Abstract: A mobile device is disclosed. The device includes a communicator, a GPS unit for calculating location information, a memory, a display, and a processor, and the processor is configured to generate movement path information of the mobile device by performing homomorphic encryption of a plurality of pieces of location information stored in the memory, transmit the movement path information to a server apparatus through the communicator, based on operation result data obtained by operating based on the movement path information and comparison target path information being transmitted from the server apparatus, decrypt the operation result data, and output a message notifying whether a route overlaps the comparison target path information based on a decrypted result through the display. Therefore, the route overlap is rapidly and accurately confirmed without invasion of privacy.

Abstract: Disclosed is a ciphertext calculation method. The ciphertext calculation method comprises the steps of: receiving a comparative calculation command for a plurality of ciphertexts of the same type; performing a calculation by reflecting the plurality of ciphertexts of the same type on a synthesis function corresponding to the comparative calculation command; and outputting the calculated ciphertexts of the same type.

Abstract: A method of operating a homomorphic ciphertext is disclosed. The method of operating a homomorphic ciphertext includes receiving a non-polynomial operation command with respect to a homomorphic ciphertext, computing an approximate polynomial function corresponding to the non-polynomial operation, performing an operation of the homomorphic ciphertext using the computed polynomial function, and outputting the operated homomorphic ciphertext, wherein the approximate polynomial function is a second approximate polynomial function which is obtained by extending a first approximate polynomial function to have a second range wider than the first range having a preset accuracy with the non-polynomial operation within a first range.

Abstract: An electronic device is disclosed. The electronic device comprises: a memory for storing at least one instruction; and a processor for executing at least one instruction, wherein the processor executes the at least one instruction so as to, when an operation command for a homomorphic ciphertext is input, obtain an operation result by using a plaintext operation corresponding to the operation command and a plaintext corresponding to the homomorphic ciphertext, and output the obtained operation result in a manner corresponding to the operation command.

Abstract: Disclosed are a calculation device for encryption using a public key and an encryption method thereof. The present method comprises: a step for setting a secret key, and generating a public key using the secret key and an error extracted from a discrete Gaussian distribution or a distribution that is within a short statistical distance thereto; and a step for applying the public key to a message, and then performing a rounding process to encrypt the message. Accordingly, encryption efficiency can be enhanced.

Abstract: Disclosed is a method of generating digital signature information comprising: receiving a message; computing a particular solution in which a result of calculating the particular solution in a public key becomes a function-processed output value predetermined in the received message; and generating digital signature information for the message using the computed particular solution, wherein the public key is computed using a ring having a dimension (d) represented by a power of 2 and an integer multiplication of 3 or more.

Abstract: Disclosed is a ciphertext computation method. The ciphertext computation method includes: receiving a modular computation command for a plurality of ciphertexts; performing a modular computation for the plurality of ciphertexts by using a lookup table storing a plurality of predetermined prime number information; and outputting a result of the computation.

Abstract: Disclosed is a calculation device. The present calculation device includes: a memory for storing a plurality of homomorphic ciphertexts for an approximate message including an error; and a processor for sorting the plurality of homomorphic ciphertexts by using a 5-way sorter which can sort five homomorphic ciphertexts in a single stage.

Abstract: An encryption method includes: calculating a second random matrix using a first random matrix and a secret key, and generating a ciphertext corresponding to a message using the second random matrix. The generating of the ciphertext includes: performing a rounding process for sending the generated ciphertext to a smaller modulus area. The generating of the ciphertext includes performing message encryption without Gaussian sampling.

Abstract: A data sharing method of a user device is provided. The data sharing method includes receiving, from a server device storing information, a private key corresponding to the information, performing a homomorphic encryption of the private key by a homomorphic encryption key provided from the server device, and generating a switch key, and uploading the switch key to a blockchain system. Accordingly, a more effective and clear data sharing is provided.

