Abstract: A method of managing a home network key in a home network environment, which has a key management server for managing the home network key and a plurality of home network devices, includes: allowing a home network device to generate device unique information and to transmit the device unique information to the key management server; allowing the key management server to generate a parameter for generating the home network key by using the device unique information and to transmit the parameter to the home network device; and allowing the home network device to generate the home network key by using the parameter. The generated home network key being independent of the device unique information.

Abstract: A scrambling apparatus and method are provided for increasing randomness without damaging compression efficiency of total video data by selectively and randomly performing conversion when converting motion vector codes of compressed video data into other motion vector codes indicating other motion vector values, and more particularly, by performing conditional conversion only if a predetermined condition is satisfied when selective conversion of motion vector codes is performed. The scrambling apparatus includes a conversion motion vector code table generator generating a conversion motion vector code table comprising motion vector codes obtained by converting motion vector codes corresponding to motion vector values of input video data in a standard motion vector code table; and a conversion controller randomly determining whether a certain motion vector value is encoded using the conversion motion vector code table or the standard motion vector code table.

Abstract: Provided are a method and apparatus for managing a digital rights management (DRM) module. A DRM module for removing a DRM scheme applied to a content selected from among contents, and the content being protected with the DRM scheme, are received. The content is used by using the DRM module, and then the DRM module is partially or completely removed.

Abstract: Provided are a method and apparatus for controlling transmission of content data. In the method, a communication channel is initially established to transmit the content data, the content data is transmitted through the established communication channel, verification is performed a plurality of times to determine whether the content data is transmitted within an acceptable transmission range, and whether to continue the transmission of the content data is determined according to the verification result. Accordingly, when a client moves to a location outside a predetermined acceptable transmission range in a wireless environment, a server stops transmission of the content data. In addition, content data can be continuously transmitted regardless of interference caused by a temporary obstacle between a server and a client.

Abstract: A method of encrypting data is provided. The method includes dividing data in packet units into N data blocks; generating an initial counter value using a random number used for generating an encryption key for encrypting the data blocks; generating N counter values by increasing the initial value by a predetermined value N times and encrypting the N counter values using the encryption key; and performing an exclusive OR operation on the N encrypted counter values and the N data blocks.

Abstract: A method and apparatus for preventing modulation of an executable program are provided. The method includes decoding a header of the executable program and generating information about a plurality of executable codes, grouping the plurality of executable codes into a first code group and a second code group with reference to the information about the plurality of executable codes, matching each of the plurality of executable codes included in the first code group with each of the plurality of executable codes included in the second code group, and encoding each of the corresponding executable codes included in the second code group using each hash value of the executable codes included in the first code group.

Abstract: A method and apparatus for effectively managing a plurality of licenses are provided. The method includes selecting a value, which corresponds to license information, from a Hash mapping table; selecting a node corresponding to the license information from a tree structure corresponding to the value; and searching for a license by using license location information contained in the node. The apparatus includes a Hash function processor which computes a first value corresponding to the license information using a Hash function; a controller which selects a tree structure corresponding to the license information based on the first value computed by the Hash function processor; a tree structure manager which selects a node corresponding to the license information from the tree structure; and a storage unit which stores the license.

Abstract: A method of managing a home network key in a home network environment, which has a key management server for managing the home network key and a plurality of home network devices, includes: allowing a home network device to generate device unique information and to transmit the device unique information to the key management server; allowing the key management server to generate a parameter for generating the home network key by using the device unique information and to transmit the parameter to the home network device; and allowing the home network device to generate the home network key by using the parameter. The generated home network key being independent of the device unique information.

Abstract: A multimedia device having a function of backing up received broadcasting contents in a home network environment and a method of backing up the broadcasting contents. The multimedia device includes a local storage unit for storing received broadcasting contents, and a storage controlling unit for controlling storage of the broadcasting contents. When a space of the local storage unit is insufficient or when a user requests a backup, the storage controlling unit controls the device to transfer some of the stored broadcasting contents to a backup device. Accordingly, the multimedia device backs up the received broadcasting contents in various backup devices, thereby efficiently controlling the storage space of the local storage unit. Also, the multimedia device can prevent the backed-up contents from being arbitrarily reproduced or copied by another unauthorized multimedia device.

Abstract: A bidding method including: (a) generating a first bidding function value using an initial bidding price of a first bidder; (b) transmitting the first bidding function value to a successful bidding decider; (c) transmitting a second bidding function value of a second bidder to the first bidder; (d) transmitting a final bidding price of the first bidder and a final bidding price of the second bidder to the successful bidding decider; (e) determining a successful bidding price by comparing the final bidding price of the first bidder and the final bidding price of the second bidder; and (f) verifying whether or not the successful bidding price was manipulated

Abstract: A watermarking apparatus for embedding a watermark in a digital image, an apparatus for extracting watermark information from a watermarked image using a public key having a plurality of secret keys, and an apparatus for identifying whether a watermarked image generated by embedding a watermark in each region using a unit secret key is a copy of contents. The watermarking apparatus includes: a watermark generating unit that divides the digital image into a plurality of regions, assigns predetermined secret keys to each of the divided regions, respectively, and generates a watermark for each of the divided regions using the corresponding secret key; and a watermark embedding unit that generates a watermarked image for the digital image by embedding the watermarks in the corresponding regions, respectively, and combines the watermark-embedded divided regions. Since different kinds of keys are used when watermarking and extracting watermarked information, the watermark can be protected from illegal attacks.

Abstract: A scrambling apparatus and method are provided for increasing randomness without damaging compression efficiency of total video data by selectively and randomly performing conversion when converting motion vector codes of compressed video data into other motion vector codes indicating other motion vector values, and more particularly, by performing conditional conversion only if a predetermined condition is satisfied when selective conversion of motion vector codes is performed. The scrambling apparatus includes a conversion motion vector code table generator generating a conversion motion vector code table comprising motion vector codes obtained by converting motion vector codes corresponding to motion vector values of input video data in a standard motion vector code table; and a conversion controller randomly determining whether a certain motion vector value is encoded using the conversion motion vector code table or the standard motion vector code table.