KR101396830B1 - Method for license management in a contents-sharing user domain - Google Patents

Abstract

The present invention relates to a method of managing licenses in a user domain that shares contents, and a license management method according to the present invention is a method of managing licenses in a user domain that shares content with each other by assigning license tokens to any one of the devices, , The status information of the license is updated in response to the content reproduction, and the license of the content is managed dynamically without a security vulnerability, and efficient content sharing among users is possible.

Description

How to manage licenses in a user domain that shares content {Method for license management in a content-sharing user domain}

1 is a diagram illustrating an apparatus for managing a DRM license including state information in a conventional user domain.

FIG. 2 is a flowchart of a method of managing a license by assigning a license token in a user domain that shares contents according to an exemplary embodiment of the present invention.

FIG. 3 illustrates a method of copying content and licenses in a user domain that shares contents according to an exemplary embodiment of the present invention. Referring to FIG.

4 is a diagram illustrating a method of reproducing contents in a user domain that shares contents according to another embodiment of the present invention.

5A to 5D illustrate a method of separating a device in a user domain that shares contents according to another embodiment of the present invention.

6A and 6B illustrate a method of controlling a device error in a user domain sharing content according to another embodiment of the present invention.

The present invention relates to a method of managing licenses in a user domain that shares content, and more particularly, to a method of managing licenses in a user domain that shares contents with a license token to a device having an authority to use the content, And a method of managing licenses of contents by constructing a token tree.

The growth of the Internet and the development of multimedia technology are facilitating the process of distributing and acquiring digital contents. Digital rights management (DRM), which emerged as a result, collectively refers to technologies and services that include the secure distribution and diffusion of content and content control based on policies in order to protect the rights of content owners and to prevent unauthorized use of digital contents It is a term.

Most of the DRM products that are currently commercialized are allowed to be used only by a specific device when the user purchases the digital content, and content mobility to other devices is not permitted. However, recently, social awareness of the use of content through the guarantee of private reproduction of digital contents has been gradually expanded, and DRM has been actively researched to support it. Domain Rights Management aims to support DRM so that it is possible to freely transfer and edit contents only for the equipment where private reproduction right is permitted.

 1 is a diagram illustrating an apparatus for managing a DRM license including state information in a conventional user domain. 1 includes a PC 101 in which a specific software for generating a license is installed in a predetermined group 105, a device A 102 storing a DRM license for a domain connected to the PC, A device B 103, and a device C 104.

Conventionally, a procedure for using DRM-protected contents in a predetermined group is as follows. In FIG. 1, it is assumed that DRM licenses available for N times are stored in the device A (102). Device B 103 requests a DRM license to use the content. And inputs a specific reproduction count K to be used by the device B 103 using the UI of the S / W stored in the PC 101. [ The specific reproduction count K should be smaller than N. [ Then, the PC 101 newly generates a DRM license capable of K times of reproduction and a DRM license capable of N-K times of reproduction. The PC 101 deletes the DRM license that can be reproduced N times, which is stored in the device A 102, and transmits the newly generated DRK license that can be reproduced N times. Further, the DRM license that can be reproduced K times is transmitted to the device B (103).

In such a conventional environment, a PC and an S / W for generating and updating a DRM license are required. The process of generating a license at the user level necessarily has a security vulnerability, and arbitrary modification of digital contents and rights is prohibited It is against the basic DRM policy. In addition, there is an inconvenience in that a user must specify the number of times of reproduction in advance in order to use the contents in another device, and the number of times of reproduction is not dynamically managed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to overcome the disadvantages of manually managing the number of times of reproduction for each device in order to use a content license in the above- In order to allow the users belonging to the same group to store the status information capable of dynamically managing the number of reproducible times in the license of the content and tokens for the usage right of the contents, And to provide a method of managing licenses of content that is efficiently shared.

