Abstract: A method of creating a domain based on public key cryptography includes providing, by a content-providing server, a list of devices requesting content, and selecting, by a user, a device from the list; transmitting, by the server, discrimination information on revoked devices to the device; extracting, by the device having received the discrimination information, a secret value from the discrimination information, preparing a certificate using the extracted secret value, and transmitting device information and the certificate of the device to the server; verifying, by the server, the certificate and creating a domain ID and a domain key using the device information; encrypting, by the server, the domain ID and the domain key using a unique public key of the device and transmitting the encrypted domain ID and domain key to the device; and restoring, by the device, the domain key using a unique secret key of the device.

Abstract: A texture description method in a frequency domain for extracting texture features by transforming and Gabor-filtering an input image into an image of the frequency domain, and a texture-based retrieval method thereof are provided. The texture description method in the frequency domain includes: a first step of transforming an image of a time domain into an image of the frequency domain; a second step of filtering the transformed image using a Gabor filter having N×M filter regions, where N and M are respective predetermined positive integers; a third step of extracting feature values of the image that has been Gabor-filtered in respective channels of the frequency domain division layout corresponding to the N×M filter regions of the Gabor filter; and a fourth step of deciding a texture descriptor of the image on the basis of the feature values of the image.

Abstract: A color image processing method for retrieving a color feature descriptor for describing color features of an image is provided. The color image processing method includes the steps of (a) obtaining color vectors of an input image, (b) classifying the color vectors to obtain dominant colors of the input image and the ratios thereof, and (c) representing the dominant colors and the ratios thereof as a color feature descriptor of the input image. The color image processing method is applied to an object-based image processing method, thereby allowing fast search and retrieval of multi-media contents.

Abstract: A digital image texture analyzing method including the steps of (a) obtaining the mean (?0) and variance (?0) of the pixel values of an original image, and (b) obtaining m×n filtered images by filtering the original image using predetermined filters, each having a unique combination of one of m scales and one of n orientations, where m and n are predetermined positive integers, (c) calculating the means (?11, ?21, . . . , ?mn) and variances (?11, ?21, . . . , ?mn) of the respective filtered images, and (d) obtaining a texture descriptor having the mean (?0) and variance (?0) of the pixel values of the original image obtained in the step (a), and the means (?11, ?21, . . . , ?mn) and variances (?11, ?21, . . . , ?mn) of the respective filtered images obtained in the step (c), as texture features. The texture analyzing method allows image textures to be more accurately analyzed and compared.

Abstract: Disclosed is a domain authentication method for exchanging content between devices. The domain authentication method for exchanging content between devices according to the present invention includes a first step of setting domain identification information into a predetermined device connected on a wired/wireless network; a second step of generating a domain secret key using the set domain identification information and predetermined device identification information; a third step of generating a predetermined first code value and transmitting a first packet encrypted with the first code value using the domain secret key generated in the second step; a fourth step of receiving a second packet that is encrypted with the first code value and a second code value; and a fifth step of decrypting the second packet received in the fourth step.

Abstract: A system for preventing copying of audio/video (AV) data, including a copy control information inspection unit receiving first copy control information from AV data including an AV content information section having the first copy control information and an AV content section having second copy control information, and transmitting the first copy control information and a control command corresponding to the first copy control information, a key generation unit generating a decryption key using the first copy control information and predetermined information for the decryption key generation, according to the control command, and a decryption unit decrypting the AV data with the use of the decryption key.

Abstract: An AV stream processing system includes an AV stream input unit which receives an AV stream having an AV content information field including first copy control information, and an AV content field including second copy control information, a determination unit which extracts the first and second copy control information from the received AV stream and determines whether the first copy control information has been modified, and an AV stream decryption unit which processes the received AV stream according to predetermined criteria, when the first copy control information has been modified.

Abstract: An AV stream processing system includes an AV stream input unit which receives an AV stream having an AV content information field including first copy control information, and an AV content field including second copy control information, a determination unit which extracts the first and second copy control information from the received AV stream and determines whether the first copy control information has been modified, and an AV stream decryption unit which processes the received AV stream according to predetermined criteria, when the first copy control information has been modified.

Abstract: A method of establishing a home domain capable of reproducing multimedia content, and a smart card therefor. The method includes creating a domain certificate for a reproducing device by inserting the smart card into the reproducing device, creating a session key by inserting the smart card into a home server, and verifying the domain certificate of the reproducing device and transmitting the created session key to the reproducing device if the device is a legitimate device. Alternatively, the method includes using an external certificate authority to determine whether the reproducing device is a legitimate device.

Abstract: The present invention relates to an apparatus and system for data copy protection, and a method thereof. The present invention provides a transmitting apparatus for setting control information for data copy protection, encrypting data by using different encryption processes according to respective control modes corresponding to the set control information, and transmitting the encrypted data; a receiving apparatus for receiving the transmitted encrypted data, extracting the control information from the received data, and decrypting the encrypted data by using different decryption processes according to respective control modes corresponding to the extracted control information; and a system having the transmitting apparatus and the receiving apparatus.

