MXPA06000910A - Secure pre-recorded digital medium - Google Patents

Abstract

A secure pre-recorded medium (110) and a method for descrambling encrypted content (114) thereon. When a player (120) wants to access the content, a secure processor (111) on the medium verifies (202) that the player has not been revoked, preferably by comparing an identity of the player with identities in a revocation list (113), after which a mutual authentication is performed (204). The secure processor then verifies (205) that the player has the rights to access the content and provides (206, 207) the player with the key necessary to descramble the content, whereafter the player descrambles (208) the content.

Description

SECURE PRE-ENGRAVED DIGITAL MEDIA The present invention relates in general to digital recording media and in particular to security for pre-recorded digital media. The proliferation of digital recording media has allowed many people to enjoy the content, such as movies and music, without, at least in theory, a deterioration in quality over time. Unfortunately, it has also offered possibilities for piracy, since pure digital content can be copied very easily an unlimited number of times. To counter this, many different solutions have been proposed as to how to protect digital content. Versatile Digital Discs (DVDs) that make up a large part of the media sold, for example, use static storage. To prevent illegal copying, digital content on DVDs is encoded using the Content Decoding System (CSS) algorithm. The key used for coding is dedicated and a corresponding key, used for decoding, is common to each player of a manufacturer. Players for the most recent pre-recorded media, such as those protected by the Biu-ray Disc Copy Protection System (BD-CPS) and Content Protection for Pre-recorded Media (CPPM) each has a unique set of keys. The protection is based on broadcasting techniques, such as for example the Flat-Naor scheme. There have also been attempts to transform a static medium into a dynamic one by adding a processor to the recording medium. Japanese patent application 10-242555 describes a CD-ROM with a built-in secure processor that communicates with the player. The processor transmits a password to the player, and the password allows decryption of the content. This solution, however, is susceptible to attacks on reproduction. Another Japanese patent application, 10-050713, discloses a system using a recording medium with an integrated IC circuit, which retains the decryption key for the content. The integrated circuit IC passes the key to the guest only with successful guest authentication, and adds a counter to limit the number of times the key can be transferred. This solution does not prevent, however, that a pirate creates counterfeit titles. Also, if a pirate manipulates to build a fake player, he can use techniques that expose the decoding key. Therefore it can be seen that there is a need for a flexible solution that overcomes the problems of the technique above and increases the security of pre-recorded digital media. The present invention provides such a solution. In a first aspect, the invention is directed to a method of decoding by a content encrypted in the player on a secure medium comprising a secure processor. The secure processor verifies that the player has not been revoked and provides the player with the necessary key to decode the content and the player decodes the content. It is preferred that the secure processor verify that the player has the rights to access the content. It is advantageous that the content is divided into chapters and that the secure processor verifies that the player has the rights to access the content for each chapter. It is advantageous for the secure processor to have access to a revocation list and to verify that the player has not been revoked by comparing a player identity with identities in the revocation list. It is further preferred that the secure processor and the player mutually authenticate each other. It is further preferred that, in order to provide the player with the necessary key, the player reads an encrypted version of the decoding key from a content memory on the medium and sends it to the secure processor, which decrypts the key and sends it to the player. .

In a second aspect, the invention is directed to a method for decrypting encrypted content on a secure medium comprising a secure processor. A player authenticates the secure processor, rees the necessary key to decode the content, and decodes the content. It is preferred that, in order to ree the key necessary to decode the content, the player reads an encrypted version of the decoding key of a content memory on the medium, sends the encrypted decoding key to the secure processor and rees the key from the secure processor. of decoding. In a third aspect, the invention is directed to a method for providing a player with encrypted content on a secure medium comprising a secure processor. The secure processor verifies that the player has not been revoked, authenticates the player and provides the player with the necessary key to decode the content. It is preferred that the secure medium verify that the player has the rights to access the content. It is advantageous that the content is divided into chapters and that the secure processor verifies that the player has the rights to access the content for each chapter. It is also preferred that the secure processor have access to a revocation list and that the secured processor verify that the player has not been revoked by comparing a identity of the player with existing identities in the revocation list. It is further preferred that, in order to provide the player with the necessary key to decode the content, the secure processor rees an encrypted decoding key from the player, decrypts the encrypted decoding key and sends the decoding key to the player. It is further preferred that the secure processor encrypts the key before providing it to the player. In a fourth aspect, the invention is directed to a means for use by a player. The medium comprises a content memory that stores encrypted content and a secure processor, and stores a revocation list. It is preferred that the secure processor be adapted to verify that the player has not been revoked. It is advantageous for the secure processor to have access to a revocation list and to verify that the player has not been revoked by comparing a player identity with existing identities in the revocation list. It is also preferred that the secure processor be adapted to authenticate the player. It is further preferred that the secure processor be adapted to verify that the player has the rights to access the content.