According to another aspect of the present invention, there is provided a method of managing content licenses in a user domain that shares content, the method comprising: providing a license token to one of the devices; Reproducing the content by a device to which the license token is attached; And updating the status information of the license in correspondence with the reproduction of the content.

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

FIG. 2 is a flowchart of a method for assigning license tokens in a user domain that shares contents to manage licenses according to an embodiment of the present invention, including the following steps.

In step 201, a license token is assigned to any one of the devices. A license token is an identifier indicating a content usage right for devices belonging to the user domain to share and use one content.

In step 202, the device to which the license token is assigned plays the content. As described above, the license token means the usage right of the content, so that the license token is monopolized by one device, and when the other device wants to reproduce the content, the license token must be received. This will be described in detail later.

In step 203, the license status information is updated in response to the content reproduction. The license status information may include various information including the number of reproducible times, and may be information that can change according to the reproduction of the content. I will explain it again later.

Hereinafter, the embodiments of the present invention will be described with a tree structure called a token tree using the license token.

In general, a tree structure is a tree structure in which a root node located at a vertex, a child node connected to a root node, a child node of a child node connected to a child node Node). ≪ / RTI > When the nodes are connected to each other in the tree structure, a node located near the root node is generally referred to as a parent node, and a node located opposite to the direction of the root node is referred to as a child node. In addition, it is common that each node stores a path for a parent node and a child node from itself in order to express the connection relationship.

A token tree is constructed by adding the remaining devices except the device set as the root node as a child node of the tree. The remaining devices may be added as a root node of a tree or as a child node of a member node other than a root node. Each of the nodes is connected to a parent node And the path to the child node.

The token tree has a feature that a root node has a license token and that if a certain node in the token tree follows a path to a parent node connected to the node, a license token meaning a usage right for the content can be obtained I have. That is, a specific device in the user domain may search for and request a path to a parent node connected by one node from the current node of the configured token tree to use the content.

FIG. 3 illustrates a method of copying content and licenses in a user domain that shares contents according to an exemplary embodiment of the present invention. Referring to FIG.

3, a circle 301 represents a node representing five devices of N1, N2, N3, N4, and N5, a small circle 302 displayed on the device N1 represents a license token, The small rectangle 303 shows the number of reproducible times K of the contents. A circle 304 represented by a dotted line enclosing all of the nodes means a user domain that shares contents. The device included in the group is allowed to reproduce or copy the content.

Each node is connected to an IP network or the like, and it is desirable to have a unique address or identification path. In FIG. 3, it is assumed that the device N1 is a node having usage right for contents. As described with reference to FIG. 2, the license token 302 is assigned to a node having a usage right for the content, and is set as a root node of the token tree. In addition, the number of reproducible times is stored and managed as license status information.

Referring to FIG. 3, the process of copying contents and licenses according to the present invention is as follows. First, when the device N1 downloads content available for K times, the license for the content is stored in the device N1, and a license token for the license is generated and stored. When the device N3 requests content sharing to the device N1, the content and the license are copied (311). The device N3, in addition to the license copying process, updates N1 from the current node to the path to the parent node as a path to the license token, and stores the playable number K of the content. The path may be specified by a predetermined IP address or URL for the device N1. In FIG. 3, the content copying process 311 from the device N1 to N3 is shown by a dotted line, corresponding to the solid line from the device N3 to N1 as a path to the parent node of the device N3.

The contents can be copied 312 from the device N5 to the N1 and the content 313 can be copied from the device N4 to the N5 in the same manner as described above.

4 is a diagram illustrating a method of reproducing contents in a user domain that shares contents according to another embodiment of the present invention. In FIG. 4, it is assumed that the device N1 is the root node having the license token, and the device N3 requests the reproduction of the content.

