Data processing method and device based on homomorphic encryption

A method for generating a homomorphic ciphertext by an electronic device, comprising:

• identifying one or more messages;
• encoding each of the one or more messages to generate a first set and a second set each including one or more ciphertexts;
• and
• outputting a third set corresponding to a multi-key by applying a public key based on the first set and the second set,
• wherein generation of the first set and the second set and the outputting the third set operate in a complexity of O(n), and
• wherein n is equal to a number of the one or more messages and a number of the one or more ciphertexts.

A non-transitory computer readable medium storing instructions that, when executed by at least one processor of an electronic device, cause the electronic device to:

• identify one or more messages;
• encode each of the one or more messages to generate a first set and a second set each including one or more ciphertexts;
• and
• output a third set corresponding to a multi-key by applying a public key based on the first set and the second set,
• wherein generation of the first set and the second set and the output of the third set are controlled to operate with a complexity of O(n), and
• wherein n is equal to a number of the one or more messages or a number of the one or more ciphertexts.