KR20110084144A - Method and apparatus for sending right object information between device and portable storage - Google Patents

Abstract

PURPOSE: A right object information transmission method and device thereof between a device and a portable storing device are provided to reduce an overhead and increase the speed of information transmission. CONSTITUTION: In a step of request receiving, a portable storing device receives predetermined request from a device. In a step of generating a format, a current permission state format including information about specified authority object according to the request is generated. In a step of transmitting, the generated current permit state format to transmit a device.

Description

Method and Apparatus for sending right object information between device and portable storage device {Method and Apparatus for sending right object information between device and portable storage}

The present invention relates to a method and apparatus for delivering rights object information. More particularly, the present invention relates to a device and a portable storage device for generating a current permission state format including permission information of a rights object, thereby reducing overhead of the information about the rights object. The present invention relates to a method and an apparatus for transmitting rights object information therebetween.

Recently, research on digital rights management (hereinafter referred to as "DRM") has been actively conducted, and commercial services using DRM have been introduced or are being introduced. The reason why the DRM should be rewritten can be derived from various characteristics of digital data. Unlike analog data, digital data can be copied without loss, easy to reuse and process, and easily distributed to third parties. It is easy to do. In contrast, digital content requires a lot of money, effort and time to produce. Thus, if unauthorized copying and distribution of digital content is tolerated, it will violate the interests of the digital content creator and the creative motivation of the digital content creator will be reduced, which is a major impediment to the vitalization of the digital content industry.

Efforts have been made to protect digital content in the past, but in the past, the focus was primarily on preventing unauthorized access to digital content. In other words, access to digital content was granted only to some people who paid for it. Thus, the payer could access unencrypted digital content, while the other could not access digital content. However, intentionally distributing digital content accessed by a payer to a third party allows the third party to use the digital content without paying for it.

To solve this problem, the concept of DRM was introduced. DRM allows anyone with unlimited access to any encrypted digital content, but requires a license called the Rights Object to decrypt and play the encrypted digital content. Therefore, applying the DRM can effectively protect digital content unlike the existing.

The concept of DRM is described with reference to FIG. 1. DRM is about how to treat protected content (hereinafter referred to as encrypted content) in the same way as encryption or scramble and the rights objects that allow access to the protected content.

Referring to FIG. 1, it includes users 110 and 150 who want to access content protected by DRM, a Contents Issuer 120 supplying the content, and a right to access the content. Rights Issuer 130 issuing a rights object that exists, and Certificate Authority 140 issuing a certificate.

In operation, user A 110 may obtain desired content from content provider 120, which obtains DRM-protected encrypted content. The user A 110 may obtain a license for playing the encrypted content from the rights object received from the rights object issuer 130. The user A 110 having the rights object can play the encrypted content. Since the encrypted content can be freely distributed or distributed, the user A 110 can freely transmit the encrypted content to the user B 150.

User B 150 needs a rights object in order to play the received encrypted content, which can be obtained from the rights object issuing agency 130. Meanwhile, a certification authority issues a certificate indicating that the content provider 120, the user A 110, and the user B 150 are legitimate users. The certificate may be inserted into the device from the time of manufacturing the device of the users 110 and 150, but the certificate may be reissued from the certification authority 140 when the certificate expires.

Meanwhile, as shown in FIG. 1, in addition to directly transferring the right object or the encrypted content between the devices between the device A 110 and the device B 150, recently, the right object and the encrypted content through the portable storage device. Techniques to convey this have been tried.

In general, portable storage devices have lower data storage capacity or data processing speed than devices, and thus, there is a need for efficient management of data transfer between the device and the portable storage device.

An object of the present invention is to reduce the overhead and increase the speed of information delivery in transferring information about a rights object between a device and a portable storage device by generating a current permission state format including permission information of the rights object. .

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, a method for delivering rights object information between a device and a portable storage device according to an embodiment of the present invention includes receiving a predetermined request from a device, and information on a rights object specified according to the request. Generating a current grant status format comprising a; and transmitting the generated current grant status format to the device.

In order to achieve the above object, a method for transferring rights object information between a device and a portable storage device according to an embodiment of the present invention includes the steps of a device transmitting a predetermined request to the portable storage device and a rights object specified according to the request. And receiving a current permission status format that includes information about.

In order to achieve the above object, a portable storage device according to an embodiment of the present invention is connected to a device for performing an interface, a storage module for storing a rights object, and at the request of the device received through the interface unit. A control module for determining whether to generate a current permission state format, and searching for the right object specified by the request in the storage module according to the determination result, and converting the current permission state format including information on the found right object. It includes a data format generation module for generating.

In order to achieve the above object, a device according to an embodiment of the present invention generates an interface connected to a portable storage device to perform communication, and a predetermined request to be transmitted to the portable storage device through the interface, And a control module for obtaining the information on the specified rights object from the current permission status format when the current permission status format including the information on the rights object specified in accordance with the interface is received by the interface.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims.

According to the method and apparatus for transmitting rights object information between the device and the portable storage device of the present invention as described above, it is possible to reduce the overhead in transferring information about the rights object between the device and the portable storage device, and to increase the speed of information delivery. There is an advantage.

