Abstract: A radio frequency identification (RFID) tag encryption method and system using a broadcast encryption (BE) scheme are provided by encrypting an ID of an RFID tag, storing the encrypted ID in a server and the RFID tag, and storing information relating to a reader authorized to read out the RFID tag in the server so that the reader can read out the RFID tag by decrypting the encrypted ID based on the encrypted ID information read from the RFID tag and the reader information. When readers read out ID data from the RFID tag, a privileged reader can read the data. Thus, it is possible to block unintended information leakage to the readers. In addition, user usability can be enhanced since an attacker cannot perform an access lock on the RFID tag.

Abstract: A radio frequency identification (RFID) tag encryption method and system using a broadcast encryption (BE) scheme are provided by encrypting an ID of an RFID tag, storing the encrypted ID in a server and the RFID tag, and storing information relating to a reader authorized to read out the RFID tag in the server so that the reader can read out the RFID tag by decrypting the encrypted ID based on the encrypted ID information read from the RFID tag and the reader information. When readers read out ID data from the RFID tag, a privileged reader can read the data. Thus, it is possible to block unintended information leakage to the readers. In addition, user usability can be enhanced since an attacker cannot perform an access lock on the RFID tag.

Abstract: A signal processing apparatus for performing modular multiplication for use in a signal processing system includes a first logic for outputting a signed multiplicand by selectively performing a one's complementary operation on a multiplicand according to a Booth conversion result of a multiplier in modular multiplication; a second logic for outputting a modulus which is signed in the modular multiplication based on a carry input value Carry-in of a current clock, determined from a carry value cin for correction of a previous clock, and on a sign bit of the multiplicand; and a third logic for receiving the signed multiplicand and the signed modulus, and calculating a result value of the modular multiplication by iteratively performing a full addition operation on a carry value C and a sum value S of the full addition operation, found at the previous clock. The present invention provides a high-speed modular multiplication apparatus with fewer gates and reduced power consumption.

Abstract: A method and apparatus to square an element A when a defining polynomial of a finite field GF(2n) is expressed as f ? ( x ) = x n + ? i = 1 t ? ? x k i + 1 , and the element A contained in the finite field is expressed as A=(a0,a1,a2, . . . ,an?1)?GF(2n).

Abstract: The present invention relates to a system and method for restricting recording of contents using a device key of a content reproduction device. A content recording device includes a content recording unit for encrypting contents using a Content Encryption Key (CEK) and recording the encrypted contents in a recording medium; a CEK transmitting/receiving unit for transmitting the CEK to at least one content reproduction device, and receiving, from the at least one content reproduction device, an encrypted CEK being encrypted using a device key of each of the at least one content reproduction device; and a CEK recording unit for recording the encrypted CEK in the recording medium.

Abstract: A method of obtaining C=(c0, . . . , cn?1) of a product of two elements A and B of a finite field GF(2n). The method includes permuting the last d coefficients (an?1, . . . , an?d) of a multiplier A with predetermined variables (sn?1, . . . , sn?d); operating C:C=?(bi+j?A) for (I+j)th coefficient of a multiplicand B to update coefficients of C, where i and j are integers, and A:=(s, . . . ,?x?2)?(0,xn?1?j?f1, . . . ,sx?1?j?fx?d,0, . . . ,0) repeatedly for j=0 to (d?1) to update coefficients of A, where ? represents an XOR operation and ? represents an AND operation; and repeatedly performing the permuting and operating by increasing i from 0 to (n?1) by d.

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 rekey index generation method and a rekey index generation apparatus are provided. The rekey index generation method includes inserting join information to a first field of a rekey index when new members join a group; and inserting node numbers, corresponding to each of the new members, into a second field of the rekey index for a receiver to select a necessary key from among transmitted encoded keys.

Abstract: A group key update method and a group key update apparatus for updating a key of members in a group are provided. The group key update method includes selecting a sub-root node among nodes on the binary tree; performing a node change with respect to the group according to a type of the sub-root node, and generating a changed binary tree; and performing a node key update with respect to the changed binary tree.

Abstract: A key update method and a key update apparatus are provided. The method includes storing data in a database of an update server, the data having an encoded updated node key in response to a node key update for a group; selecting necessary data, from among the data having the encoded updated node key, to calculate a key immediately prior to when the member is switched to the online mode, and generating member update data; and performing a key update with respect to the member using the member update data in a device corresponding to the member which has switched from the offline mode to the online mode.

