Obfuscated Code

December 21, 2004 4:34 PM
Obfuscated code used to fascinates me and I've been trying hard to understand the ultra popular cryptic program that generates the verses of the poem, "The 12 days of Christmas."

Here's the perfectly executable valid C code borrowed from Wikipedia:

#include <stdio.h>
main(t,_,a)char *a;{return!0<t?t<3?main(-79,-13,a+main(-87,1-_,
main(-86,0,a+1)+a)):1,t<_?main(t+1,_,a):3,main(-94,-27+t,a)&&t==2?_<13?
main(2,_+1,"%s %d %d\n"):9:16:t<0?t<-72?main(_,t,
"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l,+,/n{n+,/+#n+,/#\
;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l \
q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# \
){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' \
iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c \
;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# \
}'+}##(!!/")
:t<-50?_==*a?putchar(31[a]):main(-65,_,a+1):main((*a=='/')+t,_,a+1)
  :0<t?main(2,2,"%s"):*a=='/'||main(0,main(-61,*a,
"!ek;dc i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry"),a+1);}

Another interesting example at The International Obfuscated C Code Contest.

Ever heard of the BrainF***¹ language? It's an esoteric programming language that has only 8 instructions but can compute almost anything that can be computed. And I thought I had trouble naming things.

Programs that decrypt themselves and execute fascinates me and I had employed that technique to hide a simple password in a client executable javascript file. It kept out the people who thought clicking "View Source" was smart, but obviously others broke through. Nevertheless, wrapping the encrypted code in a decrypting function which is wrapped around code that can execute code is a popular security through obscurity technique.

CategoryProgramming

^[1] *** = hpx².
^[2] Scrambled using an ultra popular Caesar cipher to keep in spirit with the post topic.