Device-independent management of cryptographic information

(12) Patent Specification do) SE 534 641 C2

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Sweden (21) Patent application number: 0950201-4 (45) Patent granted: 2011-11-01 (41) Application generally available: 31 March 2009 (22) Patent application submitted: 2007-05-03 (24) Maturity date: 2007- 05-03 (62) Stock application number: 0701065-5 (83) Deposit of microorganism: - (30) Priority information: 2006-05-03 US 11/381486 (51) International class:

G06F 21/22 (2006.01)

H04L 9/08 (2006.01)

<td>(73) Patent holders:</td><td>APPLE INC., M / S 3-PAT, 1 Infinite Loop, CA 95014 Cupertino US</td>

<td>(72) Inventor:</td><td>Augustin J Farrugia, Cupertino US Gianpaolo Fasoli, Palo Alto US Jean-Francois Riendeau, Cupertino US</td>

<td>(74) Agents:</td><td>Hynell Patenttjänst AB, Box 138, 683 23 HAGFORS SE</td>

<td>(54) Name:</td><td>Device-independent processing of encrypted information</td>

<td>(56) Publications cited:</td><td>US 20050102513 Al</td>

(47) Summary:

Some embodiments provide an account-based DRM system for distributing information. The system includes a number of units associated with a particular account. The system also includes a set of DRM computers, which receive a request for access to a particular set of information on the devices associated with the particular account. The set of DRM computers then generates a number of keys for the devices, whereby each individual key to each individual device allows the particular device to access the particular amount of data on the particular device. The set of DRM computers in some embodiments transmits the particular amount of data and the generated keys through a network to the devices associated with the particular account. The network is a LAN, a WAN or a network of networks, such as the Internet. In some of these embodiments, the set of DRM computers transmits the amount of data and keys to a device (for example, a computer), which is utilized to distribute the data amount and key (s) to the other devices associated with the account. In some embodiments, the set of DRM computers individually encrypts each key in a format used during its transport to the associated device and during use in that device.

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SUMMARY OF THE INVENTION

Some embodiments provide an account-based DRM system for distributing information. The system includes a number of units associated with a particular account. The system also includes a set of DRM computers, which receive a request for access to a particular set of information on the devices associated with the particular account. The set of DRM computers then generates a number of keys for the devices, with each individual key for each individual device allowing the particular device to access the particular amount of data on the particular device. The set of DRM computers in some embodiments transmits the particular amount of data and the generated keys through a network to the devices associated with the particular account. The network is a LAN, a WAN or a network of networks, such as the Internet. In some of these embodiments, the set of DRM computers transmits the amount of data and keys to a device (for example, a computer), which is utilized to distribute the data amount and key (s) to the other devices associated with the account. In some embodiments, the set of DRM computers individually encrypts each key in a format used during its transport to the associated device and during use in that device.

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DEVICE PROCESSING OF Cryptographed Information

TECHNICAL FIELD

The invention relates to device independent processing of encrypted information.

BACKGROUND OF THE ART

The protection of digital data transmitted between computers over a network is fundamentally important for many companies today. Companies are trying to achieve this protection by implementing some form of Digital Rights Management (DRM) procedure. The DRM method often involves encrypting the information (eg, encrypting the binary form of the information) to limit its use to the persons who have been authorized to use it.

Encryption is the traditional method of protecting data during transmission in a network. In its typical application, encryption protects communications between two parties with mutual trust from theft by attacking the data flow during transmission. For many digital file transfer applications today (e.g. for transmitting audio or video information), however, the paradigm has shifted, since a party receiving the information (i.e., the "receiving party") may attempt to break the DRM encryption as the party providing the information (i.e., the "sending party") has applied to the information. Moreover, with the spread of network attacks, a third party can gain access to the receiving party's computer and thus to the protected information.

In many DRM systems today, the weakest link in security is not the encrypted data flow but rather the processing and handling of the encryption key. For example, one of the more successful DRM systems, which distribute music online, requires the receiving party's computer to store the unencrypted key for each piece of encrypted music in the "Key Bag", which is encrypted.