Abstract: Disclosed is a method of arithmetic operation. The arithmetic operation includes receiving an input value, generating an output value by reflecting the input value to a preset arithmetic circuit on a finite commutative ring and a first polynomial function to verify the output value, and transferring the generated output value and the first polynomial function to an external device.

Abstract: A method for processing an encryption is provided. The method for processing an encryption includes the steps of linearly transforming a homomorphic encryption for an approximate message including an error, performing an approximate modulus operation for the linearly transformed homomorphic encryption by using a multi-degree polynomial set such that input values within a predetermined range are approximate to an integer point, and linearly transforming the homomorphic encryption which was approximately modulus operated into a form of encryption.

Abstract: An encoding method is disclosed. The present encoding method comprises the steps of: receiving a plurality of messages; encoding the plurality of messages into a polynomial expression having been multivariately defined, and encoding the multivariately defined polynomial expression so as to generate a homomorphic cyphertext.

Abstract: Disclosed is a ciphertext calculation method. The ciphertext calculation method comprises the steps of: receiving a comparative calculation command for a plurality of ciphertexts of the same type; performing a calculation by reflecting the plurality of ciphertexts of the same type on a synthesis function corresponding to the comparative calculation command; and outputting the calculated ciphertexts of the same type.

Abstract: A decryption method includes: receiving a homomorphic ciphertext; and obtaining a result value added an error value at a message from the received homomorphic ciphertext. The error is disposed on the least significant bit (LSB) side in the homogeneous ciphertext, and the message is disposed at a position adjacent to the error.

Abstract: An operation apparatus and method for processing a homomorphic encrypted message are disclosed. The method includes producing an approximate polynomial corresponding to an operation function to be applied to a homomorphic encrypted message and approximately operating the homomorphic encrypted message using the approximate polynomial. Thus, an encrypted message may be efficiently processed.

Abstract: An encryption method of a terminal device includes: setting a scaling factor; and reflecting the scaling factor in a message to be encrypted, and performing encryption using a public key to generate a homomorphic ciphertext. The homomorphic encryption is, based on a decryption being performed, in a form that a result value obtained by adding an error value to a value obtained by reflecting the scaling factor in the message is restored.

Abstract: The computer-implemented method for authenticating secret information according to an aspect of the present disclosure, comprises receiving, by an authentication server, Q{right arrow over (X)} from a terminal for registering secret information; storing, by the authentication server, the received Q{right arrow over (X)}; receiving, by the authentication server, a vector {right arrow over (Z)} from a terminal for requesting authentication of secret information; calculating, by the authentication server, the inner product of Q{right arrow over (X)} and {right arrow over (Z)}; calculating, by the authentication server, ½(n?the inner product); and determining, by the authentication server, that the authentication is successful if ½(n?the inner product) is within a predetermined value and that the authentication fails otherwise.

Abstract: The present disclosure provides a computer-implemented method for processing dynamic data by dynamic data processing device. The device comprises a homomorphic encryption module and a plurality of computing modules running in parallel. The method comprises carrying out, by the homomorphic encryption module, fully homomorphic encryption to dynamic data received from an object which generates the dynamic data; updating, by the computing module which is not in bootstrapping, the encrypted state variable; and carrying out, by the computing module which completes bootstrapping, the first update to the encrypted state variable. The first update to the encrypted state variable after completion of bootstrapping is carried out by x(t+Nboot)?ANbootx(t)+?j=0Nboot?1ANboot?1?jB(r(t+j)?y(t+j)).

Abstract: An encryption method is provided. According to the encryption method, a scaling factor may be reflected in a message and then, a homomorphic ciphertext may be generated using a public key. The generated ciphertext is, when decryption is performed, generated in a form that a result value obtained by adding an error value to a value obtained by reflecting the scaling factor in the message is restored. Accordingly, a homomorphic ciphertext capable of being computed in a ciphertext state can be effectively generated.