nagra PRNG was reverse engeneered i belived that the PRNGs both systems used would be very secure and there would be no point in “looking” at their output, afterwards besides feeling silly as even a blind man would have noticed how the nagra PRNG works (its just permutating 256 5bit values in trivial 32768 ways, 127 only if we ignore new[x]= old[x+C])
i tried to look at the videocrypt PRNG output but failed to find anything, 2 cutpoint sequences where either different and their difference random or there where exactly equal, which happened either commonly (repeating after an hour or so) or never, depending upon when you recorded them, i also failed to find any other relations in the sequences …

Is this clean ANSI C code?

its ultra messy DJGPP-GCC-DOS-C code, i started to clean it but gave up, a patch with my unfinished cleanup work is included for the insane. with the patch a few files compile under current gcc-linux

what else does it do? could it make coffee?

Theres some teletext decoding code, some half working sync suppression decoder (with unmodified hardware) and probably a few other things i dont remember, after all it doesnt compile and i dont have my matrox meteor card here (which was the only card it supported, as that was what i had)

did you port it to java?

yes, i ported part of it to java a really long time ago, why i did that iam not sure anymore, was i seriously beliving the sun propaganda that java was a useable general propose programming language?i guess my excuse is that my previous java code at that time where just tiny applets & applications where the java-effect isnt so noticeable
the java version was even with hand coded mmx over jni about 3 times slower, there where ~1sec garbage collector pauses every 30secs or so and after 15min the computer needed a hard reset (yeah that was even without any mmx/jni)

download this crap\h\h\h\hmasterpiece



GPL but what do you want to do with it?!

Filed under: Cryptanalysis — Michael @ 14:37

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