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 calculation device is disclosed. The calculation device includes: a memory storing at least one instruction and identity information; and a processor performing the at least one instruction, wherein the processor may randomly sample small elements, generate a function-processed output value by function-processing the stored identity information, and generate an encrypted text for a message by using a master public key computed using a ring having a dimension (d) represented by a power of 2 and an integer multiplication of 3 or more, the sampled small elements and the function-processed output value.

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: 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: 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: An electronic device is disclosed.

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: 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 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.