Java 7.51 – Applets must be signed

With the new Java update 7.51 all applets must follow new guidelines:

  1. All code for Applets and Web Start applications must be signed
  2. Permissions attribute in the manifest must be set, no default

Read more here

What this means is any applet that currently exists that is not signed, has an expired certificate, or doesn’t have the permissions attribute will no longer work. As a side job I make sure works, and it was affected by this so here’s how to fix it.

Quick Answer:

  1. Buy a code signing certificate
  2. Resign your applet
  3. Done

Here’s how:

  1. Create a txt file for the manifest additions. Here are the contents:
    Permissions: all-permissions
    Application-Name: MyAppletName
  2. Extract you jar:
    > mkdir jarname
    > mv jarname.jar jarname
    > cd jarname
    > jar xf jarname.jar
  3. Remove the META from the extract
    > rm -r META-INF/
  4. Rejar the applet and include the required manifest additions
    > jar cfm jarname.jar ../manifestAdditions *
  5. Sign the jar. Here’s my posts to do the signing:
    > Create a Java keystore from a p12 file
    > Finding an imported certificate’s alias in a java keystore
    > How to sign a jar


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