1 is a diagram illustrating the concept of a general DRM.
2 is a view briefly explaining the concept of DRM between a portable storage device and a device.
3 shows the format of a rights object according to a preferred embodiment of the present invention.
FIG. 4 is a table showing the types of restrictions each permission shown in FIG. 3 may have.
5 is a diagram illustrating an example of a mutual authentication process between a device and a multimedia card.
6 is a diagram illustrating a DRM process using a transmission sequence counter according to an embodiment of the present invention.
7 illustrates a basic structure of a CPSF according to an embodiment of the present invention.
8 is a diagram illustrating a structure of a CPSF for a general rights object according to an embodiment of the present invention.
9 is a diagram illustrating a specific limited information field according to an embodiment of the present invention.
10 is a diagram showing a CPSF structure for a child rights object according to an embodiment of the present invention.
11 is a diagram illustrating a CPSF structure for a parent rights object according to an embodiment of the present invention.
12 is a diagram illustrating a composite form of CPSF for a general rights object and CPSF for a child rights object according to an embodiment of the present invention.
FIG. 13 is a diagram illustrating a composite form of a CPSF for a general rights object and a CPSF for a parent rights object according to an embodiment of the present invention.
14 is a flowchart illustrating a process of transferring rights object information between a device and a multimedia card according to an embodiment of the present invention.
15 is a block diagram illustrating a portable storage device according to an embodiment of the present invention.
16 is a functional block diagram showing the configuration of a device according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Prior to the description, the meaning of terms used in the present specification will be briefly described. However, it is to be noted that the description of the terms is intended to help the understanding of the present specification, and thus, the terms are not used to limit the technical spirit of the present invention unless explicitly stated as limiting the present invention.

Public-key Cryptography

Also known as asymmetric encryption, this means encryption when the key used to decrypt data and the key that encrypts the data are composed of different encryption keys. In public key cryptography, an encryption key consists of a pair of public and private keys. The public key does not need to be kept secret and can be easily known to the public, and the private key must be known only to the specific device itself. Such a public key encryption algorithm is open to the public, and public key encryption has a characteristic that a third party has an encryption algorithm, an encryption key, and an encrypted sentence, and cannot know the original text or is very difficult to know. Examples of public key encryption algorithms include a Diffie-Hellman method, an RSA method, an ElGamal method, and an elliptic curve method. In the case of the public key encryption method, the data encryption speed is about 100 to 1000 times slower than the symmetric key encryption method, so it is used for key exchange or digital signature rather than for encrypting the content itself.

Symmetric-key Criptography

Also known as secret key encryption, this means an encryption method in which the key used to encrypt data and the key used to decrypt data are the same. As an example of such a symmetric key encryption, the DES scheme is most commonly used, and recently, an application using the AES scheme is increasing.

Digital Signature

Used by the signer to indicate that a document has been created. Examples of such digital signatures include RSA digital signatures, ElGamal digital signatures, DSA digital signatures, and Schnorr digital signatures. In the case of an RSA digital signature, the sender of the encrypted message encrypts and transmits the message with its private key, and the receiver decrypts the message encrypted with the sender's public key. In this case it is proved that the encryption of the message is by the sender.

Random number

Pseudo-Random number is used because it means a random number or string, and actually generating a complete random number is expensive.

Portable storage device

The portable storage device used in the present invention includes a nonvolatile memory having a property such as a flash memory that can read, write, and erase, and means a storage device that can be connected to a device. Examples of such storage devices include smart media, memory sticks, CF cards, XD cards, multimedia cards, and the like, which will be described below with reference to multimedia cards.

Rights object

A license that includes the right to use encrypted content and limitations on that right. A detailed description of the rights object used in the present invention will be described later with reference to FIGS. 3 and 4.

2 is a view briefly explaining the concept of DRM between a portable storage device and a device.

Device A 210 may obtain encrypted content from content provider 220. Encrypted content refers to content protected by DRM. In order to use encrypted content, a rights object for the content is required.

The device A 210 which obtains the encrypted content makes a rights object request to the rights object issuing authority 230 to obtain a right to use the encrypted content. When the rights object is received from the rights object issuer 230, the device A 210 may use the encrypted content.

On the other hand, when trying to deliver the rights object to the device B 250, the device A (210) can be delivered using a portable storage device. In one embodiment, the portable storage device may be a multimedia card 260 having a DRM function. In the following embodiments, a multimedia card is used as an example of the portable storage device, but the present invention is not limited thereto.

The device A 210 may move or copy the rights object to the multimedia card 260 after mutual authentication with the multimedia card 260. If the device A 210 then wants to play the encrypted content, the device A 210 requests the playing card from the multimedia card 260 to play it from the multimedia card 260 (for example, a content encryption key). ; CEK)) to play the encrypted content.

Meanwhile, the device B 250 may also play back the content by requesting the multimedia card 260 to play a specific content after mutual authentication with the multimedia card 260 in which the rights object is stored. In addition, the device B 250 may receive or copy the rights object from the multimedia card 260.

3 shows the format of a rights object according to a preferred embodiment of the present invention.

The rights object is largely composed of a version 300 part, an asset 320 part, and a permission 340 part.

The version 300 portion represents version information of the DRM system, the asset 320 portion contains information about the content data whose consumption is governed by the rights object, and the permission 340 portion is for the protected content data. Contains information about the actual use or activity allowed by the Right Issuer.

