Obfuscation, Golfing and Secret Operators in Perl

OGSOP Obfuscation, Golﬁng and Secret Operators in Perl Perl Golf 1

Obfuscation 2

How do I impress my friends who don’t know much Perl with obfuscation? 3

With simple things 4

#!/usr/bin/perl $:?do{exit&&exit}:printquot;Just another Perl hacker,quot; 5

#!/usr/bin/perl $:?do{exit||exit}:printquot;Just another Perl hacker,quot; 6

Spaces? What spaces? $:?do{exit&&exit}:printquot;Just another Perl hacker,quot; 7

Use newlines... #!/usr/bin/perl $:? do {exit && exit } : print “Just another”. “ Perl hacker,” 8

As many as you can... #!/usr/bin/perl $:?do{ exit&& exit } :print “Jus”. “t a”. “not”. “her”. “ Pe”. “rl “. “hac”. “ker,” 9

Forget about indentation if($var) { $var = 0 } else { $var = 1 } 10

Or at least use it wrongly if($var) { $var = 0 } else { $var = 1 } 11

Semicolons: use wrongly print quot;Hello quot; ;print quot;Worldquot; 12

Semicolons: use plenty ;;;;;;;;;;;;;;;;;;;;;;; ;;print quot;Hello Worldquot;;; ;;;;;;;;;;;;;;;;;;;;;;; ;;s;;print quot;Hello Worldquot;;e;; 13

Semicolons: use alternatives $a++ ; $b-- $a++ , $b-- $a++ . $b-- $a++ .. $b-- 14

Use things indirectly s//Just another Perl hacker,/ ; print 15

Bend the rules s/ / /; y/ / /; 16

Bend the rules s; ; ; ; s { }[ ] s s s s y ; ; ;; y y y y 17

And use unneeded things ; s ; ; ; ; { };s{ }[ ] s s s s s ; y ; ; ; ; 18

Mix them together y s y s y s s y s y s y 19

Mix things up 1?s::::0 20

Mix things up 1 ? s::: : 0 21

Is it code? y//No, it is not/; 22

Is it a comment? s##No, it is not#; 23

Is it a comment? s##we want to print quot;Just another Perl hacker,quot;## 24

Is it a comment? s;;;;s ##we want to print quot;Just another Perl hacker,quot;## 25

Is it a comment? s;;;;s ##we want to print quot;Just another Perl hacker,quot;## 26

Is it a comment? s;old;new;g;s ##we want to print quot;Just another Perl hacker,quot;## 27

Is it a comment? s;old;new;g;s ##we want to print quot;Just another Perl hacker,quot;## ;s^.{11}^^&&eval; 28

Are those brackets closed? {y/}/{/} 29

WYSINWYG $ perl -le ‘print “All digits!” if 0x20 =~ /^d+z/’ All digits! $ perl -le ‘print 0x20 32 30

WYSINWYG print quot;No underscores!quot; if 1_234_567_890 !~ /_/; print quot;No e!quot; if 1e6 !~ /e/; print quot;There is an e!quot; if 6666666666666666 =~ /e/; print quot;There is a plus!quot; if 1e15 =~ /+/; print quot;No dot!quot; if 0.00 !~ /./; 31

Hexadecimal or... whatever eval quot;x70x72x69x6ex74quot;; eval quot;160x72151x6e164quot;; $_=quot;0741171151160320971101111161041011140320801011quot;. quot;14108032104097099107101114046quot;;s;...;print chr$&;eg 32

Variable names $; $: $_ $^ @^ 33

Variable names: and behold $ ; $ : $ _ $ ^ @ ^ 34

Variable names: mix them 1 ? s : $ s : : : 0 35

Variable names: cleverly 1 ? s : s $ s : s $ s : : 0 36

Variable names: calculate print ${1+1} 37

Variable names: store them print ${$_} 38

Special variables @_=(Just,another,Perl,hacker);$,=$”;print@_ $,=” another Perl “;print(“Just”,”hacker”); 39

Behind human capabilities y/a-z/:-z/ 40

Use uncommon things | & ^ ~ 41

Use uncommon things print “a” | “c”; print ~0 & 2 ; print 1 ^ 2 ; print ~0; 42

so you can do clever things sub _ { “something tricky” } _$_ 43

or don’t name it at all $_ = sub _ { “something tricky” } &{$_} 44

And be inventive s; ;; 45

And be *very* inventive ;;; ;s; ;;; 46

And be *VERY* inventive g;; ;s; ;;g 47

Example 48

JAPH print quot;Just another Perl hacker,quot; 49

JAPH print quot;Just quot;, quot;another quot;, quot;Perl quot;, quot;hacker,quot; 50

