Cogent takes a shot at his first de-obfuscation...
So, we have three things going on: A
substitution,a transliteration,
and an eval. (Which, had I realized it, I could've found
out from the Function Nodelet.)
All three of the operations are working directly on
$_. The first, the substitution, does the
easy part: it replaces the only thing in $_, a
zero-width beginning-of-line metacharacter, with some
predetermined text:
gps%o)nbq|3++sboe~1//24*|qsjou)qbdl)#d#-75+)tjo)%o+%`*,2***gps)1//777*
+<~
Now $_ contains something useful. In a manner of speaking.
Then the code transliterates that into something truly
useful, by changing everything between ASCII 35 and
ASCII 126 to be between ASCII 34 and ASCII 125. It drops
everything down a place. Basically your simple caesar
cipher. That gives us:
for$n(map{2**rand}0..13){print(pack("c",64*(sin($n*$_)+1)))for(0..666)
+;}
which is much more readable, especially if you have an
eager newbie with something to prove ( :-) ) here to help
you out:
for $n (map {2**rand} 0..13) {
print ( pack ("c", 64*(sin($n * $_)+1)))
for(0..666);
}
For fourteen times: It takes two, raises that to the power
of some random number, and uses that as the frequency of a sine
wave. The duration of said sine wave is specified by the
666. So, for the duration (that is, for 667
iterations of a loop), the code makes a byte and sends it to
/dev/dsp. So there's your sound.
Whew!
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[d/l]
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I've always been scared to try and de-obfusticate. Now I know
I've right; keep me out of there! I'm not ready yet.Fu ..., er, simply amazing
cogent and whomever created it. Oh, and ++ to LW to, I guess.
a
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For those of us on non-/dev/dsp supported systems, anyone care to comment as to what the sound is? Is it just a sine wave, as cogent suggests but doesn't affirm? Is it just a bleep? Is it something clever? I presume it's the sine wave, but didn't see an affirmation from anyone.
-marius | [reply] |
Ah, sorry. It's actually fourteen fairly short (on my
system, at least) beeps of random pitch. I presume that
the sine waves are the (very low-level) way of making the
sound wave for each beep, but that's a guess, as I don't
really know how /dev/dsp works.
I could probably make a wav, given enough time...
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That would me moderately frightening if you could cause it to speak your name. Granted, it would no longer be a One-Liner .sig. =]
-marius
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