Among the information stored in the asset 320, id is an identifier for identifying the rights object, and uid is information for identifying content whose usage is governed by the rights object. Uniform Resource Identifier (hereinafter referred to as URI).

KeyValue stores the binary key value used to decrypt the DRM content. This is called a content encryption key (hereinafter referred to as CEK). The CEK is a key value for decrypting the encrypted content that the device intends to use, and the device can use the content by receiving the CEK value from the multimedia card in which the rights object is stored.

The permission 340 is a right to use the content allowed by the rights provider. The permission types include Play, Display, Execute, Print, and Export.

The playback element refers to the right to express DRM content in the form of audio / video. For example, if the DRM content is about a movie or music, playback may be set as an element of permission of the right object to use the DRM content. If a Constraint element is specified for the reproduction permission, the DRM agent grants the reproduction right according to the restriction element. If no restrictive element is specified, the DRM agent grants unlimited reproduction right.

The display element refers to the right to present the DRM content to the visual device.

Execution element refers to the right to execute DRM content such as Java games or other applications.

The printing element means the right to create a hard copy of DRM content such as an image such as JPEG.

The term playback is hereinafter used as a generic term for the above-mentioned reproduction, display, execution and printing.

The export factor, on the other hand, refers to the right to export DRM content and corresponding rights objects to a DRM system or content protection structure other than the OMA DRM system.

Export licenses have a finite element. The definitive element specifies which DRM system or content protection structure the DRM content and rights object can be exported to. There are two modes of export permissions: Move and Copy. In the case of Move, when exporting a rights object to another system, the rights object in the current DRM system is deactivated, but in the case of Copy, the rights object in the current DRM system is not deactivated.

FIG. 4 is a table showing the types of restrictions each permission shown in FIG. 3 may have.

Authorization limits the consumption of digital content by the limitations it has.

Count limit 400 has a positive integer value and specifies the number of grants granted to the content.

Datetime constraint 410 specifies a time range constraint for the permission, and optionally has start and end elements. If the start element is present, the connection is not allowed before the specified time / date. If the end element is present, the connection is not allowed after the specified time / date.

Interval qualification 420 specifies a period of time during which rights may be performed on the DRM content. If there is a Start element, consumption of DRM content is allowed for the time specified in the duration element before the specified time / date, if the end element is present.

Accumulated definition 430 specifies the maximum duration of the measured usage time for which rights can be performed on the DRM content. The DRM agent does not allow access to the DRM content after the cumulative interval specified by the Accumulated Qualified Value has elapsed.

Individual definition 440 specifies an individual to whom content is bound.

System definition 450 specifies the DRM system or content protection structure in which content and rights objects can be exported. The Version element specifies version information of the DRM system or content protection structure, and the SID element specifies the name of the DRM system or content protection structure.

On the other hand, when the multimedia card and the device wants to communicate, the multimedia card and the device must be mutually authenticated.

5 is a diagram illustrating an example of a mutual authentication process between a device and a multimedia card.

In the subscript of an object, H means host (device) owned or created by the device, and S means multimedia card owned or created by the multimedia card.

The mutual authentication process is a process of confirming that the device 510 and the multimedia card 520 are mutually legitimate devices, and exchanging random numbers for generating a session key between the two, and using the random numbers obtained through the mutual authentication process. Can be generated. In FIG. 7, the description above the arrow means a command for requesting an operation from the counterpart device, and the description below the arrow indicates a parameter or data to be moved according to the command. In one embodiment, all commands are performed by the device 510 in the mutual authentication process, and the multimedia card 520 performs an operation according to the command.

For example, the command of mutual authentication response (S20) is that when the device 510 sends the multimedia card 520, the multimedia card 520 receives a command to the device with its ID (ID _S ) and the certificate _S and the random number _S encrypted. Send it. In other embodiments, commands may be issued by both device 510 and multimedia card 520. In this case, the mutual authentication response (S20) may send the ID (ID _S ) and the certificate _S and the encrypted random number _S together while the multimedia card 520 sends to the device 510. Describe the detailed mutual authentication process.

The device 510 and the multimedia card 520 use key pairs corresponding to each other when exchanging important information such as random numbers. That is, the device 510 and the multimedia card 520 each include a key pair, one key pair consisting of two corresponding keys. The device 510 includes a first key and a second key, which may be decrypted by the second key when encrypted with the first key, and decrypted by the first key when encrypted by the second key. One of these keys can be released to other devices or multimedia cards. That is, the first key is used as a key that can be read by other devices as a public key, and the second key is used as a private key so that other devices can not read and only the device 510 can read it. Similarly, the multimedia card 520 includes a third key and a fourth key, the third key being made public so that other devices can read it, and the fourth key can be read only by the multimedia card 520.

The device 510 requests mutual authentication from the multimedia card 520 (S10). While making a mutual authentication request, the device sends the device public key PuKey _H that the multimedia card has. In an embodiment, in operation S10, the device public key PuKey _H is transmitted through a device certificate Cert _H issued by a certification authority to the device 510. The device certificate (Cert _H ) contains the device public key (PuKey _H ) and the digital signature of the certification authority. Upon receiving the device certificate Cert _H , the multimedia card 520 may confirm whether the device 510 is a legitimate device, and obtain a device public key PuKey _H. The device certificate (Cert _H ) and the device ID (ID _H ) may be sent together.

