Abstract: Disclosed herein are a method that generates an index for an efficient range search in an encrypted DB, and a decryption apparatus and method that are capable of searching for desired data and decrypting search results using the index generation method. The presented index generation method includes preparing a private key and a one-way function, calculating a tag for an input plaintext interval using the private key and the one-way function, and dividing the plaintext interval into a plurality of partial intervals, encrypting information of a partial interval including plaintext using the tag, and then generating an encrypted index.

Abstract: A dynamic multi-dimensional code generation and recognition apparatus in which time information and visual recognition information are combined, and a method thereof are provided. According to the present invention, a dynamic multi-dimensional code or a time-variant code including visual recognition information which is associated with source information and changed over time is provided. Accordingly, users may easily ascertain existence of the multi-dimensional code and intended contents of the source information.

Abstract: The present invention relates to a compressed encryption and decryption apparatus comprising: an interface receiving a public key, a secret key and a compression ratio; a memory storing instructions for encryption and decryption of plaintexts; and a processor encrypting and decrypting plaintexts according to the instruction, wherein the instruction comprises instructions performing; generating an extended public key and an extended secret key by revising the public key and the secret key according to the compression ratio; outputting the extended public key; receiving compressed ciphertext; and decrypting the compressed ciphertext using modulo operation for multiplication of the extended secret key and the compressed ciphertext.

Abstract: A lightweight group signature system and method with short signatures according to the exemplary embodiments of the present invention can provide security characteristics similar to group signature mechanisms providing the existing known controllable linkability but can make a revocation method simple by outputting a short signature and providing excellent operation efficiency at the time of signature generation, signature verification, and revocation on smart terminals, and can be widely applied to various anonymity-based application environments, making by making operation efficiency excellent at the time of signature generation and verification and outputting very short signature lengths.

Abstract: A multi-user searchable encryption system includes a key generation center to issue a private secret key to a user and trace information regarding a user who has generated an index, and a user terminal device to generate an index for searching for a database using the private secret key. The multi-user searchable encryption system includes a database (DB) server that verifies the index generated by the user terminal device and searches for corresponding data to the verified index.

Abstract: The present invention relates to a technique which provides a function of compressed encryption large pieces of plaintext information in a single ciphertext in order to improve a space efficiency of the encryption data which occupies most of a storage space to design an efficient SHE technique which is a base of the FHE technique design. More specifically, the present invention relates to a technique which is designed to improve a structure in which only one bit is encrypted/decrypted in the technique of the prior art to encrypt/decrypt multiple bit information to improve the space efficiency for storing a ciphertext.

Abstract: Disclosed herein are an apparatus for generating the privacy-protecting document authentication information and a method of performing privacy-protecting document authentication. The apparatus for generating the privacy-protecting document authentication information includes an electronic signature information generation unit, a multi-dimensional code generation unit, and a multi-dimensional code output unit. The electronic signature information generation unit generates electronic signature information for the content of an input document. The multi-dimensional code generation unit generates a multi-dimensional code corresponding to the generated electronic signature information. The multi-dimensional code output unit outputs the generated multi-dimensional code onto the document.

Abstract: An order-preserving encryption apparatus includes an initializer for setting a total space of a ciphertext with respect to a total space of a plaintext by considering security of the ciphertext, and setting a secret key for encryption and a pseudo-random number generator for generation of a pivot. Further, the order-preserving encryption apparatus includes a pivot generator for applying the secret key to the established pseudo-random number generator to generate a pivot for the plaintext to be encrypted. Further, the order-preserving encryption apparatus includes a ciphertext generator for generating information about size of a bit constituting the ciphertext by comparing the generated pivot and the plaintext; and a plaintext adjusting unit for adjusting a magnitude of the total plaintext space and a magnitude of the plaintext according to the ciphertext.

Abstract: Disclosed is a method for searchable symmetric encryption. The method for performing searchable encryption and searching for encrypted data includes: setting all necessary variables and preparing a secret key necessary for encryption; encrypting a data using the secret key and a given data and generating an index to be used for later search, to store the encrypted data and the index; generating a trapdoor to be used to search the encrypted data by using the secret key and a keyword to be used for the searching; and searching a desired data using the generated trapdoor and the stored index.

Abstract: There are provided an apparatus and a method for privacy protection in association rule mining among data mining technologies. An apparatus for privacy protection in association rule mining according to an embodiment of the present invention comprises: a fake transaction inserter that generates fake transactions of a predetermined number each having a predetermined length and inserts the fake transactions between a plurality of transactions comprised in an original data set to generate a first virtual data set; and a distortion transaction generator that generates a second virtual data set by converting data of the transaction of the first virtual data set with a predetermined probability.