Abstract: Provided are a method of generating a node identifier including padding information and location information, in a tree structure, a computer-readable storage medium storing a program for executing a method of generating a node identifier in a tree structure, and a terminal apparatus using the tree structure. The location information is generated by using branch identifiers, each of the branch identifiers being allocated for each branch from a root node to a target node. The padding information is generated by a padding code, which includes information about a group of the target node, and depth information, which includes information about a level of the target node in the tree structure.

Abstract: A method and apparatus for updating a group key of a group corresponding to a binary tree are provided. The method includes updating keys of leaf nodes that correspond to new members, in response to a join of at least two new members joining the group; determining whether both of two child nodes of a single ancestor node are updated when updating a key of the single ancestor node of the leaf nodes; establishing one of the two child nodes as an update use node when both the two child nodes are updated; and updating a key of the ancestor node using the updating node. Thus, the group key may be effectively updated with respect to multi-join.

Abstract: There are provided efficient basis conversion matrices Dsd and Dds and a basis conversion method in a finite field GF(2n) using the basis conversion matrices for a case where a defining polynomial is a pentanomial, xn+xk(3)+xk(2)+xk(1)+1, and the exponents n, k(3), k(2), and (k1) satisfy the condition, n?k(3)>k(3)?k(1). In addition, an apparatus for the basis conversion in the finite field GF(2n) is provided. Since a pentanomial having a general form in an arbitrary degree is used as the defining polynomial, basis conversion between a standard representation and a dual representation is efficiently performed. Consequently, a dual basis multiplier can be efficiently implemented.

Abstract: Provided is an apparatus for encryption/decryption and electronic signature in a mobile communication environment. A signal processing apparatus, performing modular multiplication in an electronic device, includes a first logic for outputting a signed multiplicand by selectively performing a one's complementary operation on a multiplicand according to a Booth conversion result of a multiplier in modular multiplication; a second logic for outputting a modulus which is signed in the modular multiplication based on a carry input value Carry-in of a current clock, determined from a carry value cin for correction of a previous clock, and on a sign bit of the multiplicand; and a third logic for receiving the signed multiplicand and the signed modulus, and calculating a result value of the modular multiplication by iteratively performing a full addition operation on a carry value C and a sum value S of the full addition operation, found at the previous clock.

Abstract: Disclosed are a method and apparatus capable of reducing the number of computations required to generate a digital signature by a digital signature generator. A digital signature generator generates a code word for a received message by a function F for generating a code word having a set weight value and generates a digital signature based on the generated code word and an inverse of a public parity check matrix H, the parity check matrix H is one way function. A digital signature receiver converts the received message using the function F for generating a code word, and multiplies a public parity check matrix H by a received digital signal, the public parity check matrix H is a one way function, and comparing the converted value with the multiplication result.

Abstract: A video fingerprint insertion apparatus is provided. A frequency domain selection unit selects a frequency domain into which a fingerprint is inserted, from frequency domains of a video; a fingerprint insertion position determination unit determines a position where the fingerprint is to be inserted, based on a fingerprint insertion determination value in the selected frequency domain; and a fingerprint insertion unit inserts a fingerprint bit stream whose insertion strength is controlled, to the position where the fingerprint is to be inserted.

Abstract: A method and device for updating a group key are disclosed. The group key updating method comprises determining a start node for a key update on a binary tree, updating a node key of the start node for a key update, updating a node key of a parent node of a node corresponding to the updated node key using the updated node key, and repeatedly performing the updating of the node key of the parent node, and then updating a node key corresponding to a root node of the binary tree. With the disclosed method and device, it is possible to efficiently perform a group key update process.

Abstract: A video watermarking apparatus and method are provided, including an information provider for providing spatial domain segmentation information of an image with respect to a compressed video, a grouping unit for grouping the compressed video, based on the spatial domain segmentation information, and generating a grouped spatial domain, an extraction domain selector for selecting an extraction domain for extracting a watermark from the grouped spatial domain, and a watermark extractor for extracting a watermark bit inserted in the extraction domain.

Abstract: An apparatus and method for video watermarking are provided. The apparatus and method include receiving a bit stream encoded by a video encoder by a spatial domain information analyzer and extracting information from a spatial domain of an image with respect to code words forming the bit stream, grouping the code words for each segmented domain by a domain classifier based on the information from the spatial domain, determining a sign of the each segmented domain by a domain sign determiner and inserting a watermark in the each segmented domain according to the sign determined by the domain sign determiner by a watermark bit inserter.

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.