====== How to sign an applet ======
^versions^ALL^
|contributors|[[user:irag]]|
|started on|2008-09-20 09:53|


By default Java applications are considered safe to run, or in Java speak //trusted//, since they are executed explicitly by users on their own computers. Applets by comparison are considered //untrusted// since they are initiated automatically in the browser. This restriction prevents applets from doing certain things, such as loading content from a different domain than the one hosting the applet. The error generated will look something like://java.security.AccessControlException: access denied (java.net.SocketPermission some URL here connect,resolve).//
 To override this restriction, you can can //sign// the applet.

There are a couple different approaches to signing an applet, but they each involve connecting a certificate to your jar file. Certificates are digital signatures that incorporate a public key with some identity. There are companies (Certificate Authorities) that sell certificates for hundreds of dollars, but it is also possible to create a self-sign certificate for free, which is the approach shown below. 

The //select_image// sketch below the instructions attempts to load an image from your computer using a standard file browser. When run as an applet, it **needs** to be signed. 









===== Instructions =====

Assume you have a sketch named **loadImage.pde**


  - Export your sketch as an applet, creating loadImage.jar. (Please note that if core.jar was also created, you have "Use multiple .jar files when exporting applets" checked in Processing's preferences window. I recommend unchecking this setting and re-exporting the sketch. Otherwise you'll need to sign both .jar files.
  - Open a terminal program and navigate to the applet directory where loadImage.jar is located.
  - type ''keytool -genkey -keystore pKeyStore -alias p5geek''
  - type ''keytool -selfcert -keystore pKeyStore -alias p5geek''
  - type ''jarsigner -keystore pKeyStore //loadImage//.jar p5geek''
  - Upload your applet
 

* obviously replace //loadImage// with the real name of your .jar file



===== Source code =====

<code processing>
/**
How to sign an applet taken from http://processinghacks.com/hacks:signapplet
@author Ira Greenberg
*/

/* To run this sketch as an 
 applet, it MUST be signed */
void setup(){
  size(400, 400);
  PImage img;
  String imgName = selectInput();
  img = requestImage(imgName);
  image(img, 0, 0);
}
</code>







===== Related Links =====
Please list any links you think are essential reading related to this hack:

[[http://processing.org]]