Disclosed are techniques and systems for manufacturing an optical disc having a stochastic (i.e., non-deterministic) anti-piracy feature in the form of a multi-spiral structure, and for verifying the feature on the optical disc to authenticate the disc for playback. The multi-spiral structure may be comprised of multiple partially interleaved, and partially overlapping, spiral data tracks formed in a designated area of the optical disc. A process of forming the multi-spiral structure may include forming, in the designated area, a first spiral data track with first track pitch and a second spiral data track with second track pitch that is different than the first track pitch. The multi-spiral structure may be analyzed to determine verification parameters for verifying the multi-spiral structure, and those verification parameters may be encrypted so that they may be subsequently decrypted and used to verify the multi-spiral structure on a disc reading device.

A playback device includes a port configured to receive content from an external memory device, a device memory residing in the device, and a controller programmed to execute instructions that cause the controller to read a read data pattern from the defined region in the external memory device and determine if the read data pattern correlates to an expected data pattern to a predetermined level, wherein the expected data pattern is derived at least in part from a defect map of the defined region.