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.

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: An encryption method is disclosed. The encryption method includes calculating a secret key from a ring as a set closed for addition and multiplication defined between elements, generating a plurality of partial secret keys using the calculated secret key and a random matrix, and distributing the plurality of generated partial secret keys.

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: 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 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: 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: 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 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.

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.