First, the device N3 checks whether the node itself has a license token for the content before reproducing the content. In FIG. 4, since the device N3 does not have a license token, it is not authorized to reproduce the content. Therefore, the device N1 is searched using the path from the node N3 to the parent node. Since the search result N1 is the root node having the license token, after acquiring the license token from the device N1, the content is reproduced to the extent that the number of times the content can be reproduced is 1 or more. If the number of times of content reproduction is one, the number of reproducible times for the content will be updated K-1 times in the conventional K times.

The process of acquiring the license token from the root node may include transmitting the license token from the root node to the child node and transmitting a path to the parent node of the root node that transmitted the license token to the root node, And resetting the child node to the root node of the token tree. 4, the license token is transferred from the root node N1 to the child node N3 (401), and the device N3 is reset to the root node by updating the path to the parent node of N1 to the path from N1 to N3 (402) do.

Through the process of resetting the root node as described above, the rule that the license token can always be found by searching for the path to the parent node from the current node as described in FIG. 2 is satisfied. 4, the parent node N5 is checked in the device N4, and since the license token can not be found in the device N5, the parent nodes N1 and N3 of the node N5 are checked in order, License token can be found in N3.

5A to 5D illustrate a method of separating a device in a user domain that shares contents according to another embodiment of the present invention. The method of separating a device from a node included in a token tree, that is, a user domain, can be largely divided into two cases depending on how many objects are to be separated.

First, in order to separate the device from the user domain, the device may be divided into three cases according to whether a node to be deleted corresponds to a position of the token tree in order to maintain the structure of the token tree.

(a1) If the node corresponding to the device to be separated is a leaf node of the token tree, the corresponding node may be deleted.

In FIG. 5A, when the device to be removed is N5 (510), since it corresponds to a leaf node, only the corresponding node can be deleted.

(a2) If the node corresponding to the device to be separated is a root node of the token tree, the license token is transmitted to any first child node of its child nodes, Resetting the route to the root node, updating the route to the parent node of the remaining child nodes other than the first child node to the route to the first child node, and then deleting the route. That is, make any child node the root node of the token tree.

5B, when the device to be separated is N1 520, since it corresponds to the root node, N2 521 is selected as an arbitrary child node among the child nodes N2, N3 and N5 of N1 520, And sets the N2 522 and the parent node of the N5 523 as a route to the N2 521, and then deletes N1 .

(a3) If the node corresponding to the device to be separated is an internal node that is not a leaf node or a root node of the token tree, a path to a parent node of its child nodes is a path to its parent node And deletes itself. That is, it connects its child nodes directly to its parent node.

5C, the path to the parent node of N4 531, which is the child node of N5 530, is the path to the parent node N1 of N5 530, And deletes N5 (530).

Second, when attempting to separate all of the devices from the user domain, the following two methods may be preferred.

(b1) It is possible to repeat the process (a1 to a3) of separating one device by the number of devices, but the efficiency will be lower than the method described below.

(b2) transmitting a predetermined tree decommissioning command from the root node of the token tree to the child node, and repeating the process of removing the tree tree until all the nodes of the token tree are separated. This may be implemented in a form similar to the recursive method of a so-called computer algorithm.

In FIG. 5D, the node N1, which is the root node, transmits a tree decomposition command to each of the child nodes N2, N3, and N5, and deletes its own node N1. In the next step, since the nodes N2 and N3 of the child nodes receiving the tree disassembly command are leaf nodes, the disassembly procedure is terminated by deleting the node, and the above procedure is repeated in the node N5. In other words, the disassembly procedure of all the token trees is completed by transmitting the tree disassembly command to the node N4, which is a child node of the node N5, and deleting the tree disassembly command.

Meanwhile, using the disassembly procedure of the token tree and the license token transmission process in the content reproduction process, a token tree disassembly process for playing the content in an offline environment can be implemented.

In this case, it is assumed that content desired to be played back is stored in a specific device among the devices included in the content sharing group, and it is desired to carry it out and use it. That is, a process of transmitting content to a target device to be separated will be necessary, and a process of separating the device from the user domain connected to a predetermined network will be required. In this process, the copying process of the license token necessary for reproducing the contents described in FIG. 4 may be utilized, and the process of separating all the modes of the token tree described in FIG. 5D may be utilized.

