having trouble using signed java applet

Darren · Sep 20, 2005

Hi i wrote an applet recently and posted a request here for help in allowing
it to open a socket. I got some excellent info on creating self signed jar
files that allow me access to functions normally prohibited to java applets.
Now i've follwoed the instructions but now my heml code has trouble
accessing the jar file.

here's the steps i took in creating the self signed jar file.
firstly i created the certificate
c:\j2sdk1.4.2_06\bin\keytool -genkey -keyalg rsa -alias dazkey
c:\j2sdk1.4.2_06\bin\keytool -export -alias dazkey -file dazsuncert.crt
then i created the jar
c:\j2sdk1.4.2_06\bin\jar cvf c:\applets\Helloserver.jar
c:\applets\Helloserver.class
then signed and verified it
c:\j2sdk1.4.2_06\bin\jarsigner c:\applets\Helloserver.jar dazkey
c:\j2sdk1.4.2_06\bin\jarsigner -verify -verbose -certs
c:\applets\Helloserver.jar

to test it i put the jar file and html file on there own on my website

Helloserver.htm
Helloserver.jar

the content of the html file are as follows
<HTML>
<HEAD>
</HEAD>
<BODY>
<CENTER>
<APPLET
codebase = "."
archive = "Helloserver.jar"
code = "Helloserver.class"
width = "500"
height = "300"</APPLET>
</CENTER>
</BODY>
</HTML>

The java consol stated the following
Java Plug-in 1.5.0_04
Using JRE version 1.5.0_04 Java HotSpot(TM) Client VM
User home directory = C:\WINDOWS

load: class Helloserver.class not found.
java.lang.ClassNotFoundException: Helloserver.class
at sun.applet.AppletClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadCode(Unknown Source)
at sun.applet.AppletPanel.createApplet(Unknown Source)
at sun.plugin.AppletViewer.createApplet(Unknown Source)
at sun.applet.AppletPanel.runLoader(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.io.IOException: open HTTP connection failed.
at sun.applet.AppletClassLoader.getBytes(Unknown Source)
at sun.applet.AppletClassLoader.access$100(Unknown Source)
at sun.applet.AppletClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
... 10 more
Exception in thread "Thread-4" java.lang.NullPointerException
at sun.plugin.util.GrayBoxPainter.showLoadingError(Unknown Source)
at sun.plugin.AppletViewer.showAppletException(Unknown Source)
at sun.applet.AppletPanel.runLoader(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
java.lang.NullPointerException
at sun.plugin.util.GrayBoxPainter.showLoadingError(Unknown Source)
at sun.plugin.AppletViewer.showAppletStatus(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "thread applet-Helloserver.class"
java.lang.NullPointerException
at sun.plugin.util.GrayBoxPainter.showLoadingError(Unknown Source)
at sun.plugin.AppletViewer.showAppletException(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

now when i put the class file instead of the jar and removed the jar file
and the archive tag from the html file the class loads ok but again i get
the security problems.

Help

Roedy Green · Sep 20, 2005

archive = "Helloserver.jar"
code = "Helloserver.class"

You don't post a class without a package. That is only for
experimenting. I suspect signing presumes packages.

Roedy Green · Sep 20, 2005

codebase = "."

that does not do anything. Just leave it out.

Roedy Green · Sep 20, 2005

archive = "Helloserver.jar"
code = "Helloserver.class"

An Applet should always have a package. Also be careful. Java and some
servers are case sensitive. To avoid getting bitten, I consistently
use a convention:

1. packages are always lower case.
2. jar names are always lower case.
3. classes always start with a capital letter.

e.g.

code="com.mindprod.wassup.Wassup.class"
archive="wassup.jar"

Roedy Green · Sep 20, 2005

load: class Helloserver.class not found.

look in your jar. Is the class in there with no package, spelled
EXACTLY like that including case. Use Winzip or the like to peek.

JarLook will produce a list of what is in a jar.

see http://mindprod.com/products1.html#JARLOOK

Roedy Green · Sep 20, 2005

now when i put the class file instead of the jar and removed the jar file
and the archive tag from the html file the class loads ok but again i get
the security problems.