The multimedia card 520 determines whether the device certificate Cert _H has expired and checks whether the device certificate Cert _H is valid by using a Certificate Revocation List (hereinafter referred to as "CRL"). Check (S12). If the validity period of the device certificate Cert _H has passed or the certificate of the device registered in the CRL, the multimedia card 520 may refuse mutual authentication with the device 510. In this case, the multimedia card 520 reports the result to the device 510, and the device 510 stops the DRM procedure. On the other hand, when the validity period of the device certificate (Cert _H ) has passed or is revoked, the device 510 may proceed to obtain a device certificate (Cert _H ). In the case of a certificate of a device not registered in the CRL, the multimedia card 520 obtains the device public key PuKey _H through the device certificate Cert _H. Then continue with the DRM procedure.

Then, the multimedia card 520 generates a random number _S (S14). The generated random number _S is encrypted with the device public key PuKey _H. Then, the mutual authentication response command is received by the device 510, or the multimedia card 520 sends a mutual authentication response command to the device 510, and a mutual authentication response process is performed (S20). In the mutual authentication response process, the multimedia card 520 sends a multimedia card public key PuKey _S and an encrypted random number _S to the device. In one embodiment, the multimedia card certificate CERT _S is sent instead of the multimedia card public key PuKey _S. In another embodiment, the multimedia card 520 sends the multimedia card certificate (CERT _S ), the encrypted random number _S and the issue date information of the CRL of the multimedia card 520 to the device 510. This is to allow the device 510 and the multimedia card 520 to share the latest CRL. On the other hand, the reason for sending the CRL issuance date information instead of sending the CRL immediately is to reduce the overhead incurred in the mutual authentication process because the CRL is not frequently updated. In case of transmitting CRL issuance date information, it is encrypted with random number _S or separately. In addition, the multimedia card ID (ID _S ) may be additionally transmitted together.

The device 510 receives the multimedia card certificate (CERT _S ) and the encrypted random number _S , verifies that the multimedia card 520 is justified by verifying the certificate, obtains the multimedia card public key (PuKey _S ), and encrypts the random number _S. Is then decrypted with a device private key (PrKey _H ) to obtain a random number _S (S22). During the certificate verification process, it is determined whether the certificate is valid and whether it is registered in the CRL. Then, the device 510 generates a random number _H (S24). The generated random number _H is encrypted with the multimedia card public key PuKey _S (S26). Then, the final mutual authentication request process (S30) is performed. In the final mutual authentication request process (S30), the device 510 transmits an encrypted random number _H to the multimedia card 520. In one embodiment, the device 510 sends the multimedia card 520 to the multimedia card 520 further including the date of issue of the CRL of the device 510 together with the encrypted random number _H. In this case, the issue date information of the CRL may be encrypted together with the random number _H or separately.

The multimedia card 520 receives and decrypts the encrypted random number _H (S10). Accordingly, the device 510 and the multimedia card 520 generate a session key by using the random number generated by the device 510 and the random number generated by the opponent (S40 and S42). In this embodiment, the randomness is generated and used in both the device 510 and the multimedia card 520 to greatly increase the randomness and to enable secure mutual authentication. That is, even if the randomness is weak on either side, the randomness can be compensated on the other side.

Through these processes, the device 510 and the multimedia card 520 can authenticate each other and share a session key. On the other hand, both parties need to check whether the session key that they have and the session key that the other party has the same, this is done in the final mutual authentication response process (S50). That is, when one party encrypts and transmits information that the other party knows using the generated session key, the other party can determine whether the session keys are the same by decrypting its own session key. In one embodiment, the multimedia card 520 sends the device encrypted with the session key the random number _H generated by the device 510. In this case, the device 510 receives the random number _H encrypted with the session key, decrypts it with its own session key, determines whether the random number _H is restored, and checks whether the session key is properly generated (S52). In another embodiment, the device 510 waits for a suitable time after the final mutual authentication request (S30) and encrypts the random number _S generated by the multimedia card 520 with the session key generated by the device 510 to the multimedia card 520. send. In this case, the multimedia card 520 may check whether the session key is properly generated by decrypting the random number _S encrypted with its session key. In one embodiment, if the session key is not generated properly, the mutual authentication process is performed from the beginning. In another embodiment, if the session key is not properly generated, the DRM procedure between the device 510 and the multimedia card 520 is terminated.

In the present embodiment, the random number may generate a random number through a random number generation module (not shown) as described above, but any one or multiple numbers selected from among a plurality of numbers already generated and stored in the device or the multimedia card It may be a combination of numbers. In addition, the random number may simply mean a number, or may be a string including a character other than a number. Accordingly, the meaning of the random number used in the present specification may be interpreted to include a number or a combination of numbers or a string generated through the random number generation module, and also a single number or string selected from stored numbers or strings or It may be interpreted to include a combination of a plurality of numbers or strings.