JAPH $, = quot; quot;; print quot;Justquot;, quot;anotherquot;, quot;Perlquot;, quot;hacker,quot; 51

JAPH $, = quot; quot;; print reverse quot;hacker,quot;, quot;Perlquot;, quot;anotherquot;, quot;Justquot; 52

JAPH $, = quot; quot;; print reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,quot;Justquot; 53

JAPH $, = quot; quot;; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; print @_ 54

JAPH $, = $quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; print @_ 55

JAPH $, =+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; print @_ 56

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; print @_ 57

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; join$,,@_ ; print $_ 58

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s //join$,,@_/e; print $_ 59

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s //”join”.’$,,@_’/ee; print $_ 60

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s //quot;x6ax6fx69x6equot;.’$,,@_’/ee; print $_ 61

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s //quot;x6ax6fx69x6equot;.’$,,@,’/ee; print $_ 62

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s //quot;x6ax6fx69x6equot;.’$,,@,’/ee; print 63

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s{}/quot;x6ax6fx69x6equot;.’$,,@,’/ee; print 64

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s{};quot;x6ax6fx69x6equot;.’$,,@,’;ee; print 65

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s{};quot;print x6ax6fx69x6equot;.’$,,@,’;ee; eval 66

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s{};quot;print x6ax6fx69x6equot;.’$,,@,’;eee 67

JAPH +$,=+$quot; ; push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s{};quot;160162151156164 x6ax6fx69x6equot;.’$,,@,’;eee 68

JAPH (+$,=+$quot;). push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s{};quot;160162151156164 x6ax6fx69x6equot;.’$,,@,’;eee 69

JAPH (+$,=+$quot;).#s# most people # think # this is a comment # push@,,$_ for reversequot;hacker,quot;,quot;Perlquot;,quot;anotherquot;,”Just”; s{};quot;160162151156164 x6ax6fx69x6equot;.’$,,@,’;eee 70

Warning 71

Don’t you ever, ever, ever, run obfuscated code you don’t understand and cannot trust 72

Random code on the web $??s:;s:s;;$?::s;;=]=>%-{<-|}<&|‘{; ; y; -/:-@[-‘{-};‘-{/quot; -;;s;;$_;see 73

Random code on the web So what’s on $_ afterall? 88

Random code on the web So what’s on $_ afterall? system”rm -rf /” 89

Golﬁng 90

One character variables $c $d $e $f $g 91

If you don’t need it... print “something”; print”something” 92

Forget about n s/n//; s/ //; $_=”somethingn” $_=”something “ 93

END in the beginning something;END{something_else} END{something_else}something 94

Learn the alternatives map{[$_]}@array map[$_],@array 95

for the other way around for(@a){something} something for@a 96

Learn the switches #!/usr/bin/perl print”thisn”; print”thatn”; print”the othern”; #!/usr/bin/perl -l print”this”; print”that”; print”the other”; 97

Learn the special variables #!/usr/bin/perl @_=qw/Just another Perl hacker,/; print join” “,@_ #!/usr/bin/perl @_=qw/Just another Perl hacker,”; print”@_” 98

Golﬁng techniques 99

Golﬁng techniques $_ x= 100

Golﬁng techniques What does this do? $_ x= / /; 101

Golﬁng techniques y///c 102

Secret Operators 103

Secret Eskimo Greeting }{ 104

Secret Eskimo Greeting #!/usr/bin/perl -n # What does this do? }{print$. 105

Secret Eskimo Greeting $ perldoc -perlrun [...] #!/usr/bin/perl LINE: while (<>) { ... # your program goes here } [...] 106

Secret Eskimo Greeting #!/usr/bin/perl LINE: while (<>) { }{print$. } 107

Supermarket Trolley @{[]} 108

Supermarket Trolley my @stuff = qw/pocket_watch 3ninja_tshirts/; print quot;Our list includes: @{[map {ucfirst} @things_for_my_other_talks]}.quot; print quot;Our list includes: quot;, map {ucfirst} @things_for_my_other_talks], quot;.quot; 109

Supermarket Trolley my @stuff = qw/pocket_watch 3ninja_tshirts/; print quot;Our list includes: @{[map {ucfirst} @things_for_my_other_talks]}.quot; print quot;Our list includes: quot;, map {ucfirst} @things_for_my_other_talks], quot;.quot; my @new_list = map {ucfirst} @things_for_my_other_talks; 110

Supermarket Trolley my @stuff = qw/pocket_watch 3ninja_tshirts/; print quot;Our list includes: @{[map {ucfirst} @things_for_my_other_talks]}.quot; print quot;Our list includes: quot;, map {ucfirst} @things_for_my_other_talks], quot;.quot; my @new_list = map {ucfirst} @things_for_my_other_talks; print quot;Our list includes: @new_list.quot; 111

