BRIEF DESCRIPTION OF THE DRAWINGS
The above and other aspects of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
FIG. 1 is a conceptual diagram of license management according to an exemplary embodiment of the present invention;
FIG. 2 is a block diagram of an apparatus for managing a license according to an exemplary embodiment of the present invention;
FIG. 3 is a flowchart illustrating a method of managing a license according to an exemplary embodiment of the present invention; and
FIG. 4 is a flowchart illustrating a method of managing a license according to another exemplary embodiment of the present invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals denote like elements throughout the drawings.
FIG. 1 is a conceptual diagram of license management according to an exemplary embodiment of the present invention. License management includes three basic modes, which are a license addition mode, a license deletion mode, and a license search mode. The most basic mode is a search mode in which a first value corresponding to input license information is computed by performing a Hash function 102 using the license information as a Hash value 101 and a second value corresponding to the first value is selected from the Hash mapping table 103. Then, a tree structure 104 associated with the second value selected from the Hash mapping table 103 is selected, and a node corresponding to the license information is searched for using the license information as a key of the tree structure 104.
In general, the license information is information, such as the identification/identifier (ID) of a license file. When a user inputs to a device a request to execute content or perform an operation, the device first must interpret a license of the requested content.
It is possible to determine whether the user has a right to use the content, and extract information, such as key information for decrypting encrypted content, by interpreting the content license. The extracted information allows use of the content to be controlled according to the user's request. In order to execute the content, content license is first searched for and accessed. In order to achieve this, a device storing the license manages the license in the form of a database. In most related art methods, a license is managed by using a binary tree structure.
However, as use of large-capacity storage devices has become popular and the number of files or content to be stored and managed increases rapidly, the number of licenses to be managed accordingly also increases rapidly. For example, if 50,000 pieces of music content and licenses thereof are managed by using a binary tree structure, a node of a binary tree structure stores the location information of a license, that is, a node corresponds to only one license, when all of the licenses are constructed in the form of a group of binary tree structures. Assuming that a piece of pointer pointing to a corresponding license is 4 bytes long, apart from the license information, a storage space of 200 KB (50,000×4 bytes) is needed. Accordingly, a major part of the memory of a device must be allocated for the group of tree structures.
However, if a Hashing technique is used together with the binary tree structure, it is possible to reduce memory usage and increase the speed of computation. For example, as illustrated in FIG. 1, a license having an ID of 69 is searched for by computing a first value by performing the Hash function 102 with the ID 69 as a Hash value 101, selecting a second value corresponding to the first value from the Hash mapping table and selecting a tree structure associated with the second value. If a tree structure corresponding to the license ID is determined, a node associated with the second value is searched by using the License ID as the key of the tree structure. For example, as illustrated in FIG. 1, if the tree structure corresponding to license ID 69 is determined, 69 is compared with 74 at the first node of 74. Since 69 is smaller than 74, 69 is compared with 63 at a left node of 63. Then, because 69 is greater than 63 the node 105 is determined corresponding to the license. When a corresponding node is determined, it is possible to access the license, based on the location information the corresponding node contains.
As, described above, when the Hashing algorithm is used together with the tree structure, if 50,000 licenses are stored, the size of memory to be allocated is 50,000/100×4+100×4=2.4 KB in order to search for a license, assuming that a Hashing table is about 100 bytes long. When the Hashing algorithm is used together with the binary tree structure, only a tree structure associated with the second value is loaded into memory instead of the whole group of tree structures. In this case, the memory size used is 100 times smaller than when only a tree structure is used.
As described above, the amount of search time incurred is O(log N) when only a tree structure is used. On the other hand, when the Hashing algorithm is used together with the tree structure, if 50,000 licenses are stored, ideally, 500 (50,000/100) nodes are allocated to a tree structure, thereby requiring a total amount of search time is O(1)+O(log n), where n is 500. In general, since a tree structure is a balanced structure, even if random data is input by hashing, it is possible to always maintain stable depth. In an exemplary embodiment of the present invention, the ID of a license is used as license information, but any information allowing the license to be identified the license may be available as license information.
FIG. 2 is a block diagram of an apparatus for managing a license according to an exemplary embodiment of the present invention. The apparatus comprises a license detection unit 207, a license storage unit 208, and an interface unit 201. The license detection unit 207 comprises a controller 202, Hash function processor 203, and a Hash mapping table 204. The license storage unit 208 comprises a tree structure manager 205 and a license database (DB) 206. When a user requests content to be executed, a license corresponding to the content is requested and searched for in order to access the license. In this case, it is advantageous to use an interface unit 201 to deliver such information as the location information of the license, etc.
The apparatus of FIG. 2 for detecting the location of a license from license information may be embodied within a central processing unit (CPU) of a system. When license information is input to the apparatus, a Hash function processor 203 computes a first value by performing a Hash function with the input license information as a Hash value. Then, a controller 202 searches a Hash mapping table 204 for a second value corresponding to the first value, and selects a tree structure corresponding to the second value. When the tree structure is selected, a tree structure manager 205 selects a corresponding node by using the license information as a key of the tree structure. A license corresponding to the license information is obtained from a license database (DB) 206 by using the location information contained in the corresponding node.
FIG. 3 is a flowchart illustrating a method of searching for a license according to an exemplary embodiment of the present invention. When information of a license that is to be searched for is input (Operation 301), a Hash function is performed using the license information to compute a first value (Operation 302). A second value mapped to the first value is selected from the Hash mapping table, and a tree structure associated with the second value is selected (Operation 303). A node corresponding to the license information is selected from the tree structure by using the license information as a key of the tree structure (Operation 304), and a license corresponding to the license information is searched for by using the location information contained in the node (Operation 305).
FIG. 4 is a flowchart illustrating a method of adding a license according to another exemplary embodiment of the present invention. First, a Hash function is performed using the information of license that is to be added (Operation 401), and then, it is determined whether a tree structure corresponding to the result of performing the Hash function is present (Operation 402). If it is determined that a corresponding tree structure is present, a node corresponding to the license information is added to the tree structure corresponding to the license information (Operation 403). If it is determined that a corresponding tree structure is not present, a tree structure corresponding to the result of performing the Hash function is newly generated (Operation 404), and a node corresponding to the license information is added to the newly generated tree structure (Operation 403).
A process of deleting a license may be performed in a similar way in which the process of searching a license is performed. That is, a node corresponding to the information of license that is to be deleted is searched for according to the method of FIG. 3, and the searched node is then deleted.
The present inventive concept can be embodied as computer readable code in a computer readable medium. The computer readable medium may be any recording apparatus capable of storing data that is read by a computer system, e.g., a read-only memory (ROM), a random access memory (RAM), a compact disc (CD)-ROM, a magnetic tape, a floppy disk, an optical data storage device, and so on. Also, the computer readable medium may be a carrier wave that transmits data via the Internet, for example. The computer readable medium can be distributed among computer systems that are interconnected through a network, and the present invention may be stored and implemented as computer readable code in a distributed system.
According to a method and apparatus for managing a license, it is possible to effectively use limited resources of a device, and quickly search for, add, or delete a license while minimizing memory usage.
While this inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill 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.
Patent Application
20080027870