Obviously. You can't sign a class file, only a jar.

Darren · Sep 20, 2005

Roedy Green said:
You don't post a class without a package. That is only for
experimenting. I suspect signing presumes packages.

by package you mean like 'java.net' or 'java.io'?
does my package name need to be in a similar format?
how do i include it in my html applet tag?

Darren · Sep 20, 2005

Roedy Green said:
that does not do anything. Just leave it out.

Will do. Wasn't sure if java was finnicky about such things.

Darren · Sep 20, 2005

Roedy Green said:
An Applet should always have a package. Also be careful. Java and some
servers are case sensitive. To avoid getting bitten, I consistently
use a convention:

1. packages are always lower case.
2. jar names are always lower case.
3. classes always start with a capital letter.

e.g.

code="com.mindprod.wassup.Wassup.class"
archive="wassup.jar"

How is the com.mindprod.wassup constructed. Is it something you made up on
bespoke or is there a reason the syntax is like that? Also when i put
package in my applet. e.g 'package helloserver;' it creates a subdirector
called helloserver and i suspect if i were to call my package
"com.g7wap.helloserver" it would create a directory tree starting with com
then one below would be g7wap and the one below would be helloserver. if
this is the case then how would i reflect this in the jar archive? would jar
create the directory structure automatically based on the "package" entry in
the applet?

Oliver Wong · Sep 20, 2005

Darren said:
by package you mean like 'java.net' or 'java.io'?
does my package name need to be in a similar format?
how do i include it in my html applet tag?

Here's a tutorial on how to use packages in java:

http://jarticles.com/package/package_eng.html

- Oliver

Roedy Green · Sep 21, 2005

by package you mean like 'java.net' or 'java.io'?
does my package name need to be in a similar format?
how do i include it in my html applet tag?

See http://mindprod.com/jgloss/package.html
http://mindprod.com/jgloss/applet.html

also see http://mindprod.com/jgloss/gettingstarted.html

You need an intro textbook of some sort, even a very out of date one
to explain these basic.

Roedy Green · Sep 21, 2005

How is the com.mindprod.wassup constructed. Is it something you made up on
bespoke or is there a reason the syntax is like that?

I own the domain mindprod.com. So I name all my packages
com.mindprod. That insures they will be globally unique.

wassup is the name of a package, a group of related classes.

Wassup in the name of my Applet and the main class, the one that is
used to get the whole ball rolling.

so archive="wassup.jar" ( to contain all the wassup class files)
code="com.mindprod.wassup.Wassup" to tell the browser the package
and class name of my main class.

If you want to examine the code and html, see
http://mindprod.com/applets/wassup.html

I have posted all kinds of applets you can play with and modify.

Roedy Green · Sep 21, 2005

called helloserver and i suspect if i were to call my package
"com.g7wap.helloserver" it would create a directory tree starting with com

Your package name reflects your directory structure.

What I am about to say is not completely true, but true enough for
your level:

I create a directory structure like this:

C:\com\mindprod\wassup

Than I put my Wassup.java file there.
Then I compile to create Wassup.class in that same directory
then I jar to create wassup.jar
then I sign the jar (a step you can leave out for now).
then I post that on my website or run the jar locally.

I usually give my Applet a main method so I can run it as as
application to debug it without the fuss of a browser.

If you use an IDE it creates the package directories for you in
project directories. You organise your related packages into
projects.

Roedy Green · Sep 21, 2005

jar
create the directory structure automatically based on the "package" entry in
the applet?

not quite automatically, but the jar had bloody BETTER reflect the
package structure with the member name hierarchy. See
http://mindprod.com/jgloss/jar.html
http://mindprod.com/jgloss/jarexe.html
http://mindprod.com/jgloss/classpath

For all this compiling, jaring etc, sooner or later you will want to
use ant scripts. You are welcome to use any of mine posted at
http://mindprod.com/products.html
and strip out what you don't need.

Darren · Sep 21, 2005

Roedy Green said:
See http://mindprod.com/jgloss/package.html
http://mindprod.com/jgloss/applet.html

Lovely site that.

path like a directory structure, got it

also see http://mindprod.com/jgloss/gettingstarted.html

You need an intro textbook of some sort, even a very out of date one
to explain these basic.

