There is nice way how to sign your jars using Thawte Freemail Certificate. I think it is fine for code given out for free.
<signjar keystore="your_keystore.p12"
storetype="pkcs12"
alias="your_alias"
storepass="secret">
<fileset dir="${client.deploy.dir}/lib">
<include name="**/*" />
</fileset>
</signjar>
Step by step guide:
- Ask Thawte for your certificate.
- Download it to your Firefox.
- Choose Edit/Preferences/Encryption/View Certificates/<select>/Backup (use PKCS12)
- If you don't know your alias use this to list it:
keytool -list -storetype pkcs12 -keystore your_keystore.p12
P.