Abstract: A method for performing an operation according to one embodiment includes performing a homomorphic operation using one or more ciphertexts that are homomorphically encrypted based on an encryption key, determining a count value for a ciphertext generated through the homomorphic operation based on count values for each of the one or more ciphertexts, requesting a key management apparatus, which holds the encryption key and a decryption key corresponding to the encryption key, to re-encrypt the generated ciphertext based on the determined count value, acquiring, from the key management apparatus, a ciphertext generated by re-encrypting the generated ciphertext through decryption based on the decryption key and encryption based on the encryption key; and determining a count value for the acquired ciphertext to be a preset initial value.

Abstract: A ciphertext comparison method uses homomorphic encryption. An apparatus performs the ciphertext comparison method using the homomorphic encryption. The ciphertext comparison method using homomorphic encryption includes acquiring a first ciphertext obtained by encrypting first real-number data using a homomorphic evaluation algorithm and a second ciphertext obtained by encrypting second real-number data using the homomorphic evaluation algorithm, and generating a ciphertext for a result for comparison in size between the first real-number data and the second real-number data using homomorphic evaluation for the first ciphertext, the second ciphertext, and an approximation function for approximating a signum function.

Abstract: A method for data analysis according to an embodiment includes acquiring, from a client device, a ciphertext for a precomputation result generated by applying some of a plurality of operations for performing an analysis algorithm based on target data to the target data, and generating an encrypted computation result for remaining operations of the plurality of operations by using the ciphertext.

Abstract: A method for encryption according to an embodiment includes generating a ciphertext for a secret key that is an integer vector by using an integer-based first homomorphic encryption algorithm, generating a key stream that is the integer vector from a nonce and the secret key by using a key stream generator, encoding the key stream by using a message encoding function of the first homomorphic encryption algorithm, encoding a message that is a real vector by using a message encoding function of a real number-based second homomorphic encryption algorithm, generating a ciphertext for the message by using a result of the encoding of the key stream and a result of the encoding of the message, and transmitting the nonce, the ciphertext for the secret key, and the ciphertext for the message to an apparatus for converting a ciphertext.

Abstract: A method for training an analysis model according to an embodiment includes receiving synthetic data for original data from a client apparatus, determining a hyperparameter value for analysis model training using the synthetic data, receiving a ciphertext for the original data from the client apparatus, and training the analysis model using the determined hyperparameter value and the received cipher text.

Abstract: A method for performing an operation according to one embodiment includes performing a homomorphic operation using one or more ciphertexts that are homomorphically encrypted based on an encryption key, determining a count value for a ciphertext generated through the homomorphic operation based on count values for each of the one or more ciphertexts, requesting a key management apparatus, which holds the encryption key and a decryption key corresponding to the encryption key, to re-encrypt the generated ciphertext based on the determined count value, acquiring, from the key management apparatus, a ciphertext generated by re-encrypting the generated ciphertext through decryption based on the decryption key and encryption based on the encryption key; and determining a count value for the acquired ciphertext to be a preset initial value.

Abstract: A method of provisioning key information and a device using the method are provided. The method of provisioning key information according to one embodiment of the present disclosure includes generating key information for encryption and decryption from seed information using a key information generation algorithm and deleting code that corresponds to the key information generation algorithm from the device based on the generation of the key information.

Abstract: An apparatus and method for performing an operation which are secure against side-channel attack are provided. According to one embodiment of the present disclosure, the apparatus includes a first outputter configured to output a first output value corresponding to a seed value using a first parameter candidate value set, a second outputter configured to output a second output value using a second parameter candidate value set wherein the second output value corresponds to the seed value and is capable of being generated using the first output value, a third outputter configured to output a third output value using the seed value and the first output value, and a fourth outputter configured to output a fourth output value using the second output value and the third output value, wherein the fourth output value is capable of being generated using the seed value.

Abstract: A method for performing an operation according to an embodiment includes assigning an error value to encrypted data; and performing a homomorphic operation for an approximation function, which is obtained by approximating a target function, by using, as an input value, the encrypted data to which the error value is assigned.

Abstract: An apparatus for set intersection operation according to an embodiment includes a ciphertext acquisition unit configured to acquire a ciphertext for a first vector corresponding to a first subset of a universal set including a plurality of elements from an encryption apparatus, a transform unit configured to generate a second vector corresponding to a second subset of the universal set, a computation unit configured to generate a ciphertext for a third vector corresponding to an intersection of the first subset and the second subset, based on the ciphertext for the first vector and the second vector, and a ciphertext providing unit configured to provides the ciphertext for the third vector to the encryption apparatus.

