A copy-resistant read-only digital optical disc having encrypted digital data. The copy-resistant read-only digital optical disc includes a digital work, a variable user data format encoding said digital work after encryption with a variable software algorithm, an implementation of said variable software algorithm, and an implementation of said variable user data format encoded in a default format. The encrypted digital data is read on an adaptable digital optical disc player, which is adaptable to a user data format described on said copy-resistant read-only digital optical disc made in accordance with this invention. A copy-resistant read-only digital optical disc made in accordance with this invention will provide necessary user data format information on the disc in a default format, which is always accessible by an adaptable player.