T ABLE 10.1 Main Permissions At a Glance
J2EE Application Client
Access Local File System
Download resources in
JARs from other Web
Download JREs and
extensions from any
Exiting the JVM and
Access system Clipboard
Also known as signed applications , authenticated applications verify the following properties.
•All JAR files (for jar and nativelib elements) must be signed. A JAR file is considered
signed when all its entries are signed with the same certificate (except of course of stan-
dard files in the META-INF directory).
•To simplify user interaction, only one certificate is used to sign all JAR files mentioned
in a single JNLP file. This means that users are asked for authorization only once.
• If the certificate used to sign JAR files is signed itself, it must be verified against a set of
root certificates, from the major certificate authorities. This set of root certificates usually
comes bundled with the JNLP Client.
Furthermore, JNLP files can be optionally signed; that is, when a copy of the main JNLP file is
included in the main (signed) JAR file with the name “JNLP-INF/APPLICATION.JNLP”, and
the two copies match byte-wise. Then, the JNLP file is considered to be signed. Note that this
feature is only optional, and signing applications as defined above will suffice.
In order to be run in a trusted environment (J2EE Application Client or All-Permission), the
application must be signed as defined above. It must also be explicitly authorized by the user
by means of an authorization window shown just before allowing the potentially dangerous