Abstract: A conference session key distribution method used in an ID-based cryptographic system includes selecting two different temporary secret keys, generating a message and generating session key generation variables using the temporary secret keys of a session initiating party. Only valid participating parties receive the session key generation variables. Each party determines the session shared key from the session key generation variables.

Abstract: An elliptic curve cryptography method which generates a public key for use in a communication encryption using an elliptic curve, including: changing a number of a secret key (d) of (k) bits to an odd number; encoding the secret key to yield an encoded secret key (d) in which a most significant bit (MSB) is (1) and a rest positional number is (1) or (?1); and computing the public key (Q=Dp) by multiplying the encoded secret key (d) by a predetermined point (P) on the elliptic curve by a scalar multiplication.

Abstract: A mutual exclusion method and DRM device is provided. The mutual exclusion method includes receiving an instruction associated with a predetermined stored file from the CE device, checking whether a performing instruction being performed associated with the predetermined stored file exists, and generating a collision error message informing that a collision error has occurred due to the inputted instruction when the performing instruction being performed associated with the predetermined stored file exists.

Abstract: A method of providing a content service and an authentication method between devices using broadcast encryption, a display device, and a resource-constrained device are provided. A method of providing a content service, the method including: transmitting, to a display device, an identification (ID) of a resource-constrained device via the resource-constrained device; receiving encryption information from the display device via the resource-constrained device; and decrypting the encryption information by using a stored secret key set via the resource-constrained device.

Abstract: A security system using an RSA algorithm that includes a key input section for receiving a secret key and a public key used in one of encryption and decryption of a message, a random coefficient generating section for generating a random coefficient r having a bit of a predetermined size, a first calculation section for dividing the secret key into a first secret key and a second secret key by using the value of r, and performing an exponentiation of RSA algorithm by using the respective secret keys and the public key, and a second calculation section for performing one of the encryption and the decryption by combining results of exponentiation calculated respectively by using the first and the second secret keys.

Abstract: A method and system for updating time information of a digital rights management (DRM) includes a time server transmitting a time information message to a consumer electronics (CE) device, the CE device transmitting the time information message to a digital rights management DRM device when the CE device receives the time information message from the time server, and the DRM device updating a present time of the DRM device based on the time information message when the DRM device successfully performs authentication with respect to the time information message which has been transmitted from the CE device.

Abstract: A digital rights management (DRM) function performing method and system using a DRM device are provided, in which a DRM device connected to a second communication device decodes encoded contents when a first communication device requests to play the contents, the DRM device re-encodes the contents using a session key, and the DRM device transmits the re-encoded contents to the first communication device via the second communication device.

Abstract: A mutual exclusion method and DRM device is provided. The mutual exclusion method includes receiving an instruction associated with a predetermined stored file from the CE device, checking whether a performing instruction being performed associated with the predetermined stored file exists, and generating a collision error message informing that a collision error has occurred due to the inputted instruction when the performing instruction being performed associated with the predetermined stored file exists.

Abstract: A method and an apparatus are provided for generating an encryption key for broadcast encryption. The method of generating the encryption key for the broadcast encryption includes generating a first encryption key with respect to all nodes, configured in a plurality of depths, from a root node to a plurality of leaf nodes, and generating a second encryption key with respect to each intermediate node between the root node and the plurality of leaf nodes, wherein the generation of the second encryption key comprises generating any one of first and second keys using the first encryption key depending on whether a first child node, connected to a sibling node of the intermediate node, is on a left path or a right path of the intermediate node.

Abstract: A device authentication method using broadcast encryption is provided, in which, a hash value corresponding to a group key version is generated, the generated hash value is encrypted with a group key, group key information comprising the encrypted hash value is generated, and the generated group key information including a signature of an authentication server for the group key information is transmitted. Accordingly, mutual authentication is accomplished by using the group key version including in the group key information.

Abstract: A user key allocation method for broadcast encryption is provided. The user key allocation method includes generating a plurality of subsets by dividing one group including a plurality of nodes to sub-groups and allocating key sets with respect to the subsets, respectively. The nodes included in the subset may be odd nodes and even nodes of the nodes of the group. The nodes are arranged so that privileged nodes are consecutive or there is only one privileged node. Accordingly, it is possible to reduce the data size transmitted from the server to the nodes by constituting one or more subsets from the nodes consecutively arranged and providing key sets with respect to the subsets.

