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Old 31st March 2009
JMJ_coder JMJ_coder is offline
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Default Obfuscated Code

This is my first exercise in code obfuscation. This is a legal C program and will compile (tested gcc and pcc) -- I'll let you guess what it does before I tell you (don't cheat by running it).

Code:
_(__,___,____,_____){(__)?printf("%d\n",____),_(__-_____,____,___+____,_____):0;}main(){_(25,0,1,1);}
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Old 31st March 2009
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I don't know what's more evil, that I can actually read that fine or that you actually compiled it.
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Old 31st March 2009
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It's valid C code.

Here's the de-obfuscated code:

Code:
/*
        a recursive fibonacci generator to print upto:
            (arg1+arg4)/arg4 fib's if (arg4 > 1 && arg4 < arg1)
            arg1 fib's if (arg4==1 && arg4 <= arg1)
        starting with the numbers arg2 and arg3 (assuming arg3 == arg2+1 || arg2 == arg3 == 1 && arg2 >= 0)
*/
fib_gen(arg1,arg2,arg3,arg4)
{
        (arg1) ?
        /* printf(...); (void) fib_gen(...); */
        printf("%d\n", arg3), fib_gen(arg1-arg4, arg3, arg2+arg3, arg4)
        :
        0;
}

main()
{
        fib_gen(25,0,1,1);
}
So, what prize am I getting?

Last edited by ephemera; 31st March 2009 at 04:21 PM.
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Old 1st April 2009
JMJ_coder JMJ_coder is offline
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Quote:
Originally Posted by ephemera View Post
It's valid C code.

Here's the de-obfuscated code:

Code:
/*
        a recursive fibonacci generator to print upto:
            (arg1+arg4)/arg4 fib's if (arg4 > 1 && arg4 < arg1)
            arg1 fib's if (arg4==1 && arg4 <= arg1)
        starting with the numbers arg2 and arg3 (assuming arg3 == arg2+1 || arg2 == arg3 == 1 && arg2 >= 0)
*/
fib_gen(arg1,arg2,arg3,arg4)
{
        (arg1) ?
        /* printf(...); (void) fib_gen(...); */
        printf("%d\n", arg3), fib_gen(arg1-arg4, arg3, arg2+arg3, arg4)
        :
        0;
}

main()
{
        fib_gen(25,0,1,1);
}
So, what prize am I getting?
I'm impressed -- you even came close to the original function name fib().

Three cheers for ephemera!
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Old 1st April 2009
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So, how did I do on my first attempt at obfuscation? Was it hard to understand? easy to decipher? etc.?
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Old 1st April 2009
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Interesting, no, and yes, lol.

All I had to do, was count the underscores to find which identifiers were which, as soon as I spotted the recursive call (~3 seconds later) it was obvious that displays a sequence of 25 numbers. The only 'hard' part was double checking if the sequence were fibonacci numbers, if you call that hard. (I stopped thinking after mentally compiling '5').


Maybe try writing a java virtual machine in brainfuck next time? hehe.
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Old 1st April 2009
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Quote:
Maybe try writing a java virtual machine in brainfuck next time? hehe.
I think anyone trying to do that will soon have an obfuscated brain.
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Old 1st April 2009
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Quote:
Originally Posted by JMJ_coder View Post
So, how did I do on my first attempt at obfuscation? Was it hard to understand? easy to decipher? etc.?
TBH, I didn't find it too hard to decipher. But, did you make this on your own?
If so, it's a good effort - in particular I liked your use of recursion!

Last edited by ephemera; 1st April 2009 at 06:10 AM.
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Old 2nd April 2009
JMJ_coder JMJ_coder is offline
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Quote:
Originally Posted by ephemera View Post
TBH, I didn't find it too hard to decipher. But, did you make this on your own?
If so, it's a good effort - in particular I liked your use of recursion!
I followed some tips from Wikipedia (e.g., use recursion instead of iteration, ?: instead of if-else, etc.), but I wrote the program and converted to obfuscated code myself.
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Old 2nd April 2009
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Cool.

Somehow obfuscation never caught my fancy.
Anyway, any code of some size and complexity without good comments is obfuscated enough for me.

You might have probably seen this one, its cool: http://www.cs.uleth.ca/~holzmann/C/C/cselfprint.html

Last edited by ephemera; 2nd April 2009 at 02:46 PM.
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Old 2nd April 2009
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if you want to use the ?: trinary/ternary operator to obfuscate things, be sure to nest them in strange and deranged ways, and slip in comma's and garbage values anywhere you can.


In my personal opinion, good code should be fairly obvious even without comments, and the comments should be free to provide 'commentary' and annotations instead of explaining away physical laziness. e.g.

Code:
/* push element onto int stack */ istk_t istkp(iskt_t *s, iskt_t *e);  

vs 

istack_t istack_push( istack_t *stk, istack_t *elem);
where the latter speaks for itself, documenting all but the 'i' part. And a proper comment in the istack module might explain what the heck the it is, and hopefully it's purpose and use should be known in a few minutes of code browsing even without it. You could say, I hate anything that I need to read more any furhter then the header file in order to use it....



Those bastardo 2000+ line procedures some people write on the other hand, just need to be drawn and quartered ;-)
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Old 30th October 2009
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I'm sensing you guys would have liked APL.

/S
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Old 30th October 2009
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I used to be an APL programmer, back in the late '70s. And through until around 1981, or so, when I moved to systems programming (today, that would be systems administration, but back then, we modified our OSes to meet requirements).

APL had some interesting capabilities, helpful for financial analysis applications (I was working for a commodities trading firm). Special keyboards and terminals were needed, however.

I did end up learning how to pronounce and spell most of the Greek alphabet, of course, as any APL programmer would. But along with Ro and Pho and Theta, we also used words to describe symbolic functions that were not Greek. The left and right arrows, for example, were called the "guzinta" and "guzouta".

One could write a line of code that would perform an operation on a large vector of numbers, that might contain, for example, twenty thousand integers, all at once. But, if the programmer misplaced a comma, rather than making a single arithmetic operation on twenty thousand numbers at once, one would instead execute twenty thousand individual operations. You'd get the same results, but thousands of times more slowly. Just from putting the comma in the wrong place.

I moved from APL to S/370 Assembler. The latter was so much clearer and easier to understand.
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Old 31st October 2009
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The number of people who have received :wq! and kkkkk messages from me, are living prove that I could never program in APL or any language needing a special keyboard, even if I think leaving near-ASCII behind is a Good Thing.
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Old 5th November 2009
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No one pointed it out; there is a possible integer overflow if the no. of fibs is > 48.
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