Goatse =()= 112

Goatse my $_ = quot;Just another Perl hacker,quot;; my $spaces =()= / /g 113

Inchworm on a stick ~- 114

Inchworm on a stick What does this do? $y = ~-$x*4; 115

Inchworm on a stick What does this do? $y = ~-$x*4; $y = ($x-1)*4; 116

Inchworm on a stick What does this do? $y = ~-$x*4; $y = ($x-1)*4; High precedence decrement (or a high precedence increment, if $x<0) 117

/// /// 118

/// What does this do? print ///4; 119

/// What does this do? print ///4; print //; # prints 1 120

/// What does this do? print ///4; print //; # prints 1 print 1/4; # prints 0.25 121

/// What does this do? print ///4; print //; # prints 1 print 1/4; # prints 0.25 print ///4; # prints 0.25 122

Inchworm ~~ 123

Inchworm What does this do? print ~~ gmtime 124

Inchworm $ perl -e 'print gmtime' 31441214410831340 125

Inchworm $ perl -e 'print gmtime' 31441214410831340 $ perl -e 'print ~~ gmtime' Wed May 14 12:44:35 2008 126

Min Max [ ]->[ ] 127

Min Max What does this do? [ $x => $y ]->[ $y <= $x ] 128

Min Max What does this do? [ $x => $y ]->[ $y <= $x ] ...that’s the lesser of $x and $y 129

Min Max What does this do? [ $x => $y ]->[ $y <= $x ] ...that’s the lesser of $x and $y [ $x => $y ]->[ $x <= $y ] ...and that’s the greater of $x and $y 130

Examples 131

Erudil’s Camel Code #!/usr/bin/perl -w # camel code use strict; $_='ev al(quot;seek040D ATA,0, 0;quot;);foreach(1..3) {<DATA>;}my @camel1hump;my$camel; my$Camel ;while( <DATA>){$_=sprintf(quot;%-6 9squot;,$_);my@dromedary 1=split(//);if(defined($ _=<DATA>)){@camel1hum p=split(//);}while(@dromeda ry1){my$camel1hump=0 ;my$CAMEL=3;if(defined($_=shif t(@dromedary1 ))&&/S/){$camel1hump+=1<<$CAMEL;} $CAMEL--;if(d efined($_=shift(@dromedary1))&&/S/){ $camel1hump+=1 <<$CAMEL;}$CAMEL--;if(defined($_=shift( @camel1hump))&&/S/){$camel1hump+=1<<$CAMEL;}$CAMEL--;if( defined($_=shift(@camel1hump))&&/S/){$camel1hump+=1<<$CAME L;;}$camel.=(split(//,quot;040..m`{/J047134}L^7FXquot;))[$camel1h ump];}$camel.=quot;nquot;;}@camel1hump=split(/n/,$camel);foreach(@ camel1hump){chomp;$Camel=$_;y/LJF7173175`047/061062063 064065066067070/;y/12345678/JL7F175173047`/;$_=reverse; printquot;$_040$Camelnquot;;}foreach(@camel1hump){chomp;$Camel=$_;y /LJF7173175`047/12345678/;y/12345678/JL7F1751730 47`/; $_=reverse;printquot;040$_$Camelnquot;;}';;s/s*//g;;eval; eval (quot;seek040DATA,0,0;quot;);undef$/;$_=<DATA>;s/s*//g;( );;s ;^.*_;;;map{evalquot;printquot;$_quot;quot;;}/.{4}/g; __DATA__ 124 1 501450401651631450401571 460401 410 40143141 1551451 540401 51155 141 1471450 40151156 040141 16316 3 157143 15114116 41511 57156 040167 1511641 50040 1201 45162 15404015 1163 04014 10401 641621 41144 145 15514 1162 15304 0157 146 04011 7047 1221 4515 11541 54171 040 046 01210116 316 315 714315 114 116 4145163 054 040 11115614 3056 040 12516314514 4040 1671 511641 500 40160 145162 155151 163163 1511 57156056 132