According to the embodiment of the present invention, more secure DRM is enabled by using two random numbers in the mutual authentication process between the device 510 and the multimedia card 520, and whether the mutual authentication process is properly performed by providing a session key verification process. To judge. According to an embodiment of the present invention, a secure DRM operation between the device 510 and the multimedia card 520 is possible with the session key generated during the mutual authentication process, but further includes a verification process after the mutual authentication process to enable a more secure DRM operation. You can. This will be described with reference to FIG. 8.

6 is a diagram illustrating a DRM process using a transmission sequence counter according to an embodiment of the present invention.

Various operations are possible between the device 510 and the multimedia card 520 in the DRM process. There may be a DRM for the rights object, such as moving, copying, or deleting the rights object, and there may be a DRM for the content, such as playback. These DRM processes presuppose mutual authentication between the device 510 and the multimedia card 520. That is, in order to perform the DRM process, the device 510 and the multimedia card 520 first perform mutual authentication (S100). As a result of mutual authentication, the device 510 and the multimedia card 520 generate the same session key (S110 and S112). After sharing the session key, DRM processes can be performed, and a Send Sequence Counter (SSC) is used for more secure DRM. The transmission sequence counter is included in an application protocol data unit (APDU) and increments every time an APDU is transmitted. For example, therefore, if someone intercepts one or more APDUs, a discontinuity of the transmission sequence counter included in the APDU occurs. In addition, even if someone inserts the APDU, the discontinuity of the transmission sequence counter occurs. A DRM process using a transmission sequence counter will be described with reference to FIG. 4.

The device 510 and the multimedia card 520 initialize the transmission sequence counter for the DRM process after mutual authentication (S100) (S120 and S122). In one embodiment, the transmission sequence counter is initialized to a combination of random numbers _H and random numbers _S. For example, when the size of the transmission sequence counter is 2 bytes in total, the transmission sequence counter is initialized by combining the random number _H and the last 1 byte of the random number _S. For example, when the last digit of the random number _H and the random number _S ends with '01010101' and '11111110', the transmission sequence counter is initialized to '0101010111111110'. By obtaining the initialization value of the transmission sequence counter by using the random number _H and the random number _S , the randomness can be improved more than the case of initializing to '0000000000000000', and thus a more secure DRM process is possible.

When the device 510 issues a DRM command to the multimedia card 520, the device 510 includes a transmission sequence counter in the APDU (S130). If all 10 APDUs are transmitted in the DRM command, the transmission sequence counter is incremented by 1 for each APDU from the initial value '0101010111111110'. Then, the multimedia card S120 checks the transmission sequence counter to determine whether an illegal APDU is inserted in the middle or intercepts the original APDU (S132).

When the multimedia card 520 issues a DRM command to the device 510, the multimedia card 520 includes a transmission sequence counter in the APDU (S140). In one embodiment, the initial value of the transmission sequence counter uses an initial value initially initialized. For example, if all 10 APDUs are transmitted in the DRM command, the transmission sequence counter is incremented by 1 for each APDU from the initial value '0101010111111110'. In another embodiment, the initial value of the transmission sequence counter is based on the last transmission sequence counter value. For example, if the final transmission sequence counter value is '1000000000000000', then the transmission sequence counter value of the next APDU starts from '1000000000000001'. Then, the device S110 checks the transmission sequence counter to determine whether an illegal APDU is inserted in the middle or intercepts the original APDU (S142).

Incrementally increasing the transmission sequence counter is an example, and in the case where the transmission sequence counter is sequentially decreased from an initial value or when the increment or decrement of the transmission sequence counter is not 1, Should be interpreted as being included.

In each embodiment according to the present invention, the data to be transmitted and the above-described SSC value may be encrypted and included in an APDU transmitted between the device and the multimedia card, even if not specifically mentioned.

Meanwhile, the right object can be moved or copied between the mutually authenticated device and the multimedia card, and the multimedia card can also store the right object. When the rights object is stored in the multimedia card, the device may request a playback from the multimedia card in order to play the encrypted content. When the device plays content through the rights object stored in the multimedia card, the limited information set in the rights object must be updated.

The update of the rights object stored in the portable storage device may be performed on the device. In the related art (for example, when the portable storage device is an SD card), the entire rights object may be moved from the portable storage device to the device for updating the rights object. It was. Since the movement of the entirety of the rights object at every update of the rights object is an overhead in communication between the device and the portable storage device, the present invention includes basic information for identifying the rights object when updating the rights object and permission information of the rights object. Data format can be moved.

In addition, according to the present invention, even when the device requests confirmation of the permission information of the rights object stored in the portable storage device, the data format can be shifted to reduce the overhead of communication between the device and the portable storage device, and to promptly only necessary information. Can be sent.

As described above, a data format including basic information for identifying a rights object and permission information of the rights object is referred to as a current permission status format (CPSF).

7 illustrates a basic structure of a CPSF according to an embodiment of the present invention.

In the illustrated content identifier field of the CPSF, a content identifier for identifying specific content that can be used through the rights object is set.

In the content encryption key field, a CEK value capable of decrypting encrypted content is set. The device can use the content by receiving the CEK value.

In the Message Digest field, a message summary value is set. This value is for integrity protection of transmitted data. The message summary value may be generated by a published hash algorithm (eg Security Hash Algorism1).

In the permission information field, permission information of the rights object may be set.

