Abstract: An apparatus with a homomorphic encryption operation includes: one or more processors configured to: generate a modified vector by preprocessing vector components of an operand ciphertext of a blind rotation operation based on an order of a polynomial of an output ciphertext of the blind rotation operation and a modulus of the operand ciphertext; and generate a homomorphic encryption operation result by performing the blind rotation operation based on a public key for performing the blind rotation operation and the modified vector.

Abstract: An apparatus including a receiver and a processor configured to generate a modulus switch ciphertext by performing modulus switching with respect to data received by the receiver, the modulus switching including mapping a component of an input ciphertext generated from the received data to an odd number, generate a blind rotated ciphertext by performing a blind rotation operation based on the modulus switched ciphertext, and generate encrypted data, as a homomorphic encryption operation result, by performing key switching based on the blind rotated ciphertext.

Abstract: Disclosed are an apparatus and method with homomorphic encryption using automorphism. A computing apparatus includes one or more processors and a memory storing instructions configured to cause the one or more processors to, for a blind rotation key for performing a blind rotation operation and an operand ciphertext of the blind rotation operation: generate a preprocessed ciphertext by performing preprocessing on the operand ciphertext based on automorphism, and generate an operation result of the homomorphic encryption by performing the blind rotation operation for the operand ciphertext on a vector component of the preprocessed ciphertext and a vector component of the blind rotation key.

Abstract: A homomorphic encryption apparatus and method are disclosed. The homomorphic encryption apparatus includes one or more processors, and memory storing instructions configured to, when executed by the one or more processors, cause the one or more processors to receive a blind rotation key for performing a blind rotation operation and receive an operand ciphertext of the blind rotation operation, generate a first ciphertext by performing addition of a polynomial representation based on the blind rotation key and the operand ciphertext, and generate a target ciphertext by performing key switching and accumulative multiplication based on the first ciphertext.

Abstract: An encryption key generating method and apparatus based on homomorphic encryption, and a ciphertext operation method and apparatus using the generated encrypt key are disclosed. The method of generating an encryption key for performing encryption based on homomorphic encryption includes receiving data, generating a first encryption key and a second encryption key used for encrypting the data based on a secret key, and transmitting the first and second encryption keys.