Slick2D applet, signing jars?

[GhostID]

Okay so I figured out how to make Slick2D applets, but when I come to add images or sounds to it, it stops working... From looking around and opening up other slick2d applets, I've noticed that they have 3 files in their meta-inf.

.MF
.DSA
.SF

My meta-inf only has the .MF file, which looks like this:

"Manifest-Version: 1.0"

That's it.

With more research, I found out that there are programs to sign jars. The thing is, they cost money.

SOO here's my final question,
is there a free way to sign my jars..? What programs can be used (or is it just an option) ?

[GabrielBailey74]

Have a google for: "RSPS Jar Signer" ^_^

[joen]

You can use the "jarsigner" tool that comes with the jdk, with either a free self signed certificate, or a certificate from a security company like Thawte or Verisign.