This solution has two disadvantages. First, by encrypting the Keybag instead of the keys in the Keybag, this procedure exposes the keys to a potential attack at different times. Each time the receiving party's computer stores a new key for an amount of information, for example, the computer must decrypt the entire

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The key bag, add the new key to the key bag and then re-encrypt the key bag. Similarly, in order to play a piece, the receiving party's computer must decrypt the entire Key Case, find the key for the piece, and decrypt the piece using this key. In each of these situations, all the keys are exposed to a potential attacker when the Keybag is decrypted.

Secondly, this previously known DRM method allows different devices to utilize different formats for their key bags. It allows, for example, the receiving party's computer to use a different format for the Key Case than a music player to which the computer downloads its music. The use of different formats for the Key Case for different devices also exposes the keys for decrypting the information transmitted between the devices. For example, when the receiving party synchronizes the music player's music library with the computer, the computer must decrypt its Key Case and transfer the synchronized data set and its associated keys to the music player. The music player then stores the received amount of data in a storage device and stores the received keys in the player's special format in the player's key bag. During this transfer, all the keys are exposed to a possible attacker.

Therefore, there is a need in this technology area of ​​a DRM system, which minimizes the exposure of encryption keys at different stages of the DRM process. Such a system should minimize exposure during the local storage of the encryption keys in the devices that use such keys to decrypt and access information. This system should also minimize the encryption key exposure while the encrypted information is read by a receiving device. Furthermore, this system should minimize the exposure of the encryption keys while the receiving device transmits information between two devices.

SUMMARY OF THE INVENTION

Some embodiments provide an account-based DRM system for distributing information. The system includes a number of units associated with a particular account. The system also includes a set of DRM computers, which receive a request for access to a particular set of information on the devices associated with the particular account. The set of DRM computers then generates a number of keys for the devices, whereby each individual key to each individual device allows the particular device to access the particular amount of data on the particular device.

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The set of DRM computers in some embodiments transmits the particular amount of data and the generated keys through a network to the devices associated with the particular account. The network is a LAN, a WAN or a network of networks, such as the Internet. In some of these embodiments, the set of DRM computers transmits the amount of data and keys to a device (for example, a computer), which is utilized to distribute the data amount and key (s) to the other devices associated with the account. In some embodiments, the set of DRM computers individually encrypts each key in a format used during its transport to the associated device and during use in that device.

Some embodiments provide a digital law management method (DRM) for the distribution of a data set to a user. The user has at least two devices for accessing the information. The method sends the information to the user in a protected format. From the set of DRM computers, the method also sends to the user (1) a first key that allows the user to access the protected information on the first device, and (2) a second key that allows the user to access the protected information on the other device.

In some embodiments, the first and second keys are used to decrypt the information. In other embodiments, the first and second keys are used to decrypt an additional key or keys used to encrypt the information. In some embodiments, the method individually encrypts the first and second keys before sending them to the first and second units.

Additionally, in some embodiments, the first device is a user computer and the second device is another device (for example, a portable media player) that synchronizes its information with the user computer. In some of these embodiments, (1) the user computer receives the information and the first and second key and (2) then provides the received information and the second key to the second device as the second device synchronizes its information with the user computer. In some embodiments, the user computer provides the information and the second key to the other device in the same protected format in which it received the information and the second key.

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Before the information and keys are sent to the user, (1) the method receives in some embodiments a request from the user to receive some information, and (2) generates the first and second keys in the set of DRM computers. In some embodiments, the user has more than two devices for accessing the information. In some of these embodiments, the method in the set of DRM computers generates more than two keys for the user after receiving the user's request for the information. In such a case, each individual generated key is intended to enable the user to access the information on a particular device assigned to the user.

In some of these embodiments, the method also individually encrypts each generated key in a format used during its transport to its associated unit and during its storage and use in that unit. The transportation, storage, or use of any key in these embodiments does not require the decryption of another key generated by the set of DRM computers for other devices or data.