6A and 6B illustrate a method of controlling a device error in a user domain sharing content according to another embodiment of the present invention. Here, it is assumed that an error occurs in the token tree information due to a device failure or the like, and the license can not be normally managed. Also assume that the failed device can not provide a license token or path information for parent and child nodes.

If an error occurs in some of the devices, a step of finding a node corresponding to the failed device is preceded by using the path information of the parent node at an arbitrary node of the token tree.

It is preferable that a step of transmitting a root node search command through multicasting is performed when an error occurrence device is found along the path of the parent node. The multicasting refers to a method of transmitting data in a manner that a plurality of devices are targeted at one device on the network in order to search for a specific device. If there is no error in the root node through this process, it will reply that it is operating normally.

If the error generating device corresponds to a root node, regenerates the license token from the minimum number of reproducible times stored in the other node except for the root node and resets the node to the root node, The route to the parent node of the child nodes of the error generating device is updated to the root node.

6A assumes that an error has occurred in the device N1 610, which is the root node, and no device responds by the multicasting. In this case, it may be desirable for the node that detected the device error to send a license token regeneration command to each node also in a multicast manner after a predetermined period of time that an error has occurred in the root node. Based on this, it is determined that the node having the minimum value has the latest license status information, and the license token is regenerated based on the minimum number of renewable times do. In FIG. 6A, the device N2 611 has a minimum value of K-1, and regulates the error by regenerating and storing the license token in N2 and reconfiguring the token tree as the root node.

6B is a case where an error occurs in the device N5 620 which is not the root node. When the device N1 which is the root node responds by the multicasting, the device N4 621 which has found the error, The error is controlled by updating the path with the path to the root node.

The preferred embodiments of the present invention have been described above. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

In order to overcome the inconvenience of manually managing the number of playbacks for each device and the vulnerability to divide or regenerate the content license in order to use the license of the content in the conventional user domain, Storing license information of licenses of licenses of contents, storing state information capable of dynamically managing the number of reproducible times of licenses of contents, and assigning license tokens for use rights of contents, thereby dynamically managing licenses of contents without security weaknesses, To provide a license management method.

Further, in addition to a management method for reproducing contents protected by a license, a license management method for separating a specific device belonging to a user domain or separating all of the devices so as to be reproducible offline can be provided.

Claims (5)

A method for managing licenses of content shared by devices belonging to any one of the domains, Setting a device to which a license token is attached and a device to which the license token is attached to a device that downloaded the content among the devices as a root node; When the device that is not set as the root node requests the content, the content is copied from the device set as the root node to the device that requested the content; Updating the device set as the root node to a parent node; And The device to which the content is copied is updated to a root node, and the updated root node reproduces the content; ≪ / RTI > The method according to claim 1, Further comprising updating status information of the license, wherein updating the status information of the license includes subtracting the number of times of reproduction of the content. The method according to claim 1, Wherein the step of reproducing the content comprises: checking whether a device to reproduce the content has the license token; And Playing the content if the device has the license token and retrieving the device having the license token using the path to the parent node if the device does not have the license token and receiving the license token from the device, And updating the root node by updating the parent node with the child node that has received the license token. The method according to claim 1, When the device to be separated has the license token when it tries to separate the device from the domain, it transmits the license token to an arbitrary device connected to itself and separates itself from the domain, Separating the device according to any one of repeating the dividing process as many times as the number of devices or sending a predetermined batch separation command for dividing all the devices belonging to the domain Way. The method according to claim 1, When an error occurs in some of the devices, Detecting the device in which the error occurred; Searching for a device having the license token; And If the error generating device has the license token, regenerating the license token from the license state information stored in the other device, and if the error generating device does not have the license token, separating the error generating device from the domain The error control step comprising:

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