Abstract: A system and method for communication between devices are provided. According to the embodiments of the present disclosure, it is possible to easily authenticate a counterpart device using a one-time key HN(T) for a D2D communication between a first device and a second device, without using a separate secure channel (e.g., secure sockets layer (SSL), transport layer security (TLS), or the like) in an environment where it is difficult to synchronize the first device with the second device without intervention of a server.

Abstract: An authentication system and method are provided. According to the embodiments of the present disclosure, it is possible to provide a secure authentication service capable of maintaining personal privacy by enabling authentication while preventing personal information used for personal authentication, such as biometric information, from being exposed in the authentication process.

Abstract: An apparatus and method for performing operation being secure against side channel attack are provided. The apparatus and method generate values equal to values obtained through an exponentiation operation or a scalar multiplication operation of a point using values extracted from previously generated parameter candidate value sets and an operation secure against side-channel attack, thereby improving security against side-channel attack without degrading performance.

Abstract: An apparatus for encryption according to an embodiment of the present disclosure comprises a classifier configured to classify each data included in an original data set into one of encryption target data and non-encryption target data on the basis of at least one of determination on whether or not an operation to be applied to each data included in the original data set for an analysis of the original data set is a preset operation and determination on whether or not each data included in the original data set is sensitive information; and an encryptor configured to encrypt the encryption target data among the data included in the original data set using a homomorphic encryption algorithm.

Abstract: An apparatus and method for performing an operation which are secure against side-channel attack are provided. According to one embodiment of the present disclosure, the apparatus includes a first extractor configured to extract one or more first parameter candidate values corresponding to a seed value from a first parameter candidate value set, a first outputter configured to output a first output values using the extracted first parameter candidate values, a second extractor configured to extract one or more second parameter candidate values corresponding to the seed value from a second parameter candidate value set, and a second outputter configured to output a second output value using the extracted second parameter candidate values wherein the second output value is capable of being generated using the first output value.

Abstract: A refrigerator and a method for controlling the same are disclosed. The refrigerator may minimize the size and material cost of the control system by controlling the internal temperature and the speed of a compressor using a thermostat used in the conventional low-capacity/low-cost refrigerator without using a system controller equipped with various sensors (internal sensors and/or external sensors) capable of controlling the internal temperature. In addition, since an inverter controller capable of controlling a BDLC compressor estimates the internal/external temperature based on operation information of the compressor, and determines the internal load, it may save energy and reduce vibrations and noise, which are the largest disadvantages of a constant-speed compressor, thereby improving satisfaction of the consumer. In addition, the BLDC compressor may be started and operated stably by applying a differentiated algorithm of the inverter controller.

Abstract: A method of generating a secret key according to one embodiment includes generating a share of each of a user and a plurality of other users for a secret key of the user, providing the share of each of the plurality of other users to a user terminal of each of the plurality of other users, receiving a share of the user for a secret key of each of the plurality of other users from the user terminal of each of the plurality of other users, and generating a new secret key of the user using the share of the user for the secret key of the user and the shares of the user for the secret key of each of the plurality of other users.

Abstract: An apparatus for sharing data according to one embodiment includes a first combined data generator configured to generate first combined data by combining target data to be shared and a random bit string, a data encryptor configured to generate a ciphertext for the first combined data, a key encryptor configured to generate one or more ciphertexts for a decryption key of the ciphertext for the first combined data using one or more public keys, a second combined data generator configured to generate second combined data by combining the ciphertext for the first combined data, the one or more ciphertexts for the decryption key, and the random bit string, and a data discloser configured to disclose the second combined data to one or more entities to share the target data to be shared.

Abstract: An apparatus and method for performing operation being secure against side channel attack are provided. The apparatus and method generate values equal to values obtained through an exponentiation operation or a scalar multiplication operation of a point using values extracted from previously generated parameter candidate value sets and an operation secure against side-channel attack, thereby improving security against side-channel attack without degrading performance.

Abstract: Embodiments of the present disclosure relate to refrigerators and methods of controlling the refrigerators. The refrigerator comprises a compressor configured to operate at a first rotation speed and a controller configured to calculate a first average of levels of electric signals input to the compressor during a first reference period, and control the compressor to operate at a second rotation speed higher than the first rotation speed when the first average is greater than a first reference value.