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Comment by s-macke | Hacker News Reader

Yes, you haven’t tried it. LLMs are actually awesome at deobfuscation, but terrible at obfuscation. They just can’t do it yet.

They also lack the creativity needed for those entries. Obfuscation is only one part of it. Coming up with the idea is another. Many entries also have special qualities that make them true works of art.

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They should train on some of my colleagues code - they have an inate skill of turning anything simple and clear into a mindboggling mess

Lol you're so much smarter, nice

> They just can’t do it yet.

Have you tried it or are you guessing this?

Yes, I’ve tried it. For example, this was my winning entry from a year ago [0]. The LLM only performs trivial obfuscation, not advanced transformations.

For example:

  if (x == 1 || x == 2) { ...

can be transformed into:

  if (!(2+x*x-3*x)) { ...

An LLM will do this if you explicitly ask it to, but not on its own.

[0] https://github.com/ioccc-src/winner/blob/master/2024/macke/p...

One of the main instruments of obfuscation (and the way to get more out of the size constraints) is making the code as short as possible, so in that example you'd prefer

    if (!(x/2-1)) { ...

EDIT: Oops, confused the original with x==2 || x==3. Instead, we can use !(x-1>>1), which precedence rules parse as !((x-1)>>1).

I checked this in an online C-compiler and it is not equivalent to x==1 | x==2.

this statement is equivalent to x==2 | x==3.

For example, x=3, 3/2 = 1 then 1-1 = 0 so that !(0) is 1 or true. Also for x=1, 1/2 = 0 then 0-1 = -1 and !(-1) = 0 or false.

I agree with your point in general though about size constraints.

It's pretty easy to see what that does though, even if it is shorter. Wouldn't the other approach be more obfuscated?

extrano84 already found some errors but also 0 will fail and if x is int (instead of unsigned int) all negative numbers will also fail (but so will the original s-macke obfuscation as well).

Not sure what you mean by advanced transformations but I got these versions from ChatGPT without explicit instructions.

  if(x-1<2&&x)...
  if((1<<x)&6)...
  if(x<3&x)...
  if(3%x&&x<3)...
  if(!((x-1)*(x-2)))
  if(!(x^1|x^2))...
  if(!(x*x-3*x+2))

(1) fails for negative numbers

(2) fails for (x % 32 in [1, 2]) due to UB

(3) fails for x == 2

(4) crashes for x == 0

(5) is the same polynomial, only factorized

(6) always returns 0

(7) is the same polynomail reordered

But this works for any value of x:

  x<2==2-x

or for something shorter:

  x<3&x>0

but that's not bery obfuscated

But then we all know that LLM has come a long way since one year ago.

Are you sure they still can't do it?

Just two months ago I tried to write a short K code with Claude Opus 4.6, only to find that while it had sufficient knowledge about K vocabularies it didn't try to make good use of them. K is, while slightly obscure and obfuscated, a real programming language and certainly better known than obfuscated programming. I don't have high hope for IOCCC-grade obfuscation.

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