Abstract: An apparatus for providing a rights resale function and a method thereof are provided, in which a rights object to execute content can be freely transferred and shared among users on the intervention of a rights issuer. The apparatus for providing a rights resale function applied to a system which includes a rights acquisition agent and a rights issuer, includes a storage unit for storing a content related rights object, a token generation unit for generating a token for rights resale such as a token for reselling rights to obtain an issuance of the content related rights object from the rights issuer, with reference to the rights object from the storage unit, and a transmission/reception unit for transmitting the token for rights resale from the token generation unit to the rights acquisition agent.

Abstract: A communication apparatus having a public key authentication function and a communication method thereof are disclosed. The communication apparatus includes a calculating unit to calculate a first user authentication data for authenticating public information, and a transmitting and receiving unit to transmit the calculated first user authentication data and the public information to be authenticated, and to transmit a password in a form in which a user characteristic input for authenticating the public information is reflected. Accordingly, if the parties to a communication unexpectedly request mutual authentication under an IP-based communication environment, the apparatus can safely authenticate the public information with a use of a user characteristic sensing channel.

Abstract: An improved security device for digital contents and a method for using the security device are provided. The improved security device and method include a transmission and reception unit for transmitting and receiving data necessary for authentication with a mobile device, and for transmitting and receiving contents of the mobile device and a controller for performing authentication with the mobile device, and for decrypting re-encrypted contents from the mobile device when the authentication is successful. The improved method and device provide enhance mobility for users.

Abstract: A system and method for transmitting and receiving secret information, a device using the same, and a wireless local communication device. The system for transmitting and receiving secret information includes at least one device to generate a ciphertext using public key information that is received over a location-limited channel; and a wireless local communication device to transmit the public key information to the device over the location-limited channel and to decrypt the ciphertext generated at the device. Thus, the secret information can be securely transmitted and received between devices regardless of reliability of the transmission channel.

Abstract: A network capable of communicating with foreign networks and having a plurality of devices capable of mutually communicating with one another and a domain setup method thereof. The network includes at least one main remote controller for, out of the devices, setting up authorization to use the respective devices belonging to at least one main domain having at least one of the devices; and at least one subsidiary remote controller for receiving authentication for authorization to use the respective device belonging to a domain having the respective devices authorized to at least one user by the respective main remote controllers. Thus, the present network enables each user to efficiently administer whether to use the home devices as well as enables the home devices authorized to each user to be set up in one domain in order to keep security and privacy from foreign domains.

Abstract: An ownership sharing method and apparatus using a secret key in a home network remote controller are provided. A user who owns a home device generates an ownership authentication key using the secret key shared with the home device through the user's terminal device, and transmits the ownership authentication key to a terminal device of a particular user who wishes to share the ownership. The particular user can use the home device using the shared ownership authentication key, allowing for ownership of a device in home network environments based on a secret key that can be easily shared, obviating complicated calculation procedures that are no needed to share the ownership between an owner of a device and his family or customers, and achieving high security that is guaranteed based on the secret key.

Abstract: A method is provided for generating a group key, including sharing a plurality of secrete keys with a plurality of nodes adjacent to a first node of the plurality of nodes, obtaining a plurality of function values using the plurality of secrete keys and a result value using the plurality of function values, broadcasting the result value, receiving a plurality of result values generated using a method by which the result value has been obtained, from nodes of the plurality of nodes except for a corresponding node, and obtaining a group key using a plurality of function values extracted from the plurality of function values and the plurality of result values.

Abstract: A communication system including a device, an access point (AP) communicating with the device, and a mobile terminal communicating with the device and the AP, and a method in which the device and the AP share a device key that is a private key used in wireless local area network (WLAN) communication, are provided. A one-directional function operation module is provided in each component constituting the communication system, thereby enabling one-directional function operation. Data to be transmitted and received is applied to one-directional function operation in one-directional function operation module, such that the data can be securely transmitted or received.

Abstract: A method and system for authenticating a home device in a home network, includes generating a home key for authentication of the home device, receiving a secret key corresponding to the home device from the home device, encrypting the home key with the received secret key, and transmitting the encrypted home key to the home device. The home device decodes the encrypted home key using the secret key and then stores the home key. Accordingly, the authentication of the home device is performed without requiring a home server, which would cause an overhead, and the processing of a guest device and a revoked device are performed.