Hi Folks,
Yes I believe it is, but only by being sneaky.

Extract the metadata from isc4.gdb.
Recreate it owned by a different super user, ie myuser.
Add a sysdba role to the database.
Pump the contents of the old database to the new one.

Recreate your real databases owned by your new superuser.
Add a sysdba role to the database.

Never give out the superuser username.

This seems to work. You can still backup, restore etc.

But the key thing is to keep the superuser username secret.

If anyone knows it, they can add a user with that name to a normal
isc4.gdb and access your data.

Its still not that secure, because people could use a hex editor to
get your master username.

Regards
Ian Newby