Abstract: A system for authenticating a content user, comprising a group common key that authenticates a user, a private key owned by the user, a trusted organization adapted to create and distribute the group common key, and to store personal information on the authenticated user and a temporary registration certificate issued to the authenticated user. A user apparatus converts the temporary registration certificate by means of a predetermined conversion method using the private key, and further provides the converted temporary registration certificate to a content provider prior to executing content provided by the content provider the content provider adapted to check whether the user has been authenticated by the trusted organization, using the group common key prior to providing the content.

Abstract: A method for retrieving an image texture descriptor for describing texture features of an image, including the steps of (a) filtering input images using predetermined filters having different orientation coefficients, (b) projecting the filtered images onto axes of each predetermined direction to obtain data groups consisting of averages of each directional pixel values, (c) selecting candidate data groups among the data groups by a predetermined classification method, (d) determining a plurality of indicators based on orientation coefficients of the filters used in filtering the candidate data groups, and (e) determining the plurality of indicators as the texture descriptor of the image. The texture descriptors which allow kinds of texture structure present in an image to be perceptually captured can be retrieved.

Abstract: A method of encrypting metadata that can be represented by a tree structure. The method involves generating an encryption key for a predetermined node of the metadata using a function that takes as input parameters an encryption key for an upper node of the predetermined node and information specifying the predetermined node, and encrypting data of the predetermined node using the generated encryption key.

Abstract: A color image processing method for retrieving a color feature descriptor for describing color features of an image is provided. The color image processing method includes the steps of (a) obtaining color vectors of an input image, (b) classifying the color vectors to obtain dominant colors of the input image and the ratios thereof, and (c) representing the dominant colors and the ratios thereof as a color feature descriptor of the input image. The color image processing method is applied to an object-based image processing method, thereby allowing fast search and retrieval of multi-media contents.

Abstract: A technique for encrypting an audio and/or video (A/V) stream, and more particularly, an apparatus and method for encrypting an A/V stream, and an apparatus and method for generating a random number necessary for generating an encryption key used in encrypting an A/V stream are disclosed. The apparatus includes a content processor, a random number generator, an encryption key generator, and a content encryptor. The content processor receives an audio/video stream, performs a predetermined processing operation on the audio/video stream, and generates and outputs predetermined data to be used for generating a random number. The random number generator receives the predetermined data from the content processor and generates the random number. The encryption key generator receives information comprising the random number and generates an encryption key using the information. The content encryptor encrypts the audio/video stream output from the content processor using the encryption key.

Abstract: An apparatus and method to encrypt data having hierarchical information are provided. The apparatus includes an N-th layer key generator, which generates an N-th layer key, an (N+1)-th layer key generator, which generates an (N+1)-th layer key by applying the N-th layer key to a predetermined function, an N-th layer data encryptor, which encrypts N-th layer data using the N-th layer key, and an (N+1)-th layer data encryptor, which encrypts (N+1)-th layer data using the (N+1)-th layer key.

Abstract: A method of indexing a high-dimensional vector space, along with a method of quickly retrieving a feature vector having features similar to a query vector from the vector space indexed by the indexing method, are provided. The method of indexing a feature vector space includes the steps of (a) partitioning the feature vector space into a plurality of approximation regions; (b) selecting an arbitrary approximation region to determine whether the selected approximation region is heavily or sparsely distributed; and (c) if the approximation region is determined to be sparsely distributed, indexing the corresponding approximation region as one special node belonging to a child node of the tree data structure, together with any other sparsely distributed approximation region spaced apart by a distance less than a predetermined distance.

Abstract: A method of indexing a high-dimensional vector space, along with a method of quickly retrieving a feature vector having features similar to a query vector from the vector space indexed by the indexing method, are provided. The method of indexing a feature vector space includes the steps of (a) partitioning the feature vector space into a plurality of approximation regions; (b) selecting an arbitrary approximation region to determine whether the selected approximation region is heavily or sparsely distributed; and (c) if the approximation region is determined to be sparsely distributed, indexing the corresponding approximation region as one special node belonging to a child node of the tree data structure, together with any other sparsely distributed approximation region spaced apart by a distance less than a predetermined distance.

Abstract: A digital video processing method and an apparatus thereof are provided. The method for processing digital images received in the form of compressed video streams comprising the step of determining a region intensity histogram (RIH) based on information on motion compensation of inter frames. The RIH information is obtained based on the motion compensation values of inter frames, and the RIH information is a good indicator of motion information of a video scene. Also, since the RIH information is quite a good indicator of intensity of the video scene, video streams having similar intensities can be effectively searched by searching for similar video scenes based on the RIH information obtained by the digital video processing method.

Abstract: A digital video processing method and an apparatus thereof are provided. The method for processing digital images received in the form of compressed video streams comprising the step of determining a region intensity histogram (RIH) based on information on motion compensation of inter frames. The RIH information is obtained based on the motion compensation values of inter frames, and the RIH information is a good indicator of motion information of a video scene. Also, since the RIH information is quite a good indicator of intensity of the video scene, video streams having similar intensities can be effectively searched by searching for similar video scenes based on the RIH information obtained by the digital video processing method.