STUPID ME 😉

Re-checking the installation of the JCE files brought me on the right track.

Executing the hadoop-command on the shell was using "old" Java6 and I installed the JCE files just for Java7, since I configured in CM JAVA_HOME to use Java7.

A simple "export JAVA_HOME=/usr/lib/jvm/java-7-oracle/jre" before executing "hadoop dfs ..." on the shell solved this issue.