CRYPTO LAB INC.

An electronic apparatus is disclosed. The electronic apparatus includes a memory storing instructions, a communication interface, and at least one processor configured to include a processing circuitry, in which the at least one processor is configured to generate a transmission key based on a second modulus of an extended ring that is larger than a first modulus of a subring, and controls the communication interface to transmit the transmission key to a server.

Disclosed is a server device. The device includes: a communication interface configured to communicate with an external device; a memory storing a plurality of reference data; and a processor. Here, the processor is configured to obtain an inner product operation result based on the plurality of reference data and a homomorphic ciphertext if the homomorphic ciphertext generated using a coefficient encoding method is received from the external device through the communication interface, and transmit at least one of private information retrieval (PIR) result data, private membership test (PMT) result data, or private set intersection (PSI) result data, obtained based on the inner product operation result, to the external device through the communication interface.

An electronic apparatus is disclosed. The electronic apparatus includes a communication interface, a memory, and a processor, in which the processor is configured to generate a public key and a secret key for homomorphic encryption, respectively, and store the public key and secret key in the memory, transmit a homomorphic ciphertext obtained by encrypting target information to a server apparatus, transmit a query to the server apparatus, and when an operation result obtained by operating the query with pieces of information within an indexing range identified based on a preset classification criterion among a plurality of pieces of information stored in the server apparatus is transmitted from the server apparatus, decrypt the operation result using the secret key, identify an order of the target information based on the decrypted operation result, and transmit information on the identified order to the server apparatus to acquire an identifier corresponding to the target information.

Disclosed is an electronic device. The electronic device includes: a memory in which an input encrypted message with dimension N is stored; and a processor configured to transform the input encrypted message with dimension N into an encrypted message with dimension N′, perform linear transformation on the encrypted message with dimension N′, and transform the encrypted message corresponding to a result value of the linear transformation into an output encrypted message with dimension N. The N is a value smaller than N′.

An operation device is disclosed. The operation device includes a memory storing at least one instruction, and a processor executing the at least one instruction, wherein the processor is configured to, by executing the at least one instruction, perform decryption for a homomorphic encryption by using information for a secret key, and the secret key is expressed as a polynomial having a plurality of terms, and the information for the secret key includes information on degrees and coefficients of the plurality of respective terms.

An electronic apparatus processing homomorphic encryption includes at least one processor including processing circuitry and memory, and the at least one processor is configured to obtain a first ciphertext by performing homomorphic encryption on plaintext data with a first secret key, obtain, through a first key switching module, a second ciphertext corresponding to a second secret key based on the first ciphertext, transmit the second ciphertext to the second key switching module, obtain, through a second key switching module, a third ciphertext corresponding to a third secret key based on the second ciphertext, transmit the third ciphertext to a decryption module, and obtain, through the decryption module, the plaintext data by decrypting the third ciphertext based on the third secret key.

Disclosed is an electronic apparatus. The electronic apparatus includes memory storing instructions, and at least one processor including processing circuitry, the at least one processor configured to obtain a Cheon-Kim-Kim-Song (CKKS) ciphertext encoding a real-number message in a predetermined discrete value set, perform SlotToCoeff computation of converting the real-number message into a coefficient expression, perform, based on modulus switching computation with respect to the ciphertext converted into a coefficient expression, discretization of approximating the real-number message converted into a coefficient expression to a closest value in the predetermined discrete value set, perform modulus raising computation of raising modulus to an upper level with respect to the discretized ciphertext, perform CoeffToSlot computation of converting the ciphertext of which modulus is raised into a slot-encoded message, and perform, based on EvalMod computation, modular reduction at the same time as rebooting computation ends with respect to the slot-encoded ciphertext.

An electronic apparatus and a controlling method thereof are disclosed. Specifically, the electronic apparatus includes memory storing instructions, and a processor configured to execute the instructions, and the processor is configured to obtain a complex root of unity data by transforming coefficient data included in an encrypted input ciphertext, obtain a plurality of plaintexts that encode the complex root of unity data in slots based on the complex root of unity data, obtain corrected ciphertexts by applying an encrypted mask and a complex conjugation operation to the plurality of plaintexts, obtain a plurality of rotation results of the corrected ciphertexts based on secret indices corresponding to each of a plurality of valid coefficients of a secret key, obtain an intermediate ciphertext based on the plurality of rotation results, and obtain an output ciphertext that is represented as a modulus value greater than a modulus value of an input ciphertext by performing a complex conjugation operation on the intermediate ciphertext and adding the result thereof to the intermediate ciphertext, and that is decodable with a plaintext vector corresponding to a decoding result of the input ciphertext.

Disclosed is a data management method and apparatus. The data management method includes: obtaining a hash value of a key by using a predetermined hash function for each of a plurality of data in which the key matches a data value, sorting the plurality of data in which the key is changed to the hash value of the key based on the obtained hash value, classifying the plurality of sorted data into a plurality of groups according to a predetermined criterion; encoding the plurality of data classified into the plurality of groups, and generating a lookup table based on a predetermined hash value included in each of the plurality of classified groups.

An electronic apparatus which generates a homomorphic encrypted message by homomorphically encrypting voting analysis data includes: a processor configured to execute the at least one instruction, wherein the processor is configured to generate a vote-homomorphic encrypted message including the voting data of the voter for a first candidate and a second candidate by using a first candidate mask corresponding to the first candidate in a first election and a second candidate mask corresponding to the second candidate in a second election, for a first election-homomorphic encrypted message acquired by homomorphically encrypting the voting data of the voter in the first election and a second election-homomorphic encrypted message acquired by homomorphically encrypting the voting data in the second election, and generate a result-homomorphic encrypted message including the number of voters who select the first candidate and the second candidate by using the generated vote-homomorphic encrypted message.