Applet doesn't work on JRE 7

Question

I have a trouble with loading applet after recent security updates in JRE 7. Applet works fine on JRE 6, but on 7 I get following error messages:

Popup window with error:

ExitException[ 3]com.sun.deploy.net.FailedDownloadException: Unable to load resource: http://URL_TO_SERVER:9081/Application/applet/lib/ExternalLibrary.jar
    at sun.plugin2.applet.JNLP2Manager.downloadResources(Unknown Source)
    at sun.plugin2.applet.JNLP2Manager.prepareLaunchFile(Unknown Source)
    at sun.plugin2.applet.JNLP2Manager.loadJarFiles(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

And in Java console I can see same error as above, but also some extra information:

java.lang.SecurityException: invalid SHA1 signature file digest for com/ibm/api/admin/DirectoryConfigurationSunOne.class
    at sun.security.util.SignatureFileVerifier.verifySection(Unknown Source)
    at sun.security.util.SignatureFileVerifier.processImpl(Unknown Source)



java.io.IOException: invalid SHA1 signature file digest for com/ibm/api/admin/DirectoryConfigurationSunOne.class
    at com.sun.deploy.cache.CacheEntry$10.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.deploy.cache.CacheEntry.writeFileToDisk(Unknown Source)

How to solve this problem? Thanks.

Answer 1

JAR file was signed twice, it was a problem.