[Security / applet ] signed applet with permission failed - Java

Iwant an applet who can read files but not write:

test 1 :
not signed applet with grant permissions in .java.policy : ok

test 2 :
a signed applet with the same permissions in .java.policy : no ok , i
can write files

Itried several tests (define a keystore with policytool and so on) but
it failed.

My question : with signed applet, is-it possible to add permissions or
signed applet => all permissions ?


Thanks