Is it possible to re-sign a Java applet with a newer certificate?

Question

I have a signed Java applet, and the certificate just expired. I have a new certificate, but I'm not sure that I can find the original, unsigned applet jar file. Is there any way that I can take the signed jar and replace the old certificate with a new one? Thanks.

Answer 1

You can't wrap it.

However, you should be able to simply re-sign the JAR with a different certificate. Signing a JAR doesn't encrypt it in anyway. It just adds stuff to the manifest section.

This is not a security issue. The re-signed certificate is different to the original one, the end-user has to accept it all over again. (I don't think you can avoid that ... because it would be a security issue!)

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Anyway, the simple approach is to just try re-signing the signed applet JAR, and see whether it works, and how it behaves when you try to run it as a user.