It is advantageous that the content is divided into chapters and that the secure processor verifies that the player has the rights to access the content at least once for each chapter. It is further preferred that the secure processor be adapted to provide the player with the necessary key to decode the content. It is advantageous that, in order to provide the player with the necessary key to decode the content, the secure processor rees an encrypted decoding key from the player, decrypts the encrypted decoding key and sends the decoding key to the player. It is further preferred that the secure processor is a radio frequency (RF) integrated circuit. The preferred aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 illustrates the interaction of a secure pre-recorded medium and a corresponding player according to the invention; Figure 2 illustrates the method of accessing the medium according to the invention; and Figure 3 illustrates the provision of the necessary decoding key.

PREFERRED MODE OF THE INVENTION Figure 1 illustrates the interaction of a secure pre-recorded medium 110 and a corresponding reproducer 120 according to the invention. The medium 1 10 stores encrypted content 1 14 in a content memory 112 that is freely accessible by the player 120. The information, such as the decryption keys, necessary to decrypt the code 1 14 is stored in a secure processor 111. A person skilled in the art will appreciate that the secure processor 111 may have inherent storage capacity (not shown), but that it may also use the storage capacity of the medium, such as the content memory 112 and secure storage using an internal key. to the secure processor. The player 120 comprises an interface module 121 that handles communication with both the secure processor 111 and the content memory 1 12 of the medium 1 10, that is, is able to read content 114 of the content memory 112 and communicate with each other. with the 11 I n secure processor. The interface module may be capable of optical interaction, radio interaction, or both optical and radio interactions, for example to interact optically with the content memory 112 and by radio with the secure processor 111. The player 120 further comprises an authenticator 122, a master manager 123 and a decoder 124, which will be described additionally in the following. In a particularly preferred embodiment, the authenticator 122 and the main administrator 123 are comprised in a central processing unit 126 (CPU), and the decoder 124 is an Advanced Encryption Standard decoding integrated circuit (AES for its acronym in English). The interface module 121 may also communicate with these three units 122, 123 and 124. The player 120 may also comprise a content receiver 125 which, although not part of the invention as such, will be discussed briefly hereinafter. Figure 2 illustrates the method of access to the medium according to the invention. When the medium 110 is to be read by the player 120, usually when the user has inserted the medium into the player and has pressed "play" or a similar key, the method starts at step 201"START". In step 202"Revocation?", The secure processor 111 checks whether the player 120 has been revoked. This is done for example by comparing the identity of the player against a revocation list 113 which is in the memory of the secure processor. If the player has been revoked, "S", then the secure processor 111 aborts the method, step 203"END" and does not accept to communicate with the player 120. This means that the authenticated medium can only be reproduced in players that have not been revoked.