Abstract: A method of user-authenticated quantum key distribution according to the present invention shares a position having the same basis without making public basis information using previously shared secret keys and authenticates a quantum channel by confirming whether there is the same measured outcome at that position, in order to secure unconditional security of BB84 quantum key distribution (QKD) protocols vulnerable to man-in-the-middle attack.

Abstract: A lightweight group signature system and method with short signatures according to the exemplary embodiments of the present invention can provide security characteristics similar to group signature mechanisms providing the existing known controllable linkability but can make a revocation method simple by outputting a short signature and providing excellent operation efficiency at the time of signature generation, signature verification, and revocation on smart terminals, and can be widely applied to various anonymity-based application environments, making by making operation efficiency excellent at the time of signature generation and verification and outputting very short signature lengths.

Abstract: A mobility technology for strengthening safety for an invasion of privacy caused by leakage of contact information is provided. A privacy protection system may include an acquisition attempt detecting unit to detect an external communication terminal that attempts to acquire contact information included in the profile, and an access controller to provide the detected external communication terminal with a right to use the contact information, and to determine whether the contact information is to be provided.

Abstract: A dynamic multi-dimensional code generation and recognition apparatus in which time information and visual recognition information are combined, and a method thereof are provided. According to the present invention, a dynamic multi-dimensional code or a time-variant code including visual recognition information which is associated with source information and changed over time is provided. Accordingly, users may easily ascertain existence of the multi-dimensional code and intended contents of the source information.

Abstract: An order-preserving encryption apparatus includes an initializer for setting a total space of a ciphertext with respect to a total space of a plaintext by considering security of the ciphertext, and setting a secret key for encryption and a pseudo-random number generator for generation of a pivot. Further, the order-preserving encryption apparatus includes a pivot generator for applying the secret key to the established pseudo-random number generator to generate a pivot for the plaintext to be encrypted. Further, the order-preserving encryption apparatus includes a ciphertext generator for generating information about size of a bit constituting the ciphertext by comparing the generated pivot and the plaintext; and a plaintext adjusting unit for adjusting a magnitude of the total plaintext space and a magnitude of the plaintext according to the ciphertext.

Abstract: A data management apparatus includes an index generation unit configured to subdivide an entire interval of data into bucket intervals, allocate indices for the respective bucket intervals, transform the bucket intervals having the allocated indices into bucket intervals of specific lengths, and generate bucket-based indices for pieces of data included in the bucket intervals of the specific lengths. The data management apparatus further includes a data management unit configured to transmit the encrypted data and the bucket-based indices to a server-side data management apparatus in order to store the encrypted data, transmit a user query to the server-side data management apparatus in order to search for a desired encrypted data, and decrypt encrypted data corresponding to the user query from the server-side data management apparatus. The user query includes the index of first bucket interval and the index of second bucket interval neighboring to the first bucket interval.

Abstract: Disclosed is a method for searchable symmetric encryption. The method for performing searchable encryption and searching for encrypted data includes: setting all necessary variables and preparing a secret key necessary for encryption; encrypting a data using the secret key and a given data and generating an index to be used for later search, to store the encrypted data and the index; generating a trapdoor to be used to search the encrypted data by using the secret key and a keyword to be used for the searching; and searching a desired data using the generated trapdoor and the stored index.

Abstract: There are provided an apparatus and a method for privacy protection in association rule mining among data mining technologies. An apparatus for privacy protection in association rule mining according to an embodiment of the present invention comprises: a fake transaction inserter that generates fake transactions of a predetermined number each having a predetermined length and inserts the fake transactions between a plurality of transactions comprised in an original data set to generate a first virtual data set; and a distortion transaction generator that generates a second virtual data set by converting data of the transaction of the first virtual data set with a predetermined probability.

Abstract: A user key management method for a broadcast encryption includes assigning node path identifiers (IDs) to nodes arranged in sequence; assigning random seed value keys to the nodes according to the node path IDs; generating key values by repeatedly applying a hash function to the assigned random seed value keys; and assigning the generated key values to the nodes in sequence. Accordingly, it is possible to reduce the transmission overhead that is most important matter in the broadcast encryption to less than the number of the revoked users. Further, there is an advantage that the transmission overhead of the exemplary embodiments of the present invention is remarkably reduced compared with the Subset Difference method.

Abstract: A user key management method for a broadcast encryption includes assigning node path identifiers (IDs) to nodes arranged in sequence; assigning random seed value keys to the nodes according to the node path IDs; generating key values by repeatedly applying a hash function to the assigned random seed value keys; and assigning the generated key values to the nodes in sequence. Accordingly, it is possible to reduce the transmission overhead that is most important matter in the broadcast encryption to less than the number of the revoked users. Further, there is an advantage that the transmission overhead of the exemplary embodiments of the present invention is remarkably reduced compared with the Subset Difference method.