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Microsoft Script Encoder

Using the JavaScript compression utility, the script becomes the following:

S=”`4UL = docu`5.getEle`5ById(\”ulItems\”);

`4`2`6Docu`5`2();

for (var i=0; i < 10; i++) {

`4LI`6Ele`5(\”li\”`3LI`1`0eTextNode(\”Item \” + i)`3`2`1oLI);

}oUL`1o`2);”;for(I=6;I>=0;)S=S.replace(eval(‘/`’+I+’/g’),(“document.creat~.appendCh

ild(~Fragment~);

o~var o~ment~ = `0e~”.split(‘~’))[I--]);eval(S);

This doesn’t look smaller, but keep in mind that the original script didn’t have tabs, spaces, or new line

characters removed (the documentation suggests you use another tool for such optimization before

using this utility).

The downside to this sort of obfuscation is that its startup time is slow because of the extra interpretation

of the code. However, the overall file size can be cut significantly.

Microsoft Script Encoder (IE only)

If you are sure that your target audience will be using Internet Explorer on Windows, you can take advan-

tage of the Microsoft Script Encoder to protect your code. The Microsoft Script Encoder is command-line

program that encodes your JavaScript into completely unreadable code.

To begin, you download the utility from Microsoft (

http://www.microsoft.com/downloads/

details.aspx?FamilyId=E7877F67-C447-4873-B1B0-21F0626A6329&displaylang=en

). After

it is installed, open up a DOS command line window and use the following syntax:

screnc inputfile outputfile

The program accept numerous types of files as input, but for the purposes of encoding JavaScript the

only ones of interest are HTML files and external JavaScript (.js) files. When you specify an HTML file

for input, any code contained within an inline

element is encoded; for .js files, the entire

file is encoded.

For example, the code from the previous section gets encoded into this:

#@~^RAEAAA==-

mD~KjdP’,NK^Es+UYconOAV+snxDAX&[cJ!V&Yn:dE*i@#@&7CD,Wo.mo:nUDPxP9G1Eh xDRmM+mO+GW^E

s+UOwDlTh+ Y`*I@#@&@#@&6W.Pc-

mD~k{Ti,k~@!,F!I~b_Q#,`@#@&~,P,\lMPKJq,’~NKm;h xYc^D lY 3s+s+

YcJsrr#I@#@&~P,PGJ&Rl22 x[Z4r^Nc9W1E: xD

mM+CY KnaD1W9n`rqY h~J,_,kb#I@#@&P~P,GsMlLh xY Cawnx9/4ks9`KSq*i@#@&8@#@&@#@&KjJ

mww UN;tk^[cWwDmoh+UO*i@#@&n18AAA==^#~@

If you specified an HTML file as input, the

element is updated to have a

language

attribute

equal to

“JScript.Encoded”

; if you specified a .js file as input, you must manually add the language

attribute when referencing the file:

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