Method and apparatus with linearly homomorphic encryption

A linearly homomorphic encryption (LHE) method that provides circuit privacy, the LHE method performed by one or more processors of a first computing device, the LHE method comprising:

• receiving, via a network by the first computing device, a homomorphic ciphertext of input data from a sender comprising a second computing device;
• sampling, by the first computing device, a coefficient of a linear function from a first discrete Gaussian distribution corresponding to a coset of a plaintext modulus;
• sampling, by the first computing device, a first noise from a predefined second discrete Gaussian distribution;
• generating, by the first computing device, based on the sampled coefficient of the linear function and the sampled first noise, a homomorphic ciphertext of an evaluation result on the input data from the linear function;
• and
• transmitting the homomorphic ciphertext from the first computing device via the network to the second computing device.