In some embodiments, the first device stores its encrypted keys for decrypting DRM data in a first Key Case, while the second device stores the encrypted keys for decrypting DRM data in a second Key Case. The first and second Keybags have the same format in some embodiments. Using Keybags with the same format minimizes the exposure of keys during data transfer and keys between the first and second devices as one of these devices synchronizes their data and keys with the other device. Exposure is minimized as it eliminates operations that result from transforming data between two different key case formats. In some embodiments, the first and second units encrypt their respective key bags, whereas in other embodiments they do not encrypt their respective key bags but only store individually encrypted keys in these key bags.

The set of DRM computers also transmits other DRM material together with the encryption keys in some embodiments. Such additional DRM data include, in some embodiments, data in relation to the DRM system, such as DRM type, rules, etc. The additional DRM material also includes in some embodiments encryption key data (for example, the type of key etc.). Other embodiments may include other types of DRM materials.

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DESCRIPTION

The new features of the invention are set forth in the appended claims. However, for a more detailed explanation, a number of embodiments are written in the following figures.

Figure 1 shows an account-based DRM system according to some embodiments.

Figure 2 shows an example of a key case for transport for a user computer.

Figure 3 shows a transport key bag that includes all encryption keys that a device M can receive from the user computer during a synchronization operation.

Figure 4 shows that in some embodiments, the encryption key used to access a particular amount of data on a particular device is (1) generated and stored in the set of DRM servers, and (2) stored in the particular device.

Figure 5 conceptually illustrates a process that the set of DRM servers perform to process a request from a user account to purchase or purchase a license for a particular information.

Figure 6 conceptually illustrates a process that the set of DRM servers performs in some embodiments when it detects that a new device has been connected to a user account.

Figure 7 conceptually illustrates a process a user computer is performing when it needs to purchase or purchase a license for a particular information for a particular user account.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, a number of details will be included to facilitate the explanation. However, those skilled in the art will recognize that the invention may be carried out without the use of these particular details. In other cases, well-known structures and units are shown in the form of block diagrams so as not to burden the description of the invention with unnecessary details.

I. OVERVIEW

Some embodiments provide a digital law management method (DRM) for the distribution of a data set to a user. The user has at least two devices

534 641 for accessing the information. The method sends the information to the user in a protected format. From the set of DRM computers, the method also sends to the user (1) a first key that allows the user to access the protected information on the first device, and (2) a second key that allows the user to access the protected information on the other device.

In some embodiments, the first and second keys are used to decrypt the information. In other embodiments, the first and second keys are used to decrypt an additional key or keys used to encrypt the information. In some embodiments, the method individually encrypts the first and second keys before sending them to the first and second units.

Additionally, in some embodiments, the first device is a user computer and the second device is another device (for example, a portable media player) that synchronizes its information with the user computer. In some of these embodiments, (1) the user computer receives the information and the first and second key and (2) then provides the received information and the second key to the second unit as the second unit synchronizes its information with the user computer. In some embodiments, the user computer provides the information and the second key to the other device in the same protected format in which it received the information and the second key.

Before the information and keys are sent to the user, (1) the method receives in some embodiments a request from the user to receive some information, and (2) generates the first and second keys in the set of DRM computers. In some embodiments, the user has more than two devices for accessing the information. In some of these embodiments, the method in the set of DRM computers generates more than two keys for the user after receiving the user's request for the information. In such a case, each individual generated key is intended to enable the user to access the information on a particular device assigned to the user.

In some of these embodiments, the method also individually encrypts each generated key in a format used during its transport to its associated unit and during its storage and use in that unit. The transportation, storage or use of any key in these embodiments does not require

534 641 decryption of another key generated by the set of DRM computers for other devices or data.

In some embodiments, the first device stores its encrypted keys for decrypting DRM data in a first key case, while the second device stores the encrypted keys for decrypting DRM data in a second key case. The first and second Keybags have the same format in some embodiments. Using Keybags with the same format minimizes the exposure of keys during data transfer and keys between the first and second devices as one of these devices synchronizes their data and keys with the other device. Exposure is minimized as it eliminates operations that result from transforming data between two different key case formats. In some embodiments, the first and second units encrypt their respective key bags, whereas in other embodiments they do not encrypt their respective key bags but only store individually encrypted keys in these key bags.

