Protection of data on media recording disks

1. A method for protecting access to content recorded on a media recording disk (DVD), the method comprising:

providing a disk security chip on the DVD, the disk security chip managing access to the content of the DVD;

providing a corresponding player security chip in a DVD player which is operative to play the DVD, the player security chip managing use of a data stream received from the DVD, the disk security chip being in wireless communication with the player security chip;

providing the disk security chip with a disk key;

the player security chip sending a random number R to the disk security chip, the random number R being different each time the DVD is played;

the disk security chip sending the player security chip an encrypted concatenation of a hash function of R, called h(R), and the content key, encrypted with the disk key;

the player security chip decrypting the concatenation, and computing h(R) and comparing with the h(R) sent by the disk security chip;

the player security chip verifying R to be correct, thereby certifying that the disk chip really knows the player key;

the player security chip obtaining the content key from the concatenation; and

the player security chip using the content key to decrypt control words that are located within entitlement control messages (ECMs) in the DVD.

2. The method according to claim 1 and wherein the disk key is not known to a disk manufacturer.

3. A system for protecting access to content recorded on a media recording disk (DVD), the system comprising:

a disk security chip on the DVD, the disk security chip managing access to the content of the DVD, the disk security chip comprising a disk key;

a corresponding player security chip in a DVD player which is operative to play the DVD, the player security chip managing use of a data stream received from the DVD, the disk security chip being in wireless communication with the player security chip, the player security chip being operative to produce a random number R for sending from the player security chip to the disk security chip, the random number R being different each time the DVD is played,

wherein the disk security chip sends the player security chip an encrypted concatenation of a hash function of R, called h(R), and the content key, encrypted with the disk key, and the player security chip is operative to perform the following steps:

decrypt the concatenation, and compute h(R) and compare the computed h(R) with the h(R) sent by the disk security chip;

verify R to be correct, thereby certifying that the disk chip really knows the player key;

obtain the content key from the concatenation; and

use the content key to decrypt control words that are located within entitlement control messages (ECMs) in the DVD.

4. The system according to claim 3 and wherein the disk key is not known to a disk manufacturer.

5. A system for protecting access to content recorded on a media recording disk (DVD), the system comprising:

means for providing a disk security chip on the DVD, the disk security chip managing access to the content of the DVD;

means for providing a corresponding player security chip in a DVD player which is operative to play the DVD, the player security chip managing use of a data stream received from the DVD, the disk security chip being in wireless communication with the player security chip;

means for providing the disk security chip with a disk key;

means for sending a random number R from the player security chip to the disk security chip, the random number R being different each time the DVD is played;

means for sending an encrypted concatenation of a hash function of R, called h(R), and the content key, encrypted with the disk key from the disk security chip to the player security chip;

means for decrypting the concatenation by the player security chip, and computing h(R) and comparing with the h(R) sent by the disk security chip;

means for verifying R to be correct at the player security chip, thereby certifying that the disk chip really knows the player key;

means for the obtaining, by the player security chip, the content key from the concatenation; and

means for using the content key at the player security chip to decrypt control words that are located within entitlement control messages (ECMs) in the DVD.