JSS 4.3 README
Full binary releases are no longer provided for JSS on ftp.mozilla.org
jss4.jar – is provided because the jss4.jar is signed with a JCE code-signing certificate. You need to build
JSS's matching JNI shared library for your platform.
https://developer.mozilla.org/En/JSS/4_3_ReleaseNotes
https://developer.mozilla.org/jss_build_4.3.html