Content guard system for copy protection of recordable media

A computer-implemented method for enabling data to be copied one time only onto a media device, comprising the acts of:

• writing at least one media identification and at least one one-way key management key block onto the media device, at least the media identification being written in a read-only area;
• deriving a media key from the media block and combining the media key with the media identification to render a content key;
• establishing an exchange key between a recorder and a sender having access to the data;
• modifying the exchange key using at least one special number representing a copy command to render a modified exchange key;
• encrypting the modified exchange key using the content key to render an encrypted modified exchange key;
• and
• using the encrypted modified exchange key or a hash thereof, encrypting the data for copying the encrypted data once only to a copy media device.

A recorder computer program storage device including a program of instructions for writing data to a digital disk, each disk including a respective media identification written to an ID location on the disk, the disks also including a common one-way key management media key block, the program of instructions including structure comprising:

• computer readable code means for, for each disk, determining a media key from the common one-way key management media key block;
• computer readable code means for combining the media key with the media identification to render a content key;
• and
• computer readable code means for encrypting the data using the content key for recordation of the encrypted data on the disk.

A user computer program storage device accessible by a player-recorder establishing a player and a recorder, the user computer program storage device including:

• computer readable code means for sending encrypted data from a data storage medium to the player;
• computer readable code means for reading media identification and a media key block on the data storage medium;
• computer readable code means for determining a media key using the media key block;
• computer readable code means for determining a content key using the media key and the media identification;
• and
• computer readable code means for decrypting data on the data storage medium using the content key to facilitate the player playing video and/or audio represented by the data.