The contents of the CPSF may vary depending on the type of the rights object. In the present invention, the types of the rights object are largely divided into three types: general RO, child RO, and parent RO. It can be divided into.

A generic rights object refers to a rights object that is not related to the subscription model or subscription business model described in the OMA DRM v2.0 REL.

Meanwhile, rights objects corresponding to the subscription model described in the OMA DRM v2.0 REL can be divided into child rights objects and parent rights objects. The child rights object contains the CEK, which is the right to use the encrypted content, and the parent rights object contains the permission elements and restrictions on the permission elements. Other child rights and parent rights objects are described in detail in the OMA DRM v2.0 REL.

Hereinafter, CPSF according to the type of rights object will be described.

8 is a diagram illustrating a structure of a CPSF for a general rights object according to an embodiment of the present invention.

The contents of the content identifier field, the content encryption key field, and the message summary field are the same as described with reference to FIG. 7. Meanwhile, the CPSF structure for the general rights object may include one or more permission information fields as shown in the figure. The subfields constituting each permission information field will be described below.

First, the type field includes identification information for identifying the type of the rights object, and an example of identification information according to the rights object type is shown in Table 1.

Right Object Type Identification information (1 byte) General rights object 0x01 Child Rights Object 0x02 Parent Rights Object 0x03

As illustrated in Table 1, 0x01 may be set in the type field of FIG. 8.

In the rights object index field and the asset index field, an internal rights object identifier and an internal asset identifier on the multimedia card are set, respectively. These internal rights object identifiers and internal asset identifiers may be used to identify each rights object and asset stored in the multimedia card.

In the permission index field, identification information for identifying the type of permission is set. An example of such a permission index is shown in Table 2.

Name of permission Permission index (1 byte) All 0x00 Play 0x01 Display 0x02 Execute 0x03 Print 0x04 Export 0x05 Move 0x06 Copy 0x07

Description of the type of permission has already been described with reference to FIG. 3.

In the limited number field, the number of limited information to be described later is set.

One piece of permission information may be included in one permission information, and each limit information may include a limit index field and a limit element field. The limit index is an identifier for identifying the type of limit and an example thereof is shown in Table 3.

Name of the restriction Restriction Index (1 byte) None 0x00 Count 0x01 Time count 0x02 Interval 0x03 Accumulated 0x04 Datetime 0x05 Individual 0x06 System 0x07

In the qualifier element field, specific content of the restriction is set.

9 is a diagram illustrating a specific limited information field according to an embodiment of the present invention.

The numbers in parentheses in each field shown indicate the number of bytes each field can have.

The count limit 510 limits the use of the rights object by specifying the number of times that the content can be played back through the rights object in the 2-byte subfield.

The time count limit 520 includes a count and a timer subfield and limits the use of the rights object by specifying the number of times the content can be played during the time set in the timer field.

Interval qualification 530 specifies the time interval in which the rights object can be written for DRM content in time subfield 535.

Accumulated qualification 540 limits the use of the rights object as the maximum duration of usage time that the rights object can be written to the DRM content. Therefore, the DRM agent does not allow access to the DRM content if the cumulative time the user has used the rights object exceeds the time interval specified by the Accumulated limited value.

Datetime constraint 550 specifies the time range for the grant in the two time subfields and optionally has a start time or end time. If there is a start time, consumption of DRM content is allowed after the specified time / date and before the specified time / date if there is an end time.

Individual definition 560 specifies an individual to whom content is bound. That is, the use of the rights object is restricted by using the Uniform Resource Identifier (URI) of the individual whose content is bound. Therefore, the DRM agent does not allow access to the DRM content unless the user identity associated with the device matches the identity of the user who is allowed to use the content.

System definition 570 specifies a DRM system or content protection structure to which content and rights objects can be exported. The DRM system version subfield specifies version information of the DRM system or content protection structure, and the DRM system subfield specifies the name of the DRM system or content protection structure.

10 is a diagram showing a CPSF structure for a child rights object according to an embodiment of the present invention.

Since there is only one child rights object that can be used for a specific content, the illustrated CPSF may include one permission field.

In the illustrated CPSF, contents set in the content identifier field, the content encryption key field, and the message summary field are as described with reference to FIG. 7.

Among the subfields of the permission information field, the type field includes identification information for identifying the type of the rights object, as shown in Table 1 below.

In the parent rights object identifier field, identification information of the parent rights object may be set, and a URL address of a child rights object issuer may be set in the URL field.

11 is a diagram illustrating a CPSF structure for a parent rights object according to an embodiment of the present invention.

The content identifier field is as described with reference to FIG. 7. However, since the parent rights object following the OMA DRM v2.0 REL subscription model does not have a content encryption key and a message summary value, the content encryption key field and the message summary field may be set to null values.

Meanwhile, since there is only one parent rights object that can use specific DRM content, the illustrated CPSF can include one permission information.

The type field in the subfields of the permission information field is as described and described in Table 1 below.

In the Parent Right Object Identifier field, an identifier for identifying a parent rights object is set.

In addition, the contents set in the permission index field, the limit number field, and the limit information field are as described with reference to FIG. 8.

Meanwhile, the multimedia card may simultaneously store a general rights object and a child rights object capable of playing the same content, or simultaneously store both a general rights object and a parent rights object capable of playing the same content. In this case the CPSF provided to the device from the multimedia card is shown in FIGS. 12 and 13.

