Hi,
in fact that is possible!!!
I find the solution this week-end!!!
I follow the instructions on this webpage :
http://wiki.jboss.org/wiki/Wiki.jsp?page=EncryptingDataSourcePasswordsIndeed,
I delete user and password in the files adobe-ds.xml and oracle-ds.xml
I replace that by security-domain which refers to the file login-config.xml.
It is in this file there is the user and the password. But the password is encrypted by the command :
java -cp lib/jboss-jmx.jar:lib/jboss-common.jar:server/default/deploy/jboss-jca.sar:server/default/lib/jbosssx.jar org.jboss.resource.security.SecureIdentityLoginModule password
So it works well!!! :)
Have a good day!!!