However, if the player has not been revoked, the method continues. The authenticator 122 of the player 120 and the secure processor 111 then mutually authenticate each other in the step 204"Authentication". If the authenticator 122 can not authenticate the medium 11, "Not successful", then the player 120 aborts the method, stops at step 203, and does not accept to play the medium 1 10. Thus, the player only reproduces media from authenticated providers, which to some extent counterattacks organized piracy. If, on the other hand, the secure processor 111 can not authenticate the player 120, "Not successful", then it aborts the method, proceeds to step 203, and does not accept to communicate with the player 120. Thus, it is assured to a certain extent that the authenticated medium is only reproduced in authenticated players. With successful and mutual authentication, "Successful", the method moves to stage 205"Rights?". The secure processor 11 1 verifies that the player 120 has the necessary rights to reproduce the content 114. In many cases, this is automatically true (in which case this step is superfluous), but there are cases in which additional restrictions are desired - for example to certain players only, to certain parts of the content 114 only, limitations as to the number of times a medium can be reproduced -. He The secure processor 111 can verify for example that it has the identity of the player 120 stored in its memory. If the secure processor 11 1 finds that the player does not have the appropriate rights, then it aborts the method, proceeds to step 203, and does not accept to communicate with the player 120. However, if the player 120 has the requisite rights, then the method continues in step 206. Once it has been decided that the medium 110 can supply the content 14 to the player 120, the secure processor 1 1 1 sends the information necessary to decrypt the content 14 to the main administrator via the module 121 of interface; stage 206"Clave secreta a admn ppal". The information may be for example the type of decryption key needed or the decryption key itself, although this is by no means a complete enumeration. The information may correspond to the entire content 14 or a part of the content 14, such as the section that is, or will be, reproduced. The transfer of information is preferably ensured by the use of encryption. In step 207"Calculate key", the main administrator 123 uses the received information to calculate the decryption key and passes it to the decoder 124. In step 208"Decoding content", the interface module 121 reads the encrypted content 114 of the content memory 112 and transmits it to the decoder 124, continuing until it is released from content, for which it has a password of decoded. The decoder 124 decrypts the content, using the decryption key received from the main administrator 123, and transmits the decrypted content to a content receiver 125, for example a digital bus, using the content. In stage 209"More content?" it checks if there is more content to play. If this is not the case, "N", then the method stops at step 203. However, if there is more "S" content, the method continues at step 205"Rights?" to verify that the player has the requisite rights for the upcoming content, as described above. In an alternative embodiment, the method continues directly in step 206"secret key to admn ppal" without verification of the rights. In both modalities, this is done at an appropriate time so that the decoder 124 is always in possession of the key or keys it needs to decipher the content, with the proviso that, of course, the player has the requisite rights. In a particularly preferred embodiment, the secure processor 1 of the medium 110 is a radio frequency (RF) integrated circuit that does not need a battery, does not need to be in physical contact with the player 120, and can be read even if it is covered. for example for reasonable amounts of dirt. The interface module 121 comprises a radio frequency interface that emits a low frequency radio wave field to supply power to the secure processor 111 and it also comprises a traditional optical reader for reading the content 114 stored in the content memory 12. Further, in the particularly preferred embodiment, the content memory 112 stores encrypted content 14 organized into chapters (such as songs and scenes, for example), where each chapter i is encoded with AES using the key K ,. The secure processor 1 1 1 stores a unique pair of public / private keys signed by a first certification authority A, the public key of a second certification authority B, the revocation list 113, and a title key TK. The authenticator 122 stores a unique pair of public / private keys signed by the second certification authority B, and the public key of the first certification authority A. Still in the particularly preferred embodiment, in step 202"Revocation?" the secure processor 11 1 verifies that the certificate of the public key of the authenticator 122 is not found in the revocation list 113. The step 204"Authentication" is performed using the respective public / private key pairs. Secure processor 111 and authenticator 122 establish a secure authenticated channel using, for example, an exchange of authenticated Diffie-Hellman keys that creates a shared session Ksess key. As for stage 205"Rights?", The property of the medium 110 confers permanent rights. Figure 3 illustrates the provision of the necessary decoding key. In stage 206, when you are initiating a new chapter i, the main load manager 123, step 302, the first encrypted decoding key Eki and pass it, step 304, to the processor 1 1 1 sure to decrypt the decoding key using the title key TK, step 306 , and re-encrypting with AES using the session key KSess, step 308. The secure processor 1 1 1 then passes the re-encrypted decoding key to the main administrator 123, step 310, which receives the decode key, step 312 , decrypts it with AES using the KseSs session key. step 314, and feed the decoded decryption key to the decoder 124, step 316. It will be understood that the present invention has been described purely by way of example, and modifications of details may be made without departing from the scope of the invention. Each aspect described in the description and (where appropriate) the claims and the drawings may be provided independently or in any appropriate combination. The aspects described as implemented in hardware can also be implemented in software, and vice versa. The connections can, when applicable, be implemented as wireless connections or with electrical installation, not necessarily direct or dedicated connections. The reference numbers appearing in the claims are by way of illustration only and will not have a limiting effect on the scope of the claims.