In some embodiments, the set of DRM computers transmits other DRM material along with the encryption keys. Such additional DRM data include in some embodiments data in relation to the DRM system, such as DRM type, rules, etc. The additional DRM material also includes in some embodiments encryption key data (for example, the type of key etc.). Other embodiments may include other types of DRM materials.

IL CONTOBASED DRM SYSTEM

Figure 1 shows an account-based DRM system 100 according to some embodiments. This DRM system distributes information in a way that ensures the legal use of the information. As shown in Figure 1, DRM system 100 includes a set of DRM servers 110 which distribute information to a number of units assigned to B user accounts. This figure shows two sets of units associated with two accounts, Account 1 and Account B. The set of units for account 1 includes a user computer 115 and a number of portable media players 130.1 The example shown in figure 1 is the units for the two different user accounts mutually exclusive. This need not be the case in some embodiments. Some embodiments may allow a device (for example, a user computer, etc.) to process DRM information for two different user accounts.

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The set of DRM servers 110 connects to the user computers 115 and 120 via a computer network 125 such as a LAN, WAN, a network of networks (for example, the Internet), etc. Through this connection, the user computers 115 and 120 communicate with the set of DRM servers 110 to purchase, obtain a license for, update or otherwise receive information in certain embodiments. While in some embodiments, the set of DRM servers 110 sells or licenses information to the user computers, this set does not sell or license the information in other embodiments. In some embodiments, the set of DRM servers 110 only performs the distribution of information to authorized computers without any financial interest.

In some embodiments, the set of DRM servers 110 includes an information caching server that delivers encrypted information to a user computer 115 or 120 via the network 125 after another DRM server 110 determines that the computer 115 or 120 is entitled to the information. In some embodiments, the system 100 utilizes a number of caching servers to store information at various points in the network to increase the speed and efficiency of downloading information over the network.

As mentioned above, a user computer 115 or 120 assigned to a particular account communicates with the set of DRM servers 110 to purchase, license, update or otherwise receive information via the network 125 for that particular account. 1 some embodiments (1) provide the set of DRM servers 110 for each requested information in an encrypted format and (2) for each device associated with the request account provide an encryption key for decrypting the encrypted information.

Figure 1 shows an example where the set of DRM servers 110 distributes an encrypted amount of information (the information W) to the devices associated with the two different user accounts 1 and B. As shown in this figure, the set of DRM servers distributes the encrypted information W to both user computers 115 and 120 together with a set of encryption keys to access this information on each device associated with user accounts 1 and B.

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The set of DRM servers distributes the information W and each set of encryption keys in an encrypted format. In addition, in some embodiments, each encryption key in the set is individually encrypted. The set of DRM servers 110 provides, in some embodiments, the set of encryption keys in a key bag for transport. A Key Bag is a storage structure that stores the encryption keys in a special format. The key bag for transport is encrypted in its entirety for transport in some embodiments, while it is not encrypted for transport in other embodiments.

Figure 2 shows an example of such a Key Bag for transport 205 for the user computer 120. As shown in this figure, the user computer 120 extracts each individually encrypted key from the Key Bag for transport 205 and stores these keys in a Key Bag 210 for storage. The keys in the Keychain 210 are the same as the keys in the Keychain 205 (that is, they are individually encrypted in the same format as in the Keychain 205). The key cases 205 and 210 are also fully encrypted in some embodiments, while not encrypted in other embodiments.

Figure 1 illustrates that each user computer 115 or 120 stores the received encrypted information W and the encryption key it receives for accessing this information. Each user computer 115 or 120 also provides each portable media player 130 with which it synchronizes with the received encrypted information W and the encryption key that the user computer received for the portable media unit.

For example, as shown in Figure 1, the user computer 115 provides the unit 2 for the account 1 with the received encrypted information W and the encryption key for accessing the encrypted information W on the unit 2. The user computer 120, on the other hand, provides the unit Z for the account B with the received encrypted information W and the encryption key for accessing the encrypted information W on the unit Z.

In some embodiments, each user computer deletes an encryption key as it provides another device after the synchronization operation, whereas in other embodiments, each user computer maintains the storage of the encryption keys as it provides devices that synchronize their information with the computer.

