Abstract: A method of backing up domain information relating to the construction of a domain is provided. In the method, the domain information is encrypted and the encrypted domain information is stored in a predetermined storage device in the domain the encrypted domain information to the predetermined storage device, thereby securely backing up the domain information without the help of an external network. Accordingly, even when the existing domain server malfunctions, a new domain server is capable of obtaining the domain information.

Abstract: A method of measuring round trip time (RTT) includes: chain-hashing at least one random number to create a plurality of hash values; (b) transmitting one of the created hash values to a device and starting to measure RTT of the device; and (c) receiving from the device a response to the transmitted hash value and ending the RTT measurement, thereby performing a more effective proximity check than a conventional proximity check requiring encryptions and decryptions of several tens of times through several thousands of times.

Abstract: A method of managing and restoring an identifier of a storage device and an apparatus therefor are provided. The method includes the operations of generating a storage device identifier; recording the storage device identifier in a non-volatile memory of a host; generating an identifier file including the storage device identifier and a host identifier; and recording the identifier file in the storage device. By doing so, the method and apparatus can efficiently and securely manage the storage device.

Abstract: A method and apparatus for encrypting or decrypting digital content are provided. In the method, a binding range is selected from a plurality of binding ranges of content use based on license information of the content, and the content is encrypted based on the selected binding range so that the content can be used only within the selected binding range. Accordingly, it is possible to limit content use to a plurality of binding ranges of use of the content, using license information of the content.

Abstract: A method and apparatus for protecting digital content in a digital rights management (DRM) system are provided. The method includes: determining a usage rule for content included in a first content file based on usage constraint information included in the first content file; and generating a second content file complying with this usage rule. According to the method and apparatus, the security requirement of content creators and content providers can be satisfied and at the same time the requirement of content consumers for freer usage can be satisfied.

Abstract: A method and an apparatus for managing domains are provided. The method of managing one or more domains performed by a domain manager located in a home network includes determining whether to register a first device located in the home network to a domain, and providing data required to share content between the first device and a second device registered to the domain according to the determination. In the method and apparatus, content can be shared by connecting the devices with one another including a user, and the burden of content providers for management can be reduced.

Abstract: A method and an apparatus for managing domains are provided. The method of managing one or more domains performed by a domain manager located in a home network includes determining whether to register a first device located in the home network to a domain, and providing data required to share content between the first device and a second device registered to the domain according to the determination. In the method and apparatus, content can be shared by connecting the devices with one another including a user, and the burden of content providers for management can be reduced.

Abstract: A method and apparatus for protecting digital content in a digital rights management (DRM) system are provided. The method includes: determining a usage rule for content included in a first content file based on usage constraint information included in the first content file; and generating a second content file complying with this usage rule. According to the method and apparatus, the security requirement of content creators and content providers can be satisfied and at the same time the requirement of content consumers for freer usage can be satisfied.

Abstract: A method of receiving a session key in a home network and a method of reproducing content using the same. The method of receiving a session key from a home server in a home network, includes: (a) whenever one of members of the home network changes, receiving and storing the session key and a session version indicating a session key generation sequence; (b) receiving a license necessary for reproducing predetermined content; and (c) determining a session key necessary for reproducing the predetermined content based on an encoding session version (ESV), which is a session version extracted from the license, and the stored session version. A home server transmits a session key and a session version to a user device whenever a subscriber to a home network changes, and the user device determines a session key using the session version, thereby performing a variety of domain administration by freely transmitting content between user devices.

Abstract: A method and apparatus for protecting digital content in a digital rights management (DRM) system are provided. The method of importing a first content file into a second content file includes determining a usage rule of content included in the first content file based on information used to control remote access of the content included in the first content file; and generating the second content file that follows the determined usage rule.