Claims (23)

1. CLAIMS 1. Method for decoding an encrypted content by a player on a secure medium comprising a secure processor, the method is characterized in that it comprises the steps of: providing, by the secure processor, the player with the necessary key to decode the content; verify, by the secure processor, that the player has not been revoked; and decoding, by the player, the content.
2. 2. Method according to claim 1, further characterized by the step of verifying, by the secure processor, that the player has the rights to access the content.
3. 3. Method according to any of claims 1 to 2, further characterized by the step of mutually authenticating the secure processor and the player among themselves.
4. 4, Method according to claim 1, further characterized in that the secure processor has access to a revocation list and because the step of verifying that the player has not been revoked is done by comparing a player identity with identities that are in the revocation list .
5. 5. Method according to claim 2, further characterized in that the content is divided into chapters and because the step of verifying that the player has the rights to access the content is made for each chapter.
6. 6. Method according to any of claims 1 to 5, further characterized in that the step of providing the player with the necessary key to decode the content comprises the steps of: reading, by the player, an encrypted version of the decoding key of a memory of content about the medium; send, by the player, the encrypted decoding key to the secure processor; deciphering, by the secure processor, the encrypted decoding key; and send, by the secure processor, the decoding key to the player.
7. 7. Method for decoding encrypted content on a secure medium comprising a secure processor, the method is characterized in that it comprises the steps, in a player, of: authenticating the secure processor; receive, from the secure medium, the necessary code to decode the content; and decode the content.
8. 8. The method according to claim 7, further characterized in that the step of receiving the key necessary to decode the content from the secure means comprises the steps of: reading an encrypted version of the decoding key of a content memory on the medium; send the encrypted decoding key to the secure processor; receive the decoding key from the secure processor.
9. 9. Method for providing encrypted content on a secure media to a player, the secure means comprises a secure processor, the method is characterized in that it comprises, in the secure processor, the steps of: verifying that the player has not been revoked; authenticate the player; and provide the player with the necessary key to decode the content.
10. 10. Method according to claim 9, further characterized by the step of verifying that the player has the rights to access the content.
11. 11. Method according to claim 9, further characterized in that the secure processor has access to a revocation list and because the step of verifying that the player has not been revoked is done by comparing a player identity with identities that are in the revocation list.
12. 12. Method according to claim 10, further characterized in that the content is divided into chapters and because the step of verifying that the player has the rights to access the content is done for each chapter.
13. 13. Method according to any of claims 9 to 12, further characterized in that the step of providing the player with the necessary key to decode the content comprises the steps of: receiving from the player an encrypted decoding key; decrypt the encrypted decoding key; and send the encrypted decoding key to the player.
14. 14. Method according to claim 9, further characterized in that the secure processor encrypts the key before providing it to the player.
15. 15. Medium to be used by a player, the medium comprises a content memory that stores encrypted content, the means is characterized in that it additionally comprises a secure processor and stores a revocation list.
16. 16. Medium according to claim 15, further characterized in that the secure processor is adapted to verify that the player has not been revoked.
17. 17. Medium according to claim 15, further characterized in that the secure processor is adapted to authenticate the player.
18. 18. Medium according to claim 15, further characterized in that the secure processor is adapted to verify that the player has the rights to access the content.
19. 19. Medium according to claim 15, further characterized in that the secure processor is adapted to provide the player with the necessary key to decode the content.
20. 20. Medium according to claim 16, further characterized in that the secure processor has access to the revocation list and because it is adapted to verify that the player has not been revoked by comparing a player identity with identities that are in the revocation list.
21. 21. Medium according to claim 18, further characterized in that the content is divided into chapters and because the secure processor is adapted to verify that the player has the rights to access the content at least once for each chapter.
22. 22. Medium according to claim 19, further characterized in that the secure processor, in order to provide the player with the necessary key to decode the content, is adapted to: receive an encrypted decoding key of the player; decrypt the encrypted decoding key; and send the encrypted decoding key to the player.
23. 23. Medium according to claim 15, further characterized in that the secure processor is a radio frequency (RF) integrated circuit.