12 is a diagram illustrating a composite form of a CPSF for a general rights object and a CPSF for a child rights object according to an embodiment of the present invention.

The content identifier field, content encryption key field and message summary field of the illustrated CPSF are as described with reference to FIG. 7. In addition, the permission information field of the illustrated CPSF includes a permission information field for a general rights object and a permission information field for a child rights object, and description of each permission information field is as described with reference to FIGS. 8 and 10. .

FIG. 13 is a diagram illustrating a composite form of a CPSF for a general rights object and a CPSF for a parent rights object according to an embodiment of the present invention.

The content identifier field, content encryption key field and message summary field of the illustrated CPSF are as described with reference to FIG. 7. In addition, the permission information field of the illustrated CPSF includes a permission information field for a general rights object and a permission information field for a parent rights object, and description of each permission information field is as described with reference to FIGS. 8 and 11. .

14 is a flowchart illustrating a process of transmitting permission information of a multimedia card according to an embodiment of the present invention.

When the device 610 and the multimedia card 620 finishes mutual authentication (S210), the device 610 and the multimedia card 620 encrypt and transmit data to be transmitted to each other using the session key generated as a result of the mutual authentication (S210). If encrypted data is received, it can be decrypted.

When the device 610 requests the information of a specific rights object from the multimedia card 620 (S220), the multimedia card 620 searches for the rights object desired by the device 610 among the rights objects stored therein (S230). ). When requesting the rights object information (S220), the device 610 may transmit a rights object identifier for identifying the rights object to the multimedia card 620 in order to specify the desired rights object. In another embodiment, the device 610 may transmit a content identifier for identifying specific content. In this case, the multimedia card 620 may search for a rights object for playing the content identified by the content identifier. have.

When the specific rights object desired by the device 610 is searched, the multimedia card 620 determines the type of the searched rights object and generates the above-described CPSF data according to the type of the rights object (S240). The CPSF generated by the multimedia card 620 may have a structure as described with reference to FIGS. 7 to 13 according to the type of the retrieved rights object. That is, when the retrieved rights object is a general rights object, the multimedia card 620 may generate a CPSF having a structure as shown in FIG. 8. If the retrieved rights object is a child rights object, the CPSF as shown in FIG. 10 may be generated, and if the retrieved rights object is a parent rights object, the CPSF as shown in FIG. 11 may be generated.

In addition, when the general rights object and the child rights object are searched at the same time, the CPSF as shown in FIG. 12 may be generated. When the general rights object and the parent rights object are searched at the same time, the CPSF as shown in FIG. 13 may be generated. Can be. If the rights object information request S220 of the device 610 is for confirming permission information of a specific rights object, the multimedia card 620 may set the content encryption key field to a null value when generating the CPSF.

When the CPSF is generated, the multimedia card 620 transmits the CPSF generated by itself as the rights object information (S250). In another embodiment, the multimedia card 620 may store the CPSF generated by the multimedia card 620 and allow the device 610 to access it.

The device 610 receiving the CPSF may obtain permission information of the right object from the CPSF (S260).

On the other hand, even when the device 610 makes a playback request to the multimedia card 620 storing the rights object in order to play the specific content, the multimedia card 620 may generate the CPSF.

For example, when the device 610 makes a request to the multimedia card 620 to play a specific content, the multimedia card 610 searches for a right object that can play the content, and matches the type of the searched right object. The CPSF may be generated and sent to the device 610. The device 610 may obtain a content encryption key for playing the specific content through the received CPSF, and may also check the limited information on the playing right such as how much of the right to play the specific content remains.

In addition, even if the device 610 needs to update the rights object stored in the multimedia card 620, it is necessary not to transmit the entire rights object from the multimedia card 620 to the device 610 but by transmitting only the aforementioned CPSF. You may also want to update the permissions.

Accordingly, when the multimedia card 620 according to the embodiment of the present invention receives a predetermined request from the device 610, the multimedia card 620 may perform the process of step S230 or less in FIG. 14. In this case, the request of the device 610 for the multimedia card 620 to generate a CPSF for the specific rights object is stored in the request for permission information of the specific rights object, the playback request for the specific content, and the portable storage device as described above. Update request, etc., when a specific rights object that needs to be updated in the device. The generated CPSF may be transmitted to the device 610 as information on the rights object specified by the request of the device 610.

15 is a block diagram illustrating a portable storage device according to an embodiment of the present invention.

Modules used in this embodiment and the following embodiments refer to software that performs specific functions or hardware components such as FPGAs or ASICs. However, modules are not meant to be limited to software or hardware. The module may be configured to be in an addressable storage medium and may be configured to play one or more processors.

Thus, as an example, a module may include components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, procedures, subroutines. Or segments of program code, drivers, firmware, microcode, circuitry, data, database, data structures, tables, arrays, and variables. The functionality provided within the components and modules may be combined into a smaller number of components and modules or further separated into additional components and modules. In addition, the components and modules may be implemented to play one or more CPUs in a device or a multimedia card.

In order to perform the DRM process, the portable storage device 600 should have a security function, a function of storing a content object, a rights object, its own certificate and a CRL, a function of exchanging data with a device, and a DRM management function. There should also be a function for CPSF generation.

