Run Keygen.Jar
Download the KeyGen for your program. Normally, pirated programs come zipped with a KeyGen that will work. Install the program to your computer, but.
I created a JAR file like this:
I ran this JAR file by double clicking on it (it didn't work). So I ran it from the DOS prompt like this:
It raised 'Failed to load main class' exceptions. So I extracted this JAR file:
and I ran the class file:
It worked well. I do not know why the JAR file did not work. Please tell me the steps to run the JAR file
11 Answers
You need to specify a Main-Class in the jar file manifest.
Oracle's tutorial contains a complete demonstration, but here's another one from scratch. You need two files:
Test.java:
manifest.mf:
Note that the text file must end with a new line or carriage return.The last line will not be parsed properly if it does not end with anew line or carriage return.
Then run:
Output:
Before run the jar check Main-Class: classname is available or not in MANIFEST.MF file. MANIFEST.MF is present in jar.
You have to add a manifest to the jar, which tells the java runtime what the main class is.Create a file 'Manifest.mf' with the following content:
Change 'your.programs.MainClass' to your actual main class. Now put the file into the Jar-file, in a subfolder named 'META-INF'. You can use any ZIP-utility for that.
A very simple approach to create .class, .jar file.
Executing the jar file. No need to worry too much about manifest file. Make it simple and elgant.
Java sample Hello World Program
Compiling the class file
Creating the jar file
or
Running the jar file
Or
Run Keygen On Windows
If you don`t want to create a manifest just to run the jar file, you can reference the main-class directly from the command line when you run the jar file.
This sets the which main-class to run in the jar file.
If you don't want to deal with those details, you can also use the export jar assistants from Eclipse or NetBeans.
Eclipse Runnable JAR File
Create a Java Project – RunnableJAR
- If any jar files are used then add them to project build path.
- Select the class having main() while creating Runnable Jar file.
Main Class
Run Jar file using java program (cmd) by supplying arguments and get the output and display in eclipse console.
In Eclipse to find Short cuts:
Help ► Help Contents ► Java development user guide ► References ► Menus and Actions
I have this folder structure:
D:JavaProjectsOlivePressAppcomlyndaolivepressMain.class D:JavaProjectsOlivePressAppcomlyndaolivepresspressOlivePress.class D:JavaProjectsOlivePressAppcomlyndaolivepressolivesKalamata.class D:JavaProjectsOlivePressAppcomlyndaolivepressolivesLigurian.class D:JavaProjectsOlivePressAppcomlyndaolivepressolivesOlive.class
Main.class is in package com.lynda.olivepress
There are two other packages:
Cannot Run Keygen
com.lynda.olivepress.press
com.lynda.olivepress.olive
1) Create a file named 'Manifest.txt' with Two Lines, First with Main-Class and a Second Empty Line.
D:JavaProjectsOlivePressApp Manifest.txt
2) Create JAR with Manifest and Main-Class Entry Point
D:JavaProjectsOlivePressApp>jar cfm OlivePressApp.jar Manifest.txt com/lynda/olivepress/Main.class com/lynda/olivepress/*
3) Run JAR
java -jar OlivePressApp.jar
Note: com/lynda/olivepress/* means including the other two packages mentioned above, before point 1)
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To run jar, first u have to create
executable jar
then
java -jar xyz.jar
command will work
Related to this question, can / should I use jar signing to create a tamper proof jar with information embedded for run-time enforcement of the number of users allowed to use the application? My idea is this:
- Create jar with single class containing static field holding the right number of users
- Sign the jar and place in Grails war lib folder so on classpath
- (Assumption, is this correct?) I can access the the static field in the class in the signed jar file from my grails application safely knowing that the jar has not been tampered with (otherwise an exception will be thrown), and also without any extra work required like 'accepting' the signature.
Is my step 3 assumption correct? Is this a good approach for what I am trying to do? If not, what is standard practice?
Thanks!
2 Answers
It's only 'tamper proof' if the user has to run it in some environment that insists that the signature is present and functional. If you hand a jar to an ordinary person who can run it in an ordinary JVM (not as an applet, not as a webstart), they are free to remove the signature altogether. If you want to try to stop this, you'd have to write code to call Class.getSigners and explode if you didn't see yourself. So, they'd need to fire up asm to write that check out of existence, and they'd be good to go.
Java code signing allows some container to verify that a jar file maintains integrity from its source. It does not give you a means of creating a tamper-proof package.
Simple JAR signing won't work. JAR signing is all about the client trusting your JAR file. It doesn't prevent the client from creating a new JAR from your JAR's contents (with tweaks) and running it as an unsigned JAR.
Classes in your JAR could attempt to check that they are loaded from a suitably signed JAR, but any such class could be tweaked to disable the check. So that is a speed-bump for a determined attacker .. but certainly not an indefeasible solution.
The normal way to implement limits on simultaneous users is to implement a separate license manager / license key system; e.g. FlexLM. (And of course, that too can be defeated by tweaking your classes to skip the license check.)
The bottom line is that any license management scheme for code running on machines controlled by your client can be defeated.