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In some embodiments, each synchronizing unit stores the encryption keys it receives from its associated user computer in a Key Bag. Figure 3 shows an example of this for one of the units (unit M) associated with account B. This figure shows in particular a key bag for transport 305 which includes all encryption keys that a unit M can receive from the user computer 120 during a synchronization operation. As shown in this figure, the unit M extracts each individually encrypted key from the key bag for transport 305 and stores these keys in a key bag 310 for storage. The keys in the key bag 310 are the same as the keys in key bag 305 (that is, they are individually encrypted in the same format as in key bag 305). The key bags 305 and 310 are also fully encrypted in some embodiments, while not encrypted in other embodiments.

In some embodiments, the Key Case 205, 210, 305 and 310 all have the same format. The use of Key Bags of the same format minimizes key exposure during the transfer of encryption keys between the set of DRM servers, user computers, and the other devices associated with the accounts. Exposure is minimized because the use of the same format eliminates operations due to the transformation of data between two different formats for key bags. The individual encryption of each key also has the advantage that a device can decrypt and use any encrypted key for a particular information without decrypting an additional encryption key, which device does not need for that particular information.

Figure 4 shows that in some embodiments, the encryption key used to access a particular data set on a particular device is (1) generated and stored in the set of DRM servers, and (2) stored in the particular device. In particular, this figure shows a DRM architecture in which the set of DRM servers 110 generates and stores the encryption keys for each data set that this set distributes directly or indirectly to each device associated with each user account. This figure also shows that the user computers 115 and 120, which initially receive the DRM information for each account, store at least the encryption key for access to each set of information on the user computers. As mentioned above, in some embodiments, each user computer also stores the encryption key for accessing the received information on each device that synchronizes with the computer.

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Figure 4 also shows that each unit stores the encryption keys for access to any amount of information to which access is granted. In some embodiments, some of the set of DRM servers generated encryption key for a particular device intended for encrypting a data set on that particular device. In other embodiments, any such key is intended to decrypt another key or keys used by the particular device to decrypt the information.

Figures 1 and 4 show user computers 115 and 120 receiving data and encryption keys from the set of DRM servers and synchronizing data and encryption keys with other devices associated with accounts 1 and B. One skilled in the art will recognize that some embodiments may have multiple devices (e.g., computers, portable electronic or communications devices, etc.) that directly receive information from the set of DRM servers 110 through a communication network. Those skilled in the art will also recognize that the user computer 115 or 120 may be included in any type of device, such as a consumer or commercial electronic device, a media center for home use, a hub, etc.

As mentioned above, in some embodiments, the set of DRM computers transmits another DRM matrial along with the encryption keys. Such additional DRM data include in some embodiments data in relation to the DRM system, such as DRM type, rules, etc. The additional DRM material also includes in some embodiments data concerning the encryption key (for example, the type of key, etc.). ). Other embodiments may include other types of DRM materials.

III. KEY GENERATION AND DISTRIBUTION FLOW

Figures 5-7 show conceptually a number of processes for generating keys and distributing data and keys in some embodiments. These processes are described in connection with the purchase or licensing of a particular set of information. Those skilled in the art will recognize that these processes can be performed without any of the financial goals or transactions of other embodiments.

Figure 5 conceptually illustrates a process 500 that the set of DRM servers performs to process a request from a user account to purchase or purchase a license prior to a particular information. The information can be any form of information, such as a music file, a video file, a document, a picture, etc. As shown in this figure

534 641, the process 500 starts when it receives (at 505) a request for the particular amount of data from a user computer that synchronizes all the keys and data for a particular user account.

The process then performs (at 510) a set of one or more operations to complete the purchase or license transaction. Thereafter, the process (at 515) identifies all the devices associated with the particular user account. At 520, the process generates an encryption key for each device associated with the particular user account. The encryption key for each particular device is the key that allows the particular device to access an encrypted version of that particular data set.

At 525, the process then stores each encryption key that it generated at 520. Then, at 530, the process individually encrypts each key it generated at 520. At 530, the process also stores the individually encrypted keys in a Key bag. In some embodiments, process 500 first performs the encryption operation at 530 and then performs the storage operation at 525. At 535, the process sends the key bag created at 530 to the user computer and then terminates. Together with the Key Case or the Key Case, the process in some embodiments (at 535) transmits another DRM matrial, as discussed above.