The multimedia card 600 for this purpose is an encryption module 630 having a security function, a storage module 640 having a storage function, an interface 610 for exchanging data with a device, and each component for performing a DRM process. A control module 620 for controlling the module and a data format generation module 650 for generating CPSF data.

Interface 610 allows portable storage 600 to be connected with the device.

Basically, the portable storage device is connected to the device, which means that the portable storage device and the interface of the device are electrically connected to each other, but this is an example. It should be interpreted as including meaning.

The encryption module 630 encrypts the data transmitted to the device at the request of the control module 620 as a module that performs encryption, or decrypts the data received after being encrypted from the device. The encryption module 630 may perform not only a public key encryption method but also a secret key encryption method, and one or more encryption modules may exist to perform both methods.

In particular, the rights objects are stored in an encrypted state, and the portable storage device 600 may encrypt the rights objects using a unique encryption key that cannot be read by other devices through the encryption module 630. In addition, when the right object is moved or copied to another device, or when another device requires permission to use a specific content, the encrypted right object can be decrypted using a unique encryption key. A symmetric key encryption method using a unique encryption key may be used to encrypt the rights object. In addition, it is possible to encrypt with a private key of the portable storage device 600 and to decrypt it with a public key of the portable storage device 600 when necessary. Do.

The storage module 640 stores encrypted contents, rights objects, certificates, CRLs, and the like of the portable storage device 600.

The control module 620 may control a mutual authentication process with the device when the portable storage device 600 is connected with the device. In addition, the controller may determine whether generation of the CPSF is necessary and instruct the data format generation module 650 to generate the CPSF. In this case, when the generation of the CPSF is required, as described with reference to FIG. 14, when the permission information of the specific rights object is requested from the device, when the playback of the specific content is requested from the device, and the specific rights stored in the portable storage device. It may be the case that the update request to update the object in the device.

When the data format generation module 650 is instructed to generate a CPSF from the control module 620, the data format generation module 650 searches for a right object for generating a CPSF, and generates a CPSF corresponding to the type of the retrieved right object. Such CPSF is as described with reference to FIGS. 7 to 13.

16 is a functional block diagram showing the configuration of a device according to an embodiment of the present invention.

In order to perform the DRM, the device 700 communicates with a content provider or a rights object issuing agency, a function for storing security functions and contents, a rights object, its own certificate and a CRL, and data exchange with a multimedia card. There should be data transmission / reception function and DRM management function. To this end, the device 700 includes an encryption module 730 having a security function, a storage module 740 having a storage function, an interface 710 for enabling data exchange with a portable storage device, and each component for performing DRM. It includes a control module 720 for controlling the module. Device 700 also includes a transmit / receive module 750 for data transceiving functionality and a display module 760 for displaying playbacks or executions of content.

The transmit / receive module 750 enables the device 700 to communicate with the content publisher or the rights object issuer by wire or wirelessly. The device 700 may obtain a rights object or encrypted content from the outside through the transmission / reception module 750, and may obtain a certificate or a CRL through communication with a certification authority.

The interface 710 allows the device 700 to be connected with the portable storage device. Basically, when the device 700 is connected to the portable storage device, the portable storage device and the interface of the device are electrically connected to each other. However, this is an example, and the connection means that the device 700 can communicate with each other through a wireless medium in a contactless state. It should also be interpreted as including the meaning of being in a state.

The encryption module 730 performs encryption and encrypts data transmitted to the portable storage device at the request of the control module 720, or decrypts data received by being encrypted from the portable storage device. The encryption module 730 may perform not only a public key encryption method but also a secret key encryption method and one or more encryption modules may exist to perform both methods.

In particular, the rights objects are stored in an encrypted state, and the device 700 may encrypt the rights objects using a unique encryption key that cannot be read by other devices or portable storage devices through the encryption module 730. It can also be decrypted using a unique encryption key when attempting to move or copy the rights object to another device or portable storage device. A symmetric key encryption method using a unique encryption key may be used to encrypt the rights object. In addition, the right object may be encrypted using the private key of the device 700 and decrypted with the public key of the device 700 when necessary.

The storage module 740 stores the encrypted content and rights objects and the certificate and CRL of the device 700.

The control module 720 may control a mutual authentication process with the portable storage device when the device 700 is connected to the portable storage device. Also, the control module 720 requests the portable storage device for permission information of the specific rights object as described with reference to FIG. 14, requests playback of specific content, or stores the specific rights object stored in the portable storage device. Request an update at 700). When the CPSF data as described above is received from the portable storage device in response to the request, the control module 720 interprets the received CPSF to obtain the content encryption key of the rights object or to obtain permission information of the rights object. Can be.

The display module 760 displays the playing state of the content that is allowed to be played through the rights object so that the user can visually see it. The display module 760 may be implemented with a liquid crystal display such as a TFT LCD or an organic EL.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

610, 710; Interfaces 620, 720; Control module
630, 730; Encryption modules 640, 740; Storage module
650; Data format generation module 750; Transceiver module
760; Display module

Claims (1)

The portable storage device receives a request from the device;
Generating a current permission status format that includes information about the rights object specified in response to the request; And
And transmitting the generated current permission status format to the device.

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