Dear Klaus,
In versions <= 6.4.4,
boot: knoppix secure adriane
will leave knoppix in the sudoers file, etc., and means that putting
"secure" in every APPEND in the bootloader config file can be effectively
overridden at the boot prompt with bootparam "adriane".
The cause can be seen in lines 744-767: There is no secure adriane mode.
Best regards,
Andrew