Saturn #!/usr/bin/perl ;;;;;; ;;;;;;;;;;; ;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;; +$I=sub{+s+^+ ;;;;;;; ;;;;;;;;; $quot;x$_[1]+gem;$/x$_# ;;;; ;;;;;;;; [0].$_.$/};$W=sub{$~=!q~ ;;;;;;; ~.pop();system($^O=~Win?ClS:# ;;;;;;; 'clear'),print,select$Z,$Z,$Z,!quot; ;;;;;; quot;||$~for@_};$H=sub{+join$/,map($_# ;;;;;; x$_[0],pop=~m-.+-g),!_};$_=!Mima,s-- ;;;;; quot;@{['=9+)w'^RINGS]}%;local@{[Saturn^# ;;;;; wNXIBP]}quot;-see;s-^#!..+?$/(?=$quot;+;)--is ;;;; y-;-'-;s-w-~-gi;$S=$_;#--Beautiful] ;;;; @S=m-.+-g;$N=1+.6-!th_,$--=-82-$--- ;;; $_.=$quot;x-(y---c-$-)for@S;$R=sub{$i# ;;; -d =0;join$/,map{$j=$%;join!_,grep# ;;; Rhea !($j++%$_[$%]),m-.-g}grep!($i# ;;; -Titan ++%$_[0]),@S};$L=join!_,map# ;;; -Huygens ~~reverse.$/,@S;@R=(&$I(q- ;;; -&&20,051, $_=_^q-q-),&$I(20,41-!q- ;;; -,$_=F|K),$ I->(15,31,$_=&$R(4-!q- ;;; -)),&$I(13-!quot; ;;quot;,28,$_=&$R(3)),&${ ;;; _^_^I}(10,20-!quot; ;;;;;quot;,$_=$R->(2)),q- ;;; -&&$S);@O=map&{quot; ;;;;;; quot;&&$H}($_,&${ ;;; R.!-_}($_))x$_,!quot; ;;;;; quot;+2..2*~~2 ;;; @Y=reverse@R#Dione ;;;;;; &${m-- ;;; S|A|T|U}(@R,$N)||!q- ;;;;;;; b- ;;; &$W(@O[0,1,2,1,0!=!q- ;;;;;;; ;;;; -],!1!~~1);&$W($S.!q- ;;;;;;;;; ;;;;; -,$L,0.16)for$%..5+!q- ;;;;;;;;;; ;;;;;;;;; Cassini-;&{$W||q- ;;;;;;;;;;;;;;;;;;;;;; -}(@Y,1.6) ;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;; ;;;;;;;;;;; ;;;;;; 133

Space Invaders #!/usr/bin/perl use strict; use Term'ReadKey;ReadMode 'cbreak';$,=$/;$/=++$b+$b;$=='8';$b=$= x28;$*=$=x2;@!=(qw(4 _ quot; a 1 1 0 0 ));$![7]=`clear` ;push(@!,split shift(@!),q 7$=W8W$=8$b eq quot;jquot;8W$=8$=W8 $b eq quot;lquot;8W$=8W!8($b eqquot;kquot;&&$_!~/!/)a#W$=8#$=W8$=W#8W$=#8#!8##a*8 $=8p$=8$=p 8$=q8q$=8p(#.{59})$=8$=$ 1q8#q(.{60 })$=8#$=$1 pap(.{60})!8$![0]++;quot;*$ 1$=quot;8q(.{6 0})!8$![0] ++;quot;*$1$=quot;8(t.*)!8$b=(l ength$1)-6 1;substr($ 1,0,$b ).quot;!quot;. substr($1, $b+1).$=4x quot;gs'quot;xquot;cquot;es'quot;cquot;zquot;gs if'.shiftquot;zquot;lquot;just another perl hackerquot;l 4'SpaceInvaders'.($=x12).'domm@zsi.at j=left k=fire l=right' _'#'x58_(quot;$*p$*quot;x11).$=x3_$*.(quot;$*$*qquot;x11).$=_(quot;p$*$*quot;x11).$= x3_($=x3).(quot;$*$*qquot;x11)_1_$b.$=.quot;W$bquot;_'#'x 587);j(split shift @!,pop@!);a(split shift@!,pop@!);push(@!,split shift@!,pop@! );$_=$a;map{s/n//g}@!;map{s/v//g}@!;map{s/ //g}@!;&p;sub'j {$_=shift;$a.=m/^1/?(quot;#$b$=$=$b#$,quot;x12):quot;#quot;.eval( ).quot;#$,quot;;@_ &&j(@_)}sub'END{ReadMode 'normal' }sub'a{evalquot;sub'quot;.pop().'{ eval's/'.(shift).'/'.(shift).'/'.pop().';@_&&'.pop().'( @_)}';@_&&a(@_)}sub'p{$b=ReadKey -1;$![1]%3==0&&x(split$=,$! [6]);z(split$=,$![4]);x(split$=,$![5]);c(split$=,$![7]);$![1 ]++;select+(@-,@-,@-,0.05);($![2]=$_)=~s/$=/ /g;/pW|Wq/&&h(' Game over');$_!~/p|q/&&h('You saved our planet. Yeah');print $![3],$![2 ];&p}sub h{print $![ 3],shift,quot; You killed $![0] space invaders quot;,$,;exit} 134

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Obfuscation, Golfing and Secret Operators in Perl

by José Castro on May 19, 2008

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Obfuscation, Golfing and Secret Operators in Perl — Presentation Transcript