I have a book on java 2 somewhere, probably in the attic. Bloody hell i hate
the dark.

Darren · Sep 21, 2005

Roedy Green said:
com

Your package name reflects your directory structure.

What I am about to say is not completely true, but true enough for
your level:

I create a directory structure like this:

C:\com\mindprod\wassup

Than I put my Wassup.java file there.
Then I compile to create Wassup.class in that same directory
then I jar to create wassup.jar
then I sign the jar (a step you can leave out for now).
then I post that on my website or run the jar locally.

I usually give my Applet a main method so I can run it as as
application to debug it without the fuss of a browser.

If you use an IDE it creates the package directories for you in
project directories. You organise your related packages into
projects.

Do you need to include the directory info in the jar?

Roedy Green · Sep 21, 2005

I have a book on java 2 somewhere, probably in the attic. Bloody hell i hate
the dark.

You can get something on eBay or in one of those cheap computer
bookstores that specialise in slightly out of date books.

Roedy Green · Sep 21, 2005

Do you need to include the directory info in the jar?

You need at least a main class. Its java name is for example:

com.mindprod.wassup.Wassup.class

In the jar in will have the name:

com/mindprod/wassup/Wassup.class

You don't need an entry for each directory level, just the files.
Jar.exe handles that. You just tell it which classes and resources you
want in there.

When you sign it will add some additional files of the digests and
digital signatures.

Verify you got it right with Winzip or something similar.

Dag Sunde · Sep 21, 2005

Roedy Green said:
You don't post a class without a package. That is only for
experimenting. I suspect signing presumes packages.

Signing does not presume/need packages, but I agree with you.
(One should use them to keep things globally unique)

I suspect "jar" messes up a little when he doesn't use packages,
but gives a full ms-dos path to his .class file

<quote>
c:\j2sdk1.4.2_06\bin\jar cvf c:\applets\Helloserver.jar
c:\applets\Helloserver.class
c:\j2sdk1.4.2_06\bin\jarsigner c:\applets\Helloserver.jar dazkey
c:\j2sdk1.4.2_06\bin\jarsigner -verify -verbose -certs
c:\applets\Helloserver.jar
</quote>

I think the results will be different if he change to "c:\applets"
and try to jar, and sign it from there, the results might be different:
c:\applets> jar cvf helloserver.jar Helloserver.class
c:\applets> jarsigner helloserver.jar dazkey
c:\applets> jarsigner -verify -verbose -certs helloserver.jar

And Darren...

Can you give us the result the last command you run:
"jarsigner -verify -verbose -certs helloserver.jar"

Dag Sunde · Sep 21, 2005

Darren said:
Hi i wrote an applet recently and posted a request here for help in
allowing
it to open a socket. I got some excellent info on creating self signed jar
files that allow me access to functions normally prohibited to java
applets.
Now i've follwoed the instructions but now my heml code has trouble
accessing the jar file.

Hello Darren...

I promised in another thread to sign an applet, and send it to you
so you could test if it worked at all...

I sendt a test-setup with source & a signed applet to your
"devslashnul.net" address, but i suspect that isn't a valid one.

If you mail me your address, I'll send it to you.

getting error on applet again	16	Sep 30, 2005
java applet classpath	5	Apr 19, 2006
Deploy applet with JNLP file load wrong package	2	Jan 20, 2011
Applet deployment problem	16	Feb 25, 2009
java.lang.SecurityException: Prohibited package name: java	9	Jul 17, 2006
reading image files from applet -- newbie question	4	Jul 27, 2005
Lazy applet JAR downloading using JNLP - Part II	7	Aug 17, 2009
Problem when using AJAX to load a Java applet	4	Jun 10, 2008

having trouble using signed java applet

Darren

Roedy Green

Roedy Green

Roedy Green

Roedy Green

Roedy Green

Darren

Darren

Darren

Oliver Wong

Roedy Green

Roedy Green

Roedy Green

Roedy Green

Darren

Darren

Roedy Green

Roedy Green

Dag Sunde

Dag Sunde

Ask a Question

Similar Threads

Members online

Forum statistics

Latest Threads