Abstract: A method of measuring round trip time (RTT) and a proximity checking method using the same. The method of measuring RTT includes: transmitting a hashed second random number and starting the RTT measurement; and receiving a hashed first random number from a device that received the hashed second random number and ending the RTT measurement, thereby greatly reducing repetitive encryption and decryption operations in the proximity check using a repetitive RTT measurement.

Abstract: Disclosed are a method and apparatus for storing digital content in a storage device. A content key, which is a key used by a host for encrypting content when the content is stored to a storage device connected to the host, is encrypted by using a storage key of the storage device. The encrypted content key and encrypted content are stored in the storage device, and the host only stores storage keys. Thus, quantity of information maintained by the host can be reduced. Also, when a storage key is stored in a portable security component (PSC), portability and mobility of content bound to a single host may be improved.

Abstract: A method of managing and restoring an identifier of a storage device and an apparatus therefor are provided. The method includes the operations of generating a storage device identifier; recording the storage device identifier in a non-volatile memory of a host; generating an identifier file including the storage device identifier and a host identifier; and recording the identifier file in the storage device. By doing so, the method and apparatus can efficiently and securely manage the storage device.

Abstract: A method and apparatus for managing a client revocation list are provided. The method includes receiving a first client revocation list from a server; and selectively discontinuing an operation of a client, based on the first client revocation list. By doing so, the method and the apparatus can securely control contents.

Abstract: Provided is a method of preventing digital content from being used despite the presence of copy control information. In the method, a security apparatus capable of restricting use of contents generates a nonce with respect to a storage device and stores the nonce in the storage device and a memory separated from the storage device when content is stored in the storage device; updates the nonces stored in the memory and storage device when movement of the content occurs; and permits use of the content only when the nonce of the storage device, which is stored in the memory, is equal to the nonce stored in the storage device if the content is requested for use, thereby preventing a disk cloning attack.

Abstract: A method of processing digital content performed by an apparatus for storing digital content. In the method, a hardware regional code extracted from a memory of a content storage device is compared with a firmware regional code extracted from firmware, and the digital content is selectively encrypted and stored according to a corresponding regional code only when the hardware regional code matches the firmware regional code.

Abstract: Provided are a transport stream structure of image data, a transmitting and receiving apparatus and method thereof. A transport stream structure of image data includes a header compressed by a lossless compression algorithm; an additional information field for additional information of image data, the additional information field being generated based on compressing the header by using the lossless compression algorithm; and a payload including the image data. The transport stream structure of the image data, the transmitting and receiving apparatus and method thereof enables inserting the additional information without changing the size of the related art transport stream structure of the image data.

Abstract: Provided is a method of preventing digital content stored in a universal serial bus (USB) mass storage (UMS) device from being distributed without restriction. In the method, registration data is encrypted in order to allow a UMS device to decrypt and use digital content using time information only within a predetermined term of validity. Accordingly, even if encrypted registration data of a UMS device is disclosed, it is possible to make it difficult for unauthorized devices to store the registration data, thereby preventing content of the UMS device from being distributed without restriction.

Abstract: A method and apparatus for protecting digital content stored in a universal serial bus (USB) mass storage (UMS) device from unlimited distribution are provided. According to the method and apparatus, a UMS device generates a random key according to a request from a user and shows the generated random key to the user, and then, by using the random key, registration data is encrypted. Accordingly, only a USB host that registers the UMS device after the user connects the USB host directly to the UMS device, can freely use digital content of the UMS device, and even if encrypted registration data of the UMS is leaked out, unauthorized devices cannot register the UMS device.

Abstract: A method and an apparatus for providing content encrypted in a broadcast encryption scheme to a plurality of devices in a local network are provided. The method includes: storing a minimal number of keys needed by the devices to decode the encrypted content among a plurality of keys that can be used in the predetermined encryption scheme; and transmitting the stored keys to the devices. Accordingly, it is possible for a local server having a small storage capacity to provide the encrypted content to the devices by storing only the minimal number of keys needed by the devices to decode the encrypted content.