Figure 6 conceptually illustrates a process 600 that the set of DRM servers performs in some embodiments when it detects that a new device has been connected to a user account. As shown in this figure, the process starts 600 (at 605) when it detects that a new device is being added to a user account. The process can detect this when a new user account is initiated or it can detect this when a user computer tries to synchronize data with a new device.

At 610, the process determines whether a new device can be added to the user account. In some embodiments, this determination includes determining whether a maximum number of devices has already been connected to the user account. If the process determines (at 610) that the device cannot be added, the process is terminated without connecting the device to the user account.

Otherwise, the process (at 615) identifies all data previously purchased or licensed by the user account. For each previously purchased or licensed data set then generate

534 641 process (at 620) a key for a new device. The process then stores (at 625) each generated key. Thereafter, the process (at 630) individually encrypts each key as it generated at 620.1, in some embodiments, the process 600 first encrypts each key and then stores the encrypted keys (i.e., first performs the encryption operation at 630 and then performs the storage operation at 625).

At 630, the process then stores the individually encrypted keys in a Key bag for transport, which it then sends (at 635) to the user computer associated with the new device. Together with the Key Case or the Key Case, the process transmits in some embodiments (at 635) other DRM material, as discussed above. After 635, the process ends.

Figure 7 conceptually illustrates a process 700 that a user computer performs when it needs to purchase or purchase a license for a particular information for a particular user account. As shown in this figure, the process (at 705) starts when the user computer sends a request to the set of DRM servers to purchase or purchase a license for a particular data set for the particular user account. Then, at 710, the process performs one or more operations to complete the purchase or license transaction.

At 715, the process then receives the requested amount of data in an encrypted format plus a transport key bag containing an encryption key for each device associated with the particular user account and which can access the encrypted information. In some embodiments, the encryption keys are individually encrypted in the key bag for transport.

At 720, the process extracts the encryption keys from the Keychain for transport and stores these keys in a Keychain in the user computer. The key bag for transport and the key bag in the computer have the same format in some embodiments. The process also marks (at 720) a record it retains for each particular synchronization unit associated with the particular user account. This check mark was used to alert the user computer at the next synchronization with the particular device that the user computer needs to download newly received encrypted data and encryption key (s) to the particular device. After 720, the process ends.

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IV. ENCRYPTION

As described above, several embodiments of the invention provide DRM processes and systems for distributing data. These processes and systems encrypt and decrypt data using encryption keys. Encryption of data involves transferring data from an interpretable form (called clear text) to a non-interpretable form (called cipher text) based on one or more encryption keys. Decryption of data involves transferring encrypted data to an interpretable form by using one or more encryption keys.

An encryption key is an information that controls the operation of an encryption algorithm. In symmetric encryption technology, the key used to encrypt data is the same as the key used to decrypt data. In asymmetric encryption technology, the same key is not used for encryption and decryption of data. In one method, for example, an encryption device utilizes a public key from a receiver to encrypt data and the receiver utilizes its private key to decrypt data.

Many of the characteristics of the embodiments described above can be implemented by a symmetric or asymmetric encryption method. In some embodiments, the encryption is also applied to a binary format of data. Although the unencrypted binary format for an amount of information can be difficult for a person to decipher, it can be deciphered by an application or operating system. On the other hand, an encrypted binary format for an amount of information should in principle not be decipherable with any application or operating system without first having been decrypted using one or more encryption keys.

Although the invention has been described with reference to a large number of specific details, those skilled in the art will recognize that the invention can be realized in other specific forms without thereby departing from the idea of ​​the invention. For example, several embodiments described above portray the portable devices as devices that receive DRM information only through their synchronization with other user computers. However, those skilled in the art will recognize that in some embodiments, the portable players could access the DRM server (s) through a network to receive DRM information without interacting with another interconnected computer that can receive and access DRM data. Thus, one skilled in the art will recognize that the invention is not limited by the illustrative details described but should instead be defined by the appended claims.

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