explain obfu code

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: explain obfu code by dragonchild (Archbishop) on Oct 02, 2001 at 01:17 UTC
Here're the steps I'd take: Get rid of all the comments. Run it to make sure I didn't break anything Put a newline after every single semi-colon Run it to make sure I didn't break anything Start to fix the logic, renaming variables and the like Run it after every single edit, to make sure I didn't break anything Start getting rid of filler-code. Run it after every single edit, to make sure I didn't break anything A few tricks to keep in mind: `)=5;` is a way of making a variable named $ and setting it equal to 5. Order of operations is critical. Delimiters don't have to be slashes. That should be enough to get you started. ------ We are the carpenters and bricklayers of the Information Age. Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.	[reply] [d/l]
Re: explain obfu code by maverick (Curate) on Oct 02, 2001 at 01:53 UTC
You could also run it through Deparse to make it look a lot less ugly...that would by my first step. perl -MO=Deparse script.pl Yields: `++$\|; undef $/; $_ = $e \|\| <ARGV>; tr/+-.<>[]//cd; foreach $a (']}', '[while($p[$p]){', '-$p[$p]--', '+$p[$p]++', ',$p[$p +]=ord(getc)', '.print(chr($p[$p]))', '<$p--', '>$p++') { s/\Q${\substr($a, 0, 1);}\E/${\substr($a, 1);}\n;/g; } eval $_;` [download] Yick! What is this program supposed to do anyway? Updated Here's my second pass at looking at this. Look at the elements in the foreach loop. The left most character of the element is what is looked for in the replacement and the rest of the element it what a match is replaced with. This input `[ < - ]` [download] Produces this output `while($p[$p]){ ;$p-- ;$p[$p]-- ;} ;` [download] Could this be a home brew macro language parser? jeffa agree's with this idea. /\/\averick perl -l -e "eval pack('h*','072796e6470272f2c5f2c5166756279636b672');"	[reply] [d/l] [select]
Re: Re: explain obfu code by japhy (Canon) on Oct 02, 2001 at 03:20 UTC
It's an interpreter for Brainfuck. _____________________________________________________ Jeff`[japhy]`Pinyan: Perl, regex, and perl hacker. `s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;`	[reply]
Re: Re: explain obfu code by broquaint (Abbot) on Oct 02, 2001 at 17:21 UTC
Try piping this into it - `+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++.>++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++.>+++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++.>++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++.>+++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++.>++++++++++.>-<` [download] There are more elegant ways of putting that, but it's brainfuck which is rarely elegant anyways. HTH broquaint Note: the above spew was (as you've probably guessed) created by yet another BF script (which can be found here).	[reply] [d/l]
Interesting... by Rhose (Priest) on Oct 02, 2001 at 18:36 UTC
I had never heard of BF -- I guess you do learn something new every day. Anyway, in the spirit of BF Golf, I shortened your code. Grins `+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++.---------.----- --------------------------.++++.+++++++++++++++++++++++++++++ +++++.` [download]	[reply] [d/l]
Re: explain obfu code by perrin (Chancellor) on Oct 02, 2001 at 01:52 UTC
Perltidy is often helpful when dealing with obfuscated code.	[reply]
Re: Re: explain obfu code by echo (Pilgrim) on Oct 02, 2001 at 01:57 UTC
and so is B::Deparse.	[reply]