Obfuscated C programs: Introduction

If you program long enough, eventually you will run into a programming art category called "obfuscated code" or “code golf”. You can find these especially at IOCCC. In this video I introduce the concept and the basic ideas behind such design. More information below (click "Show more").

I realize the category is "obfuscated code", not "small code", but often trying to compress your code into the smallest size will also effectively obfuscate its function. I also realize that some of the individual changes I did in the video did actually _not_ result in smaller program code size, but the opposite. But the end result is still the shortest I could manage, if you remove the "int", the "return", and the space after "include".
Actual obfuscation techniques include using small and meaningless variable names, using unusual syntax constructs, redefining reserved words, adding code that appears to do one thing but does something else (or nothing at all), creating a complex machinery (such as an interpreter) to do a different task, encryption, and so on.

Source code:

Music:
- Star Ocean :: Encounter :: Motoi Sakuraba (converted into MIDI and played through OPL3 emulation through homebrew software)
- Chrono Cross :: Jellyfish Sea :: Yasunori Mitsuda

Contribute subtitles:

I got to use the word "defenestrate"!

#Bisqwit #Programming #ProgrammingPhilosophy #Tutorial #ObfuscatedCode #CProgramming

[ParadoxBassCube]

Idea/Question: is the obfuscated code faster than the normal code?

[Kniffel]

This background music really makes the code even spookier than is already is! ^^

[gubbin]

I just discovered this, and I can only describe you as the Bob Ross of programming.

[sebastianmorataboada]

0:45
_upgrade_
0:54
_upgrade_
1:16
Uhhh... _upgrade_
1:33
Whatever. _upgrade_
1:48
_🅱*_*_*_*_ _*_go BACK_*
1:57
*_aaaarghh my eyes_*
2:05
*_jFC_*
2:44
*_what the frigg did you just 🅱ring upon this cursed land_*
3:15
*_I͠t ͏i̡s ͡a̕l͏ready ̕too lat̸e.̵ T͟h̀e͜ ͟s̷ong ͝t͟ha͟t e̶ņd̸s̨ ͢th̀e̡ ͠w̧or͏l͝d̶ ̛h̸a̧s ̀alrea̡d̸y ̷bee̷n su͝ǹg.̨ ͝Em̢br͘ac͏e̢ th͜e v҉oįd̵. ҉He͝ ͢c̷om͢eeeȩs̛s̛_*

[hattrickster]

As someone with a background in Java and PHP, this is kinda how I felt when I tried to write a server in C for the first time, only 100x worse. It's like going from a power saw to a hand saw that cuts your hand off every time it isn't 100% level.

[Blue-Maned_Hawk]

This is the first time I've heard someone honestly and casually use the word "defenestrate."

[OrangeC]

I don't know about anyone else, but for me there's a certain area between obfuscated code and readable code when the code seems so elegantly designed, where it doesn't use so many obfuscated concepts as to confuse whoever is seeing it, but it also is compacted in a way that makes everything flow together concisely but beautifully. But I don't know, I haven't seen enough programs to be sure.

[ewncilo]

as someone who study the c languague for more than 4 years this so stimulating and satisfying to me

[EmielvanGoor]

I don't understand the " characters.. Why and how is this used? Do these characters mean something?

edit: OK.. I understand now.. It translates into the offset.. (You even said it in your video..!)

[WeAreCameron]

my thoughts: 1. Huh. 2. Okay. 3. Sure. 4. Wh-- err.. wh-- ????

[oEQjet]

Great introduction and breakdown to basic obfuscation techniques. Thanks for the post!

[tomhijkl]

I was blown away by this one, it took me quite a while to understand why that worked.

[Sypaka]

**Obfuscation**


Makes a 1st Person Shooter with 6 hours playtime using 30 lines of code, full HD, 3D, textured and sound.

[JTST]

This guy is legit trolling my knowledge of C.

[dzonialucard]

Wai wait, hold up
So the dude wrote a program that gets the local time and responds accordingly - IN TWO LINES??
What dark sorcery is this?

[devjock]

Amazing explanation and application. Clear, concise, and to the point. Thanks for this!

[bidyutchakraborty]

I, while trying to code a short program in C without using semicolon, came across your video and was really mesmerized. I have prepared a full length explanation of each step (... your explanations were sometimes just hints or there were no explanation at all, just like the use of & 7 instead of - '0'). I prepared this for teaching my students some very good C tricks. Thank you Bisqwit.

[GenericInternetter]

I love how his voice sounds like a computer. I like to imagine it's a computer teaching me about computers.

[mattr]

C was practically designed for obfuscation. Just use the define directive to replace all the keywords with random alphanumeric strings. You can do all kinds of meta programming to change the compiled binary as well.

[ScipiPurr]

While this is obfuscation, this is really for a specific kind of programming challenge called Code Golf where you try to write a program using a few characters as possible.

Some of my personal C/C++ code golf code:

Reads its own source file(named 'm') and prints out occurrences of characters in ascii order:
#include<set>
int main(){int a[256]{}, i;auto f=fopen("m", "r");while(i=~getc(f))a[~i]++;for(int x:a)x?printf("%c %d\n", i, x):0, ++i;}

Conway's Game of Life for the GBA using the tonc library (with identifier names shortened):
#include<tonc.h>
#define l
main(){R=1028;*P=32767;u8 x, y, s, m, p;for(;!(S=~K&1023););l M(x, y, Q()&1);for(;u8*v=(u8*)V;){F();l{for(m=-1, p=v[x+y*240], s=-p;++m<9;)s+=v[x+m%3-1+(y+m/3-1)*240];M(x, y